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<!DOCTYPE html>
<html>
<head>
<title>user-microposts</title>
<link rel="stylesheet" href="pygments.css" type="text/css" />
<link rel="stylesheet" href="polytexnic.css" type="text/css" />
</head>
<body>
<div id="book">
<h1 class="title">Ruby on Rails Tutorial </h1>
<h1 class="subtitle"> Learn Web Development with Rails</h1>
<h2 class="author">Michael Hartl</h2>
<h2 class="contents">Contents</h2>
<div id="table_of_contents"><ol><li class="chapter"><a href="beginning.html#top"><span class="number">Chapter 1</span> From zero to deploy</a></li><li><ol><li class="section"><a href="beginning.html#sec-introduction"><span class="number">1.1</span> Introduction</a></li><li><ol><li class="subsection"><a href="beginning.html#sec-comments_for_various_readers"><span class="number">1.1.1</span> Comments for various readers</a></li><li class="subsection"><a href="beginning.html#sec-1_1_2"><span class="number">1.1.2</span> “Scaling” Rails</a></li><li class="subsection"><a href="beginning.html#sec-conventions"><span class="number">1.1.3</span> Conventions in this book</a></li></ol></li><li class="section"><a href="beginning.html#sec-up_and_running"><span class="number">1.2</span> Up and running</a></li><li><ol><li class="subsection"><a href="beginning.html#sec-development_tools"><span class="number">1.2.1</span> Development environments</a></li><li><ol><li class="subsubsection"><a href="beginning.html#sec-1_2_1_1">IDEs</a></li><li class="subsubsection"><a href="beginning.html#sec-1_2_1_2">Text editors and command lines</a></li><li class="subsubsection"><a href="beginning.html#sec-1_2_1_3">Browsers</a></li><li class="subsubsection"><a href="beginning.html#sec-1_2_1_4">A note about tools</a></li></ol></li><li class="subsection"><a href="beginning.html#sec-rubygems"><span class="number">1.2.2</span> Ruby, RubyGems, Rails, and Git</a></li><li><ol><li class="subsubsection"><a href="beginning.html#sec-rails_installer_windows">Rails Installer (Windows)</a></li><li class="subsubsection"><a href="beginning.html#sec-install_git">Install Git</a></li><li class="subsubsection"><a href="beginning.html#sec-install_ruby">Install Ruby</a></li><li class="subsubsection"><a href="beginning.html#sec-install_rubygems">Install RubyGems</a></li><li class="subsubsection"><a href="beginning.html#sec-install_rails">Install Rails</a></li></ol></li><li class="subsection"><a href="beginning.html#sec-the_first_application"><span class="number">1.2.3</span> The first application</a></li><li class="subsection"><a href="beginning.html#sec-bundler"><span class="number">1.2.4</span> Bundler</a></li><li class="subsection"><a href="beginning.html#sec-rails_server"><span class="number">1.2.5</span> <tt>rails server</tt></a></li><li class="subsection"><a href="beginning.html#sec-mvc"><span class="number">1.2.6</span> Model-view-controller (MVC)</a></li></ol></li><li class="section"><a href="beginning.html#sec-version_control"><span class="number">1.3</span> Version control with Git</a></li><li><ol><li class="subsection"><a href="beginning.html#sec-git_setup"><span class="number">1.3.1</span> Installation and setup</a></li><li><ol><li class="subsubsection"><a href="beginning.html#sec-1_3_1_1">First-time system setup</a></li><li class="subsubsection"><a href="beginning.html#sec-1_3_1_2">First-time repository setup</a></li></ol></li><li class="subsection"><a href="beginning.html#sec-adding_and_committing"><span class="number">1.3.2</span> Adding and committing</a></li><li class="subsection"><a href="beginning.html#sec-1_3_3"><span class="number">1.3.3</span> What good does Git do you?</a></li><li class="subsection"><a href="beginning.html#sec-github"><span class="number">1.3.4</span> GitHub</a></li><li class="subsection"><a href="beginning.html#sec-git_commands"><span class="number">1.3.5</span> Branch, edit, commit, merge</a></li><li><ol><li class="subsubsection"><a href="beginning.html#sec-git_branch">Branch</a></li><li class="subsubsection"><a href="beginning.html#sec-git_edit">Edit</a></li><li class="subsubsection"><a href="beginning.html#sec-git_commit">Commit</a></li><li class="subsubsection"><a href="beginning.html#sec-git_merge">Merge</a></li><li class="subsubsection"><a href="beginning.html#sec-git_push">Push</a></li></ol></li></ol></li><li class="section"><a href="beginning.html#sec-deploying"><span class="number">1.4</span> Deploying</a></li><li><ol><li class="subsection"><a href="beginning.html#sec-heroku_setup"><span class="number">1.4.1</span> Heroku setup</a></li><li class="subsection"><a href="beginning.html#sec-heroku_step_one"><span class="number">1.4.2</span> Heroku deployment, step one</a></li><li class="subsection"><a href="beginning.html#sec-1_4_3"><span class="number">1.4.3</span> Heroku deployment, step two</a></li><li class="subsection"><a href="beginning.html#sec-heroku_commands"><span class="number">1.4.4</span> Heroku commands</a></li></ol></li><li class="section"><a href="beginning.html#sec-beginning_conclusion"><span class="number">1.5</span> Conclusion</a></li></ol></li><li class="chapter"><a href="a-demo-app.html#top"><span class="number">Chapter 2</span> A demo app</a></li><li><ol><li class="section"><a href="a-demo-app.html#sec-planning_the_application"><span class="number">2.1</span> Planning the application</a></li><li><ol><li class="subsection"><a href="a-demo-app.html#sec-modeling_demo_users"><span class="number">2.1.1</span> Modeling demo users</a></li><li class="subsection"><a href="a-demo-app.html#sec-modeling_demo_microposts"><span class="number">2.1.2</span> Modeling demo microposts</a></li></ol></li><li class="section"><a href="a-demo-app.html#sec-demo_users_resource"><span class="number">2.2</span> The Users resource</a></li><li><ol><li class="subsection"><a href="a-demo-app.html#sec-a_user_tour"><span class="number">2.2.1</span> A user tour</a></li><li class="subsection"><a href="a-demo-app.html#sec-mvc_in_action"><span class="number">2.2.2</span> MVC in action</a></li><li class="subsection"><a href="a-demo-app.html#sec-weaknesses_of_this_users_resource"><span class="number">2.2.3</span> Weaknesses of this Users resource</a></li></ol></li><li class="section"><a href="a-demo-app.html#sec-microposts_resource"><span class="number">2.3</span> The Microposts resource</a></li><li><ol><li class="subsection"><a href="a-demo-app.html#sec-a_micropost_microtour"><span class="number">2.3.1</span> A micropost microtour</a></li><li class="subsection"><a href="a-demo-app.html#sec-putting_the_micro_in_microposts"><span class="number">2.3.2</span> Putting the <em>micro</em> in microposts</a></li><li class="subsection"><a href="a-demo-app.html#sec-demo_user_has_many_microposts"><span class="number">2.3.3</span> A user <tt>has_many</tt> microposts</a></li><li class="subsection"><a href="a-demo-app.html#sec-inheritance_hierarchies"><span class="number">2.3.4</span> Inheritance hierarchies</a></li><li class="subsection"><a href="a-demo-app.html#sec-deploying_the_demo_app"><span class="number">2.3.5</span> Deploying the demo app</a></li></ol></li><li class="section"><a href="a-demo-app.html#sec-2_4"><span class="number">2.4</span> Conclusion</a></li></ol></li><li class="chapter"><a href="static-pages.html#top"><span class="number">Chapter 3</span> Mostly static pages</a></li><li><ol><li class="section"><a href="static-pages.html#sec-static_pages"><span class="number">3.1</span> Static pages</a></li><li class="section"><a href="static-pages.html#sec-first_tests"><span class="number">3.2</span> Our first tests</a></li><li><ol><li class="subsection"><a href="static-pages.html#sec-TDD"><span class="number">3.2.1</span> Test-driven development</a></li><li class="subsection"><a href="static-pages.html#sec-adding_a_page"><span class="number">3.2.2</span> Adding a page</a></li><li><ol><li class="subsubsection"><a href="static-pages.html#sec-red">Red</a></li><li class="subsubsection"><a href="static-pages.html#sec-green">Green</a></li><li class="subsubsection"><a href="static-pages.html#sec-refactor">Refactor</a></li></ol></li></ol></li><li class="section"><a href="static-pages.html#sec-slightly_dynamic_pages"><span class="number">3.3</span> Slightly dynamic pages</a></li><li><ol><li class="subsection"><a href="static-pages.html#sec-testing_a_title_change"><span class="number">3.3.1</span> Testing a title change</a></li><li class="subsection"><a href="static-pages.html#sec-passing_title_tests"><span class="number">3.3.2</span> Passing title tests</a></li><li class="subsection"><a href="static-pages.html#sec-embedded_ruby"><span class="number">3.3.3</span> Embedded Ruby</a></li><li class="subsection"><a href="static-pages.html#sec-layouts"><span class="number">3.3.4</span> Eliminating duplication with layouts</a></li></ol></li><li class="section"><a href="static-pages.html#sec-static_pages_conclusion"><span class="number">3.4</span> Conclusion</a></li><li class="section"><a href="static-pages.html#sec-static_pages_exercises"><span class="number">3.5</span> Exercises</a></li><li class="section"><a href="static-pages.html#sec-advanced_setup"><span class="number">3.6</span> Advanced setup</a></li><li><ol><li class="subsection"><a href="static-pages.html#sec-eliminating_bundle_exec"><span class="number">3.6.1</span> Eliminating <tt>bundle exec</tt></a></li><li><ol><li class="subsubsection"><a href="static-pages.html#sec-rvm_bundler_integration">RVM Bundler integration</a></li><li class="subsubsection"><a href="static-pages.html#sec-binstubs">binstubs</a></li></ol></li><li class="subsection"><a href="static-pages.html#sec-guard"><span class="number">3.6.2</span> Automated tests with Guard</a></li><li class="subsection"><a href="static-pages.html#sec-spork"><span class="number">3.6.3</span> Speeding up tests with Spork</a></li><li><ol><li class="subsubsection"><a href="static-pages.html#sec-spork_and_guard">Guard with Spork</a></li></ol></li><li class="subsection"><a href="static-pages.html#sec-tests_inside_sublime_text"><span class="number">3.6.4</span> Tests inside Sublime Text</a></li></ol></li></ol></li><li class="chapter"><a href="rails-flavored-ruby.html#top"><span class="number">Chapter 4</span> Rails-flavored Ruby</a></li><li><ol><li class="section"><a href="rails-flavored-ruby.html#sec-motivation"><span class="number">4.1</span> Motivation</a></li><li class="section"><a href="rails-flavored-ruby.html#sec-strings_and_methods"><span class="number">4.2</span> Strings and methods</a></li><li><ol><li class="subsection"><a href="rails-flavored-ruby.html#sec-comments"><span class="number">4.2.1</span> Comments</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-strings"><span class="number">4.2.2</span> Strings</a></li><li><ol><li class="subsubsection"><a href="rails-flavored-ruby.html#sec-printing">Printing</a></li><li class="subsubsection"><a href="rails-flavored-ruby.html#sec-single_quoted_strings">Single-quoted strings</a></li></ol></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-objects_and_message_passing"><span class="number">4.2.3</span> Objects and message passing</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-method_definitions"><span class="number">4.2.4</span> Method definitions</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-back_to_the_title_helper"><span class="number">4.2.5</span> Back to the title helper</a></li></ol></li><li class="section"><a href="rails-flavored-ruby.html#sec-other_data_structures"><span class="number">4.3</span> Other data structures</a></li><li><ol><li class="subsection"><a href="rails-flavored-ruby.html#sec-arrays_and_ranges"><span class="number">4.3.1</span> Arrays and ranges</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-blocks"><span class="number">4.3.2</span> Blocks</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-hashes_and_symbols"><span class="number">4.3.3</span> Hashes and symbols</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-css_revisited"><span class="number">4.3.4</span> CSS revisited</a></li></ol></li><li class="section"><a href="rails-flavored-ruby.html#sec-ruby_classes"><span class="number">4.4</span> Ruby classes</a></li><li><ol><li class="subsection"><a href="rails-flavored-ruby.html#sec-constructors"><span class="number">4.4.1</span> Constructors</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-a_class_of_our_own"><span class="number">4.4.2</span> Class inheritance</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-modifying_built_in_classes"><span class="number">4.4.3</span> Modifying built-in classes</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-a_controller_class"><span class="number">4.4.4</span> A controller class</a></li><li class="subsection"><a href="rails-flavored-ruby.html#sec-a_user_class"><span class="number">4.4.5</span> A user class</a></li></ol></li><li class="section"><a href="rails-flavored-ruby.html#sec-conclusion"><span class="number">4.5</span> Conclusion</a></li><li class="section"><a href="rails-flavored-ruby.html#sec-exercises"><span class="number">4.6</span> Exercises</a></li></ol></li><li class="chapter"><a href="filling-in-the-layout.html#top"><span class="number">Chapter 5</span> Filling in the layout</a></li><li><ol><li class="section"><a href="filling-in-the-layout.html#sec-structure"><span class="number">5.1</span> Adding some structure</a></li><li><ol><li class="subsection"><a href="filling-in-the-layout.html#sec-adding_to_the_layout"><span class="number">5.1.1</span> Site navigation</a></li><li class="subsection"><a href="filling-in-the-layout.html#sec-custom_css"><span class="number">5.1.2</span> Bootstrap and custom CSS</a></li><li class="subsection"><a href="filling-in-the-layout.html#sec-partials"><span class="number">5.1.3</span> Partials</a></li></ol></li><li class="section"><a href="filling-in-the-layout.html#sec-sass_and_the_asset_pipeline"><span class="number">5.2</span> Sass and the asset pipeline</a></li><li><ol><li class="subsection"><a href="filling-in-the-layout.html#sec-the_asset_pipeline"><span class="number">5.2.1</span> The asset pipeline</a></li><li><ol><li class="subsubsection"><a href="filling-in-the-layout.html#sec-5_2_1_1">Asset directories</a></li><li class="subsubsection"><a href="filling-in-the-layout.html#sec-5_2_1_2">Manifest files</a></li><li class="subsubsection"><a href="filling-in-the-layout.html#sec-5_2_1_3">Preprocessor engines</a></li><li class="subsubsection"><a href="filling-in-the-layout.html#sec-5_2_1_4">Efficiency in production</a></li></ol></li><li class="subsection"><a href="filling-in-the-layout.html#sec-sass"><span class="number">5.2.2</span> Syntactically awesome stylesheets</a></li><li><ol><li class="subsubsection"><a href="filling-in-the-layout.html#sec-5_2_2_1">Nesting</a></li><li class="subsubsection"><a href="filling-in-the-layout.html#sec-5_2_2_2">Variables</a></li></ol></li></ol></li><li class="section"><a href="filling-in-the-layout.html#sec-layout_links"><span class="number">5.3</span> Layout links</a></li><li><ol><li class="subsection"><a href="filling-in-the-layout.html#sec-route_tests"><span class="number">5.3.1</span> Route tests</a></li><li class="subsection"><a href="filling-in-the-layout.html#sec-rails_routes"><span class="number">5.3.2</span> Rails routes</a></li><li class="subsection"><a href="filling-in-the-layout.html#sec-named_routes"><span class="number">5.3.3</span> Named routes</a></li><li class="subsection"><a href="filling-in-the-layout.html#sec-pretty_rspec"><span class="number">5.3.4</span> Pretty RSpec</a></li></ol></li><li class="section"><a href="filling-in-the-layout.html#sec-user_signup"><span class="number">5.4</span> User signup: A first step</a></li><li><ol><li class="subsection"><a href="filling-in-the-layout.html#sec-users_controller"><span class="number">5.4.1</span> Users controller</a></li><li class="subsection"><a href="filling-in-the-layout.html#sec-signup_url"><span class="number">5.4.2</span> Signup URL</a></li></ol></li><li class="section"><a href="filling-in-the-layout.html#sec-layout_conclusion"><span class="number">5.5</span> Conclusion</a></li><li class="section"><a href="filling-in-the-layout.html#sec-layout_exercises"><span class="number">5.6</span> Exercises</a></li></ol></li><li class="chapter"><a href="modeling-users.html#top"><span class="number">Chapter 6</span> Modeling users</a></li><li><ol><li class="section"><a href="modeling-users.html#sec-user_model"><span class="number">6.1</span> User model</a></li><li><ol><li class="subsection"><a href="modeling-users.html#sec-database_migrations"><span class="number">6.1.1</span> Database migrations</a></li><li class="subsection"><a href="modeling-users.html#sec-the_model_file"><span class="number">6.1.2</span> The model file</a></li><li class="subsection"><a href="modeling-users.html#sec-creating_user_objects"><span class="number">6.1.3</span> Creating user objects</a></li><li class="subsection"><a href="modeling-users.html#sec-finding_user_objects"><span class="number">6.1.4</span> Finding user objects</a></li><li class="subsection"><a href="modeling-users.html#sec-updating_user_objects"><span class="number">6.1.5</span> Updating user objects</a></li></ol></li><li class="section"><a href="modeling-users.html#sec-user_validations"><span class="number">6.2</span> User validations</a></li><li><ol><li class="subsection"><a href="modeling-users.html#sec-initial_user_tests"><span class="number">6.2.1</span> Initial user tests</a></li><li class="subsection"><a href="modeling-users.html#sec-presence_validation"><span class="number">6.2.2</span> Validating presence</a></li><li class="subsection"><a href="modeling-users.html#sec-length_validation"><span class="number">6.2.3</span> Length validation</a></li><li class="subsection"><a href="modeling-users.html#sec-format_validation"><span class="number">6.2.4</span> Format validation</a></li><li class="subsection"><a href="modeling-users.html#sec-uniqueness_validation"><span class="number">6.2.5</span> Uniqueness validation</a></li><li><ol><li class="subsubsection"><a href="modeling-users.html#sec-the_caveat">The uniqueness caveat</a></li></ol></li></ol></li><li class="section"><a href="modeling-users.html#sec-adding_a_secure_password"><span class="number">6.3</span> Adding a secure password</a></li><li><ol><li class="subsection"><a href="modeling-users.html#sec-a_hashed_password"><span class="number">6.3.1</span> A hashed password</a></li><li class="subsection"><a href="modeling-users.html#sec-password_and_confirmation"><span class="number">6.3.2</span> Password and confirmation</a></li><li class="subsection"><a href="modeling-users.html#sec-user_authentication"><span class="number">6.3.3</span> User authentication</a></li><li class="subsection"><a href="modeling-users.html#sec-has_secure_password"><span class="number">6.3.4</span> User has secure password</a></li><li class="subsection"><a href="modeling-users.html#sec-creating_a_user"><span class="number">6.3.5</span> Creating a user</a></li></ol></li><li class="section"><a href="modeling-users.html#sec-6_4"><span class="number">6.4</span> Conclusion</a></li><li class="section"><a href="modeling-users.html#sec-modeling_users_exercises"><span class="number">6.5</span> Exercises</a></li></ol></li><li class="chapter"><a href="sign-up.html#top"><span class="number">Chapter 7</span> Sign up</a></li><li><ol><li class="section"><a href="sign-up.html#sec-showing_users"><span class="number">7.1</span> Showing users</a></li><li><ol><li class="subsection"><a href="sign-up.html#sec-rails_environments"><span class="number">7.1.1</span> Debug and Rails environments</a></li><li class="subsection"><a href="sign-up.html#sec-a_users_resource"><span class="number">7.1.2</span> A Users resource</a></li><li class="subsection"><a href="sign-up.html#sec-tests_with_factories"><span class="number">7.1.3</span> Testing the user show page (with factories)</a></li><li class="subsection"><a href="sign-up.html#sec-a_gravatar_image"><span class="number">7.1.4</span> A Gravatar image and a sidebar</a></li></ol></li><li class="section"><a href="sign-up.html#sec-signup_form"><span class="number">7.2</span> Signup form</a></li><li><ol><li class="subsection"><a href="sign-up.html#sec-tests_for_user_signup"><span class="number">7.2.1</span> Tests for user signup</a></li><li class="subsection"><a href="sign-up.html#sec-using_form_for"><span class="number">7.2.2</span> Using <tt>form_for</tt></a></li><li class="subsection"><a href="sign-up.html#sec-the_form_html"><span class="number">7.2.3</span> The form HTML</a></li></ol></li><li class="section"><a href="sign-up.html#sec-signup_failure"><span class="number">7.3</span> Signup failure</a></li><li><ol><li class="subsection"><a href="sign-up.html#sec-a_working_form"><span class="number">7.3.1</span> A working form</a></li><li class="subsection"><a href="sign-up.html#sec-strong_parameters"><span class="number">7.3.2</span> Strong parameters</a></li><li class="subsection"><a href="sign-up.html#sec-signup_error_messages"><span class="number">7.3.3</span> Signup error messages</a></li></ol></li><li class="section"><a href="sign-up.html#sec-signup_success"><span class="number">7.4</span> Signup success</a></li><li><ol><li class="subsection"><a href="sign-up.html#sec-the_finished_signup_form"><span class="number">7.4.1</span> The finished signup form</a></li><li class="subsection"><a href="sign-up.html#sec-the_flash"><span class="number">7.4.2</span> The flash</a></li><li class="subsection"><a href="sign-up.html#sec-the_first_signup"><span class="number">7.4.3</span> The first signup</a></li><li class="subsection"><a href="sign-up.html#sec-deploying_to_production_with_ssl"><span class="number">7.4.4</span> Deploying to production with SSL</a></li></ol></li><li class="section"><a href="sign-up.html#sec-7_5"><span class="number">7.5</span> Conclusion</a></li><li class="section"><a href="sign-up.html#sec-signup_exercises"><span class="number">7.6</span> Exercises</a></li></ol></li><li class="chapter"><a href="sign-in-sign-out.html#top"><span class="number">Chapter 8</span> Sign in, sign out</a></li><li><ol><li class="section"><a href="sign-in-sign-out.html#sec-signin_failure"><span class="number">8.1</span> Sessions and signin failure</a></li><li><ol><li class="subsection"><a href="sign-in-sign-out.html#sec-sessions_controller"><span class="number">8.1.1</span> Sessions controller</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-signin_tests"><span class="number">8.1.2</span> Signin tests</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-signin_form"><span class="number">8.1.3</span> Signin form</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-reviewing_form_submission"><span class="number">8.1.4</span> Reviewing form submission</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-rendering_with_a_flash_message"><span class="number">8.1.5</span> Rendering with a flash message</a></li></ol></li><li class="section"><a href="sign-in-sign-out.html#sec-signin_success"><span class="number">8.2</span> Signin success</a></li><li><ol><li class="subsection"><a href="sign-in-sign-out.html#sec-remember_me"><span class="number">8.2.1</span> Remember me</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-a_working_sign_in_method"><span class="number">8.2.2</span> A working <tt>sign_in</tt> method</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-current_user"><span class="number">8.2.3</span> Current user</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-changing_the_layout_links"><span class="number">8.2.4</span> Changing the layout links</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-signin_upon_signup"><span class="number">8.2.5</span> Signin upon signup</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-signing_out"><span class="number">8.2.6</span> Signing out</a></li></ol></li><li class="section"><a href="sign-in-sign-out.html#sec-cucumber"><span class="number">8.3</span> Introduction to cucumber (optional)</a></li><li><ol><li class="subsection"><a href="sign-in-sign-out.html#sec-installation_and_setup"><span class="number">8.3.1</span> Installation and setup</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-features_and_steps"><span class="number">8.3.2</span> Features and steps</a></li><li class="subsection"><a href="sign-in-sign-out.html#sec-rspec_custom_matchers"><span class="number">8.3.3</span> Counterpoint: RSpec custom matchers</a></li></ol></li><li class="section"><a href="sign-in-sign-out.html#sec-8_4"><span class="number">8.4</span> Conclusion</a></li><li class="section"><a href="sign-in-sign-out.html#sec-sign_in_out_exercises"><span class="number">8.5</span> Exercises</a></li></ol></li><li class="chapter"><a href="updating-showing-and-deleting-users.html#top"><span class="number">Chapter 9</span> Updating, showing, and deleting users</a></li><li><ol><li class="section"><a href="updating-showing-and-deleting-users.html#sec-updating_users"><span class="number">9.1</span> Updating users</a></li><li><ol><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-edit_form"><span class="number">9.1.1</span> Edit form</a></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-unsuccessful_edits"><span class="number">9.1.2</span> Unsuccessful edits</a></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-successful_edits"><span class="number">9.1.3</span> Successful edits</a></li></ol></li><li class="section"><a href="updating-showing-and-deleting-users.html#sec-authorization"><span class="number">9.2</span> Authorization</a></li><li><ol><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-requiring_signed_in_users"><span class="number">9.2.1</span> Requiring signed-in users</a></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-requiring_the_right_user"><span class="number">9.2.2</span> Requiring the right user</a></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-friendly_forwarding"><span class="number">9.2.3</span> Friendly forwarding</a></li></ol></li><li class="section"><a href="updating-showing-and-deleting-users.html#sec-showing_all_users"><span class="number">9.3</span> Showing all users</a></li><li><ol><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-user_index"><span class="number">9.3.1</span> User index</a></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-sample_users"><span class="number">9.3.2</span> Sample users</a></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-pagination"><span class="number">9.3.3</span> Pagination</a></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-partial_refactoring"><span class="number">9.3.4</span> Partial refactoring</a></li></ol></li><li class="section"><a href="updating-showing-and-deleting-users.html#sec-destroying_users"><span class="number">9.4</span> Deleting users</a></li><li><ol><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-administrative_users"><span class="number">9.4.1</span> Administrative users</a></li><li><ol><li class="subsubsection"><a href="updating-showing-and-deleting-users.html#sec-revisiting_strong_parameters">Revisiting strong parameters</a></li></ol></li><li class="subsection"><a href="updating-showing-and-deleting-users.html#sec-the_destroy_action"><span class="number">9.4.2</span> The <tt>destroy</tt> action</a></li></ol></li><li class="section"><a href="updating-showing-and-deleting-users.html#sec-updating_and_deleting_users_conclusion"><span class="number">9.5</span> Conclusion</a></li><li class="section"><a href="updating-showing-and-deleting-users.html#sec-updating_deleting_exercises"><span class="number">9.6</span> Exercises</a></li></ol></li><li class="chapter"><a href="user-microposts.html#top"><span class="number">Chapter 10</span> User microposts</a></li><li><ol><li class="section"><a href="user-microposts.html#sec-a_micropost_model"><span class="number">10.1</span> A Micropost model</a></li><li><ol><li class="subsection"><a href="user-microposts.html#sec-the_basic_model"><span class="number">10.1.1</span> The basic model</a></li><li class="subsection"><a href="user-microposts.html#sec-first_micropost_validation"><span class="number">10.1.2</span> The first validation</a></li><li class="subsection"><a href="user-microposts.html#sec-user_micropost_associations"><span class="number">10.1.3</span> User/Micropost associations</a></li><li class="subsection"><a href="user-microposts.html#sec-ordering_and_dependency"><span class="number">10.1.4</span> Micropost refinements</a></li><li><ol><li class="subsubsection"><a href="user-microposts.html#sec-default_scope">Default scope</a></li><li class="subsubsection"><a href="user-microposts.html#sec-dependent_destroy">Dependent: destroy</a></li></ol></li><li class="subsection"><a href="user-microposts.html#sec-micropost_validations"><span class="number">10.1.5</span> Content validations</a></li></ol></li><li class="section"><a href="user-microposts.html#sec-showing_microposts"><span class="number">10.2</span> Showing microposts</a></li><li><ol><li class="subsection"><a href="user-microposts.html#sec-augmenting_the_user_show_page"><span class="number">10.2.1</span> Augmenting the user show page</a></li><li class="subsection"><a href="user-microposts.html#sec-sample_microposts"><span class="number">10.2.2</span> Sample microposts</a></li></ol></li><li class="section"><a href="user-microposts.html#sec-manipulating_microposts"><span class="number">10.3</span> Manipulating microposts</a></li><li><ol><li class="subsection"><a href="user-microposts.html#sec-access_control"><span class="number">10.3.1</span> Access control</a></li><li class="subsection"><a href="user-microposts.html#sec-creating_microposts"><span class="number">10.3.2</span> Creating microposts</a></li><li class="subsection"><a href="user-microposts.html#sec-a_proto_feed"><span class="number">10.3.3</span> A proto-feed</a></li><li class="subsection"><a href="user-microposts.html#sec-destroying_microposts"><span class="number">10.3.4</span> Destroying microposts</a></li></ol></li><li class="section"><a href="user-microposts.html#sec-10_4"><span class="number">10.4</span> Conclusion</a></li><li class="section"><a href="user-microposts.html#sec-micropost_exercises"><span class="number">10.5</span> Exercises</a></li></ol></li><li class="chapter"><a href="following-users.html#top"><span class="number">Chapter 11</span> Following users</a></li><li><ol><li class="section"><a href="following-users.html#sec-the_relationship_model"><span class="number">11.1</span> The Relationship model</a></li><li><ol><li class="subsection"><a href="following-users.html#sec-a_problem_with_the_data_model"><span class="number">11.1.1</span> A problem with the data model (and a solution)</a></li><li class="subsection"><a href="following-users.html#sec-relationship_user_associations"><span class="number">11.1.2</span> User/relationship associations</a></li><li class="subsection"><a href="following-users.html#sec-relationship_validations"><span class="number">11.1.3</span> Validations</a></li><li class="subsection"><a href="following-users.html#sec-following"><span class="number">11.1.4</span> Followed users</a></li><li class="subsection"><a href="following-users.html#sec-followers"><span class="number">11.1.5</span> Followers</a></li></ol></li><li class="section"><a href="following-users.html#sec-a_web_interface_for_following_and_followers"><span class="number">11.2</span> A web interface for following users</a></li><li><ol><li class="subsection"><a href="following-users.html#sec-sample_following_data"><span class="number">11.2.1</span> Sample following data</a></li><li class="subsection"><a href="following-users.html#sec-stats_and_a_follow_form"><span class="number">11.2.2</span> Stats and a follow form</a></li><li class="subsection"><a href="following-users.html#sec-following_and_followers_pages"><span class="number">11.2.3</span> Following and followers pages</a></li><li class="subsection"><a href="following-users.html#sec-a_working_follow_button_the_standard_way"><span class="number">11.2.4</span> A working follow button the standard way</a></li><li class="subsection"><a href="following-users.html#sec-a_working_follow_button_with_ajax"><span class="number">11.2.5</span> A working follow button with Ajax</a></li></ol></li><li class="section"><a href="following-users.html#sec-the_status_feed"><span class="number">11.3</span> The status feed</a></li><li><ol><li class="subsection"><a href="following-users.html#sec-motivation_and_strategy"><span class="number">11.3.1</span> Motivation and strategy</a></li><li class="subsection"><a href="following-users.html#sec-a_first_feed_implementation"><span class="number">11.3.2</span> A first feed implementation</a></li><li class="subsection"><a href="following-users.html#sec-scopes_subselects_and_a_lambda"><span class="number">11.3.3</span> Subselects</a></li><li class="subsection"><a href="following-users.html#sec-the_new_status_feed"><span class="number">11.3.4</span> The new status feed</a></li></ol></li><li class="section"><a href="following-users.html#sec-following_conclusion"><span class="number">11.4</span> Conclusion</a></li><li><ol><li class="subsection"><a href="following-users.html#sec-extensions_to_the_sample_application"><span class="number">11.4.1</span> Extensions to the sample application</a></li><li><ol><li class="subsubsection"><a href="following-users.html#sec-replies">Replies</a></li><li class="subsubsection"><a href="following-users.html#sec-messaging">Messaging</a></li><li class="subsubsection"><a href="following-users.html#sec-follower_notifications">Follower notifications</a></li><li class="subsubsection"><a href="following-users.html#sec-password_reminders">Password reminders</a></li><li class="subsubsection"><a href="following-users.html#sec-signup_confirmation">Signup confirmation</a></li><li class="subsubsection"><a href="following-users.html#sec-rss_feed">RSS feed</a></li><li class="subsubsection"><a href="following-users.html#sec-rest_api">REST API</a></li><li class="subsubsection"><a href="following-users.html#sec-search">Search</a></li></ol></li><li class="subsection"><a href="following-users.html#sec-guide_to_further_resources"><span class="number">11.4.2</span> Guide to further resources</a></li></ol></li><li class="section"><a href="following-users.html#sec-following_exercises"><span class="number">11.5</span> Exercises</a></li></ol></li></ol></div>
<div id="main_content"></div>
<p> <span class="preamble">
<span id="foreword">
<strong> Foreword</strong> <br />
</span>
</span></p>
<p>My former company (CD Baby) was one of the first to loudly switch to Ruby on Rails, and then even more loudly switch back to PHP (Google me to read about the drama). This book by Michael Hartl came so highly recommended that I had to try it, and the <em>Ruby on Rails Tutorial</em> is what I used to switch back to Rails again.</p>
<p>Though I’ve worked my way through many Rails books, this is the one that finally made me “get” it. Everything is done very much “the Rails way”—a way that felt very unnatural to me before, but now after doing this book finally feels natural. This is also the only Rails book that does test-driven development the entire time, an approach highly recommended by the experts but which has never been so clearly demonstrated before. Finally, by including Git, GitHub, and Heroku in the demo examples, the author really gives you a feel for what it’s like to do a real-world project. The tutorial’s code examples are not in isolation.</p>
<p>The linear narrative is such a great format. Personally, I powered through the <em>Rails Tutorial</em> in three long days, doing all the examples and challenges at the end of each chapter. Do it from start to finish, without jumping around, and you’ll get the ultimate benefit.</p>
<p>Enjoy!</p>
<p><a href="http://sivers.org/">Derek Sivers</a> (<a href="http://sivers.org/">sivers.org</a>) <br />
<em>Founder, CD Baby</em> <br /></p>
<p> <span class="preamble">
<strong> Acknowledgments</strong> <br />
</span></p>
<p>The <em>Ruby on Rails Tutorial</em> owes a lot to my previous Rails book, <em>RailsSpace</em>, and hence to my coauthor <a href="http://aure.com/">Aurelius Prochazka</a>. I’d like to thank Aure both for the work he did on that book and for his support of this one. I’d also like to thank Debra Williams Cauley, my editor on both <em>RailsSpace</em> and the <em>Ruby on Rails Tutorial</em>; as long as she keeps taking me to baseball games, I’ll keep writing books for her.</p>
<p>I’d like to acknowledge a long list of Rubyists who have taught and inspired me over the years: David Heinemeier Hansson, Yehuda Katz, Carl Lerche, Jeremy Kemper, Xavier Noria, Ryan Bates, Geoffrey Grosenbach, Peter Cooper, Matt Aimonetti, Gregg Pollack, Wayne E. Seguin, Amy Hoy, Dave Chelimsky, Pat Maddox, Tom Preston-Werner, Chris Wanstrath, Chad Fowler, Josh Susser, Obie Fernandez, Ian McFarland, Steven Bristol, Pratik Naik, Sarah Mei, Sarah Allen, Wolfram Arnold, Alex Chaffee, Giles Bowkett, Evan Dorn, Long Nguyen, James Lindenbaum, Adam Wiggins, Tikhon Bernstam, Ron Evans, Wyatt Greene, Miles Forrest, the good people at Pivotal Labs, the Heroku gang, the thoughtbot guys, and the GitHub crew. Finally, many, many readers—far too many to list—have contributed a huge number of bug reports and suggestions during the writing of this book, and I gratefully acknowledge their help in making it as good as it can be. <br /></p>
<p> <span class="preamble">
<span id="author">
<strong> About the author</strong> <br />
</span>
</span></p>
<p><a href="http://michaelhartl.com/">Michael Hartl</a> is the author of the <a href="http://ruby.railstutorial.org/"><em>Ruby on Rails Tutorial</em></a>, the leading introduction to web development with <a href="http://rubyonrails.org/">Ruby on Rails</a>. His prior experience includes writing and developing <em>RailsSpace</em>, an extremely obsolete Rails tutorial book, and developing Insoshi, a once-popular and now-obsolete social networking platform in Ruby on Rails. In 2011, Michael received a <a href="http://rubyheroes.com/heroes">Ruby Hero Award</a> for his contributions to the Ruby community. He is a graduate of <a href="http://college.harvard.edu/">Harvard College</a>, has a <a href="http://resolver.caltech.edu/CaltechETD:etd-05222003-161626">Ph.D. in Physics</a> from <a href="http://www.caltech.edu/">Caltech</a>, and is an alumnus of the <a href="http://ycombinator.com/">Y Combinator</a> entrepreneur program. <br /></p>
<p> <span id="license" class="preamble">
<strong> Copyright and license</strong> <br />
</span></p>
<p><em>Ruby on Rails Tutorial: Learn Web Development with Rails</em>. Copyright © 2013 by Michael Hartl. All source code in the <em>Ruby on Rails Tutorial</em> is available jointly under the <a href="http://opensource.org/licenses/MIT">MIT License</a> and the <a href="http://people.freebsd.org/~phk/">Beerware License</a>.</p>
<div class="code"><div class="highlight"><pre>The MIT License
Copyright (c) 2013 Michael Hartl
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
</pre></div>
</div>
<div class="code"><div class="highlight"><pre>/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* Michael Hartl wrote this code. As long as you retain this notice you
* can do whatever you want with this stuff. If we meet some day, and you think
* this stuff is worth it, you can buy me a beer in return.
* ----------------------------------------------------------------------------
*/
</pre></div>
</div>
<div id="top"></div>
<h1 class="chapter"><a id="sec-10" href="user-microposts.html#top" class="heading"><span class="number">Chapter 10</span> User microposts</a></h1>
<p><a class="ref" href="updating-showing-and-deleting-users.html#top">Chapter 9</a> saw the completion of the REST actions for the Users resource, so the time has finally come to add a second full resource: user <em>microposts</em>.<sup class="footnote" id="fnref-10_1"><a href="#fn-10_1">1</a></sup> These are short messages associated with a particular user, first seen in larval form in <a class="ref" href="a-demo-app.html#top">Chapter 2</a>. In this chapter, we will make a full-strength version of the sketch from <a class="ref" href="a-demo-app.html#sec-microposts_resource">Section 2.3</a> by constructing the Micropost data model, associating it with the User model using the <code>has_many</code> and <code>belongs_to</code> methods, and then making the forms and partials needed to manipulate and display the results. In <a class="ref" href="following-users.html#top">Chapter 11</a>, we’ll complete our tiny Twitter clone by adding the notion of <em>following</em> users in order to receive a <em>feed</em> of their microposts.</p>
<p>If you’re using Git for version control, I suggest making a topic branch as usual:</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> git checkout -b user-microposts
</pre></div>
</div>
<div class="label" id="sec-a_micropost_model"></div>
<h2><a id="sec-10_1" href="user-microposts.html#sec-a_micropost_model" class="heading"><span class="number">10.1</span> A Micropost model</a></h2>
<p>We begin the Microposts resource by creating a Micropost model, which captures the essential characteristics of microposts. What follows builds on the work from <a class="ref" href="a-demo-app.html#sec-microposts_resource">Section 2.3</a>; as with the model in that section, our new Micropost model will include data validations and an association with the User model. Unlike that model, the present Micropost model will be fully tested, and will also have a default <em>ordering</em> and automatic <em>destruction</em> if its parent user is destroyed.</p>
<div class="label" id="sec-the_basic_model"></div>
<h3><a id="sec-10_1_1" href="user-microposts.html#sec-the_basic_model" class="heading"><span class="number">10.1.1</span> The basic model</a></h3>
<p>The Micropost model needs only two attributes: a <code>content</code> attribute to hold the micropost’s content,<sup class="footnote" id="fnref-10_2"><a href="#fn-10_2">2</a></sup> and a <code>user_id</code> to associate a micropost with a particular user. As with the case of the User model (<a class="ref" href="modeling-users.html#code-generate_user_model">Listing 6.1</a>), we generate it using <code>generate model</code>:</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> rails generate model Micropost content:string user_id:integer
</pre></div>
</div>
<p>It’s possible that this will generate a Micropost factory, which you should remove since we’ll be making one later by hand (<a class="ref" href="user-microposts.html#sec-ordering_and_dependency">Section 10.1.4</a>):</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> rm -f spec/factories/microposts.rb
</pre></div>
</div>
<p>The generate command produces a migration to create a <code>microposts</code> table in the database (<a class="ref" href="user-microposts.html#code-micropost_migration">Listing 10.1</a>); compare it to the analogous migration for the <code>users</code> table from <a class="ref" href="modeling-users.html#code-users_migration">Listing 6.2</a>.</p>
<div class="label" id="code-micropost_migration"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.1.</span> <span class="description">The Micropost migration. (Note the index on <code>user_id</code> and <code>created_at</code>.) <br /> <code>db/migrate/[timestamp]_create_microposts.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="k">class</span> <span class="nc">CreateMicroposts</span> <span class="o"><</span> <span class="ss">ActiveRecord::Migration</span>
<span class="k">def</span> <span class="nf">change</span>
<span class="n">create_table</span> <span class="ss">:microposts</span> <span class="k">do</span> <span class="o">|</span><span class="n">t</span><span class="o">|</span>
<span class="n">t</span><span class="o">.</span><span class="n">string</span> <span class="ss">:content</span>
<span class="n">t</span><span class="o">.</span><span class="n">integer</span> <span class="ss">:user_id</span>
<span class="n">t</span><span class="o">.</span><span class="n">timestamps</span>
<span class="k">end</span>
<span class="n">add_index</span> <span class="ss">:microposts</span><span class="p">,</span> <span class="o">[</span><span class="ss">:user_id</span><span class="p">,</span> <span class="ss">:created_at</span><span class="o">]</span>
<span class="k">end</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>Note that, since we expect to retrieve all the microposts associated with a given user id in reverse order of creation, <a class="ref" href="user-microposts.html#code-micropost_migration">Listing 10.1</a> adds an index (<a class="ref" href="modeling-users.html#sidebar-database_indices">Box 6.2</a>) on the <code>user_id</code> and <code>created_at</code> columns:</p>
<div class="code"><div class="highlight"><pre><span class="n">add_index</span> <span class="ss">:microposts</span><span class="p">,</span> <span class="o">[</span><span class="ss">:user_id</span><span class="p">,</span> <span class="ss">:created_at</span><span class="o">]</span>
</pre></div>
</div>
<p>By including both the <code>user_id</code> and <code>created_at</code> columns as an array, we arrange for Rails to create a <em>multiple key index</em>, which means that Active Record uses <em>both</em> keys at the same time. Note also the <code>t.timestamps</code> line, which (as mentioned in <a class="ref" href="modeling-users.html#sec-database_migrations">Section 6.1.1</a>) adds the magic <code>created_at</code> and <code>updated_at</code> columns. We’ll put the <code>created_at</code> column to work in <a class="ref" href="user-microposts.html#sec-ordering_and_dependency">Section 10.1.4</a> and <a class="ref" href="user-microposts.html#sec-augmenting_the_user_show_page">Section 10.2.1</a>.</p>
<p>We’ll start with some minimal tests for the Micropost model based on the analogous tests for the User model (<a class="ref" href="modeling-users.html#code-user_spec">Listing 6.5</a>). In particular, we verify that a micropost object responds to the <code>content</code> and <code>user_id</code> attributes, as shown in <a class="ref" href="user-microposts.html#code-initial_micropost_spec">Listing 10.2</a>.</p>
<div class="label" id="code-initial_micropost_spec"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.2.</span> <span class="description">The initial Micropost spec. <br /> <code>spec/models/micropost_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="no">Micropost</span> <span class="k">do</span>
<span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="k">do</span>
<span class="c1"># This code is not idiomatically correct.</span>
<span class="vi">@micropost</span> <span class="o">=</span> <span class="no">Micropost</span><span class="o">.</span><span class="n">new</span><span class="p">(</span><span class="ss">content:</span> <span class="s2">"Lorem ipsum"</span><span class="p">,</span> <span class="ss">user_id:</span> <span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)</span>
<span class="k">end</span>
<span class="n">subject</span> <span class="p">{</span> <span class="vi">@micropost</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:content</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:user_id</span><span class="p">)</span> <span class="p">}</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>We can get these tests to pass by running the microposts migration and preparing the test database:</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> bundle <span class="nb">exec </span>rake db:migrate
<span class="gp">$</span> bundle <span class="nb">exec </span>rake <span class="nb">test</span>:prepare
</pre></div>
</div>
<p>The result is a Micropost model with the structure shown in <a class="ref" href="user-microposts.html#fig-micropost_model">Figure 10.1</a>.</p>
<div class="label" id="fig-micropost_model"></div>
<div class="figure"><div class="center"><span class="graphic"><img src="images/figures/micropost_model.png" alt="micropost_model" /></span></div><div class="caption"><span class="header">Figure 10.1: </span><span class="description">The Micropost data model.</span></div></div>
<p>You should verify that the tests pass:</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> bundle <span class="nb">exec </span>rspec spec/models/micropost_spec.rb
</pre></div>
</div>
<p>Even though the tests are passing, you might have noticed this code:</p>
<div class="code"><div class="highlight"><pre><span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="k">do</span>
<span class="c1"># This code is not idiomatically correct.</span>
<span class="vi">@micropost</span> <span class="o">=</span> <span class="no">Micropost</span><span class="o">.</span><span class="n">new</span><span class="p">(</span><span class="ss">content:</span> <span class="s2">"Lorem ipsum"</span><span class="p">,</span> <span class="ss">user_id:</span> <span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)</span>
<span class="k">end</span>
</pre></div>
</div>
<p>The comment indicates that the code in the <code>before</code> block is not idiomatically correct. That is, it works, but it’s not the Rails way. See if you can guess why. We’ll see the answer in <a class="ref" href="user-microposts.html#sec-user_micropost_associations">Section 10.1.3</a>.</p>
<div class="label" id="sec-first_micropost_validation"></div>
<h3><a id="sec-10_1_2" href="user-microposts.html#sec-first_micropost_validation" class="heading"><span class="number">10.1.2</span> The first validation</a></h3>
<p>One of the necessary aspects of the Micropost model is the presence of a user id to indicate which user made the micropost. The idiomatically correct way to do this is to use Active Record <em>associations</em>, which we’ll implement in <a class="ref" href="user-microposts.html#sec-user_micropost_associations">Section 10.1.3</a>. Since this will involve a minor refactoring, in this section we’ll write a test to catch any future regressions.</p>
<p>As shown in <a class="ref" href="user-microposts.html#code-micropost_validity_test">Listing 10.3</a>, the validation test for user id just sets the id to <code>nil</code> and then checks that the resulting micropost is invalid. (Compare with the User model tests in <a class="ref" href="modeling-users.html#code-failing_validates_name_spec">Listing 6.8</a>.)</p>
<div class="label" id="code-micropost_validity_test"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.3.</span> <span class="description">Tests for the validity of a new micropost. <br /> <code>spec/models/micropost_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="no">Micropost</span> <span class="k">do</span>
<span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="k">do</span>
<span class="c1"># This code is not idiomatically correct.</span>
<span class="vi">@micropost</span> <span class="o">=</span> <span class="no">Micropost</span><span class="o">.</span><span class="n">new</span><span class="p">(</span><span class="ss">content:</span> <span class="s2">"Lorem ipsum"</span><span class="p">,</span> <span class="ss">user_id:</span> <span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)</span>
<span class="k">end</span>
<span class="n">subject</span> <span class="p">{</span> <span class="vi">@micropost</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:content</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:user_id</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">be_valid</span> <span class="p">}</span>
<span class="n">describe</span> <span class="s2">"when user_id is not present"</span> <span class="k">do</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span><span class="o">.</span><span class="n">user_id</span> <span class="o">=</span> <span class="kp">nil</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should_not</span> <span class="n">be_valid</span> <span class="p">}</span>
<span class="k">end</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>This code requires that the micropost be valid and tests for the presence of the <code>user_id</code> attribute. We can get these tests to pass with the simple presence validation shown in <a class="ref" href="user-microposts.html#code-micropost_user_id_validation">Listing 10.4</a>.</p>
<div class="label" id="code-micropost_user_id_validation"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.4.</span> <span class="description">A validation for the micropost’s <code>user_id</code>. <br /> <code>app/models/micropost.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="k">class</span> <span class="nc">Micropost</span> <span class="o"><</span> <span class="ss">ActiveRecord::Base</span>
<span class="n">validates</span> <span class="ss">:user_id</span><span class="p">,</span> <span class="ss">presence:</span> <span class="kp">true</span>
<span class="k">end</span>
</pre></div>
</div></div>
<div class="label" id="sec-user_micropost_associations"></div>
<h3><a id="sec-10_1_3" href="user-microposts.html#sec-user_micropost_associations" class="heading"><span class="number">10.1.3</span> User/Micropost associations</a></h3>
<p>When constructing data models for web applications, it is essential to be able to make <em>associations</em> between individual models. In the present case, each micropost is associated with one user, and each user is associated with (potentially) many microposts—a relationship seen briefly in <a class="ref" href="a-demo-app.html#sec-demo_user_has_many_microposts">Section 2.3.3</a> and shown schematically in <a class="ref" href="user-microposts.html#fig-micropost_belongs_to_user">Figure 10.2</a> and <a class="ref" href="user-microposts.html#fig-user_has_many_microposts">Figure 10.3</a>. As part of implementing these associations, we’ll write tests for the Micropost model and add a couple of tests to the User model.</p>
<div class="label" id="fig-micropost_belongs_to_user"></div>
<div class="figure"><div class="center"><span class="graphic"><img src="images/figures/micropost_belongs_to_user.png" alt="micropost_belongs_to_user" /></span></div><div class="caption"><span class="header">Figure 10.2: </span><span class="description">The <code>belongs_to</code> relationship between a micropost and its user.</span></div></div>
<div class="label" id="fig-user_has_many_microposts"></div>
<div class="figure"><div class="center"><span class="graphic"><img src="images/figures/user_has_many_microposts.png" alt="user_has_many_microposts" /></span></div><div class="caption"><span class="header">Figure 10.3: </span><span class="description">The <code>has_many</code> relationship between a user and its microposts.</span></div></div>
<p>Using the <code>belongs_to</code>/<code>has_many</code> association defined in this section, Rails constructs the methods shown in <a class="ref" href="user-microposts.html#table-association_methods">Table 10.1</a>.</p>
<div class="label" id="table-association_methods"></div>
<div class="table"><div class="center">
<table class="tabular"><tr><th class="align_left"><strong>Method</strong></th><th class="align_left"><strong>Purpose</strong></th></tr><tr class="top_bar"><td class="align_left"><code>micropost.user</code></td><td class="align_left">Return the User object associated with the micropost.</td></tr><tr><td class="align_left"><code>user.microposts</code></td><td class="align_left">Return an array of the user’s microposts.</td></tr><tr><td class="align_left"><code>user.microposts.create(arg)</code></td><td class="align_left">Create a micropost (<code>user_id = user.id</code>).</td></tr><tr><td class="align_left"><code>user.microposts.create!(arg)</code></td><td class="align_left">Create a micropost (exception on failure).</td></tr><tr><td class="align_left"><code>user.microposts.build(arg)</code></td><td class="align_left">Return a new Micropost object (<code>user_id = user.id</code>).</td></tr></table></div><div class="caption"><span class="header">Table 10.1: </span><span class="description">A summary of user/micropost association methods.</span></div></div>
<p>Note from <a class="ref" href="user-microposts.html#table-association_methods">Table 10.1</a> that instead of</p>
<div class="code"><div class="highlight"><pre><span class="no">Micropost</span><span class="o">.</span><span class="n">create</span>
<span class="no">Micropost</span><span class="o">.</span><span class="n">create!</span>
<span class="no">Micropost</span><span class="o">.</span><span class="n">new</span>
</pre></div>
</div>
<p>we have</p>
<div class="code"><div class="highlight"><pre><span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">create</span>
<span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">create!</span>
<span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">build</span>
</pre></div>
</div>
<p>This pattern is the canonical way to make a micropost: <em>through</em> its association with a user. When a new micropost is made in this way, its <code>user_id</code> is <em>automatically</em> set to the right value. In particular, we can replace the code</p>
<div class="code"><div class="highlight"><pre><span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="k">do</span>
<span class="c1"># This code is not idiomatically correct.</span>
<span class="vi">@micropost</span> <span class="o">=</span> <span class="no">Micropost</span><span class="o">.</span><span class="n">new</span><span class="p">(</span><span class="ss">content:</span> <span class="s2">"Lorem ipsum"</span><span class="p">,</span> <span class="ss">user_id:</span> <span class="n">user</span><span class="o">.</span><span class="n">id</span><span class="p">)</span>
<span class="k">end</span>
</pre></div>
</div>
<p>from <a class="ref" href="user-microposts.html#code-micropost_validity_test">Listing 10.3</a> with</p>
<div class="code"><div class="highlight"><pre><span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span> <span class="o">=</span> <span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">build</span><span class="p">(</span><span class="ss">content:</span> <span class="s2">"Lorem ipsum"</span><span class="p">)</span> <span class="p">}</span>
</pre></div>
</div>
<p>Once we define the proper associations, the resulting <code>@micropost</code> variable will automatically have <code>user_id</code> equal to its associated user.</p>
<p>As seen in <a class="ref" href="user-microposts.html#table-association_methods">Table 10.1</a>, another result of the user/micropost association is <code>micropost.user</code>, which simply returns the micropost’s user. We can test this with the <code>it</code> and <code>its</code> methods as follows:</p>
<div class="code"><div class="highlight"><pre><span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">its</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="n">should</span> <span class="n">eq</span> <span class="n">user</span> <span class="p">}</span>
</pre></div>
</div>
<p>The resulting Micropost model tests are shown in <a class="ref" href="user-microposts.html#code-micropost_belongs_to_user_spec">Listing 10.5</a>.</p>
<div class="label" id="code-micropost_belongs_to_user_spec"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.5.</span> <span class="description">Tests for the micropost’s user association. <br /> <code>spec/models/micropost_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="no">Micropost</span> <span class="k">do</span>
<span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span> <span class="o">=</span> <span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">build</span><span class="p">(</span><span class="ss">content:</span> <span class="s2">"Lorem ipsum"</span><span class="p">)</span> <span class="p">}</span>
<span class="n">subject</span> <span class="p">{</span> <span class="vi">@micropost</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:content</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:user_id</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">its</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="n">should</span> <span class="n">eq</span> <span class="n">user</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">be_valid</span> <span class="p">}</span>
<span class="n">describe</span> <span class="s2">"when user_id is not present"</span> <span class="k">do</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span><span class="o">.</span><span class="n">user_id</span> <span class="o">=</span> <span class="kp">nil</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should_not</span> <span class="n">be_valid</span> <span class="p">}</span>
<span class="k">end</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>On the User model side of the association, we’ll defer the more detailed tests to <a class="ref" href="user-microposts.html#sec-ordering_and_dependency">Section 10.1.4</a>; for now, we’ll simply test for the presence of a <code>microposts</code> attribute (<a class="ref" href="user-microposts.html#code-user_has_many_microposts_spec">Listing 10.6</a>).</p>
<div class="label" id="code-user_has_many_microposts_spec"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.6.</span> <span class="description">A test for the user’s <code>microposts</code> attribute. <br /> <code>spec/models/user_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="no">User</span> <span class="k">do</span>
<span class="n">before</span> <span class="k">do</span>
<span class="vi">@user</span> <span class="o">=</span> <span class="no">User</span><span class="o">.</span><span class="n">new</span><span class="p">(</span><span class="nb">name</span><span class="p">:</span> <span class="s2">"Example User"</span><span class="p">,</span> <span class="ss">email:</span> <span class="s2">"[email protected]"</span><span class="p">,</span>
<span class="ss">password:</span> <span class="s2">"foobar"</span><span class="p">,</span> <span class="ss">password_confirmation:</span> <span class="s2">"foobar"</span><span class="p">)</span>
<span class="k">end</span>
<span class="n">subject</span> <span class="p">{</span> <span class="vi">@user</span> <span class="p">}</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:admin</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">respond_to</span><span class="p">(</span><span class="ss">:microposts</span><span class="p">)</span> <span class="p">}</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>After all that work, the code to implement the association is almost comically short: we can get the tests in both <a class="ref" href="user-microposts.html#code-micropost_belongs_to_user_spec">Listing 10.5</a> and <a class="ref" href="user-microposts.html#code-user_has_many_microposts_spec">Listing 10.6</a> to pass by adding just two lines: <code>belongs_to :user</code> (<a class="ref" href="user-microposts.html#code-micropost_belongs_to_user">Listing 10.7</a>) and <code>has_many :microposts</code> (<a class="ref" href="user-microposts.html#code-user_has_many_microposts">Listing 10.8</a>).</p>
<div class="label" id="code-micropost_belongs_to_user"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.7.</span> <span class="description">A micropost <code>belongs_to</code> a user. <br /> <code>app/models/micropost.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="k">class</span> <span class="nc">Micropost</span> <span class="o"><</span> <span class="ss">ActiveRecord::Base</span>
<span class="n">belongs_to</span> <span class="ss">:user</span>
<span class="n">validates</span> <span class="ss">:user_id</span><span class="p">,</span> <span class="ss">presence:</span> <span class="kp">true</span>
<span class="k">end</span>
</pre></div>
</div></div>
<div class="label" id="code-user_has_many_microposts"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.8.</span> <span class="description">A user <code>has_many</code> microposts. <br /> <code>app/models/user.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="k">class</span> <span class="nc">User</span> <span class="o"><</span> <span class="ss">ActiveRecord::Base</span>
<span class="n">has_many</span> <span class="ss">:microposts</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>At this point, you should compare the entries in <a class="ref" href="user-microposts.html#table-association_methods">Table 10.1</a> with the code in <a class="ref" href="user-microposts.html#code-micropost_belongs_to_user_spec">Listing 10.5</a> and <a class="ref" href="user-microposts.html#code-user_has_many_microposts_spec">Listing 10.6</a> to satisfy yourself that you understand the basic nature of the associations. You should also check that the tests pass:</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> bundle <span class="nb">exec </span>rspec spec/models
</pre></div>
</div>
<div class="label" id="sec-ordering_and_dependency"></div>
<h3><a id="sec-10_1_4" href="user-microposts.html#sec-ordering_and_dependency" class="heading"><span class="number">10.1.4</span> Micropost refinements</a></h3>
<p>The test in <a class="ref" href="user-microposts.html#code-user_has_many_microposts_spec">Listing 10.6</a> of the <code>has_many</code> association doesn’t test for much—it merely verifies the <em>existence</em> of a <code>microposts</code> attribute. In this section, we’ll add <em>ordering</em> and <em>dependency</em> to microposts, while also testing that the <code>user.microposts</code> method actually returns an array of microposts.</p>
<p>We will need to construct some microposts in the User model test, which means that we should make a micropost factory at this point. To do this, we need a way to make an association in Factory Girl. Happily, this is easy, as seen in <a class="ref" href="user-microposts.html#code-micropost_factory">Listing 10.9</a>.</p>
<div class="label" id="code-micropost_factory"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.9.</span> <span class="description">The complete factory file, including a new factory for microposts. <br /> <code>spec/factories.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="no">FactoryGirl</span><span class="o">.</span><span class="n">define</span> <span class="k">do</span>
<span class="n">factory</span> <span class="ss">:user</span> <span class="k">do</span>
<span class="n">sequence</span><span class="p">(</span><span class="ss">:name</span><span class="p">)</span> <span class="p">{</span> <span class="o">|</span><span class="n">n</span><span class="o">|</span> <span class="s2">"Person </span><span class="si">#{</span><span class="n">n</span><span class="si">}</span><span class="s2">"</span> <span class="p">}</span>
<span class="n">sequence</span><span class="p">(</span><span class="ss">:email</span><span class="p">)</span> <span class="p">{</span> <span class="o">|</span><span class="n">n</span><span class="o">|</span> <span class="s2">"person_</span><span class="si">#{</span><span class="n">n</span><span class="si">}</span><span class="s2">@example.com"</span><span class="p">}</span>
<span class="n">password</span> <span class="s2">"foobar"</span>
<span class="n">password_confirmation</span> <span class="s2">"foobar"</span>
<span class="n">factory</span> <span class="ss">:admin</span> <span class="k">do</span>
<span class="n">admin</span> <span class="kp">true</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="n">factory</span> <span class="ss">:micropost</span> <span class="k">do</span>
<span class="n">content</span> <span class="s2">"Lorem ipsum"</span>
<span class="n">user</span>
<span class="k">end</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>Here we tell Factory Girl about the micropost’s associated user just by including a user in the definition of the factory:</p>
<div class="code"><div class="highlight"><pre><span class="n">factory</span> <span class="ss">:micropost</span> <span class="k">do</span>
<span class="n">content</span> <span class="s2">"Lorem ipsum"</span>
<span class="n">user</span>
<span class="k">end</span>
</pre></div>
</div>
<p>As we’ll see in the next section, this allows us to define factory microposts as follows:</p>
<div class="code"><div class="highlight"><pre><span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="vi">@user</span><span class="p">,</span> <span class="ss">created_at:</span> <span class="mi">1</span><span class="o">.</span><span class="n">day</span><span class="o">.</span><span class="n">ago</span><span class="p">)</span>
</pre></div>
</div>
<div class="label" id="sec-default_scope"></div>
<h4><a id="sec-10_1_4_1" href="user-microposts.html#sec-default_scope" class="heading">Default scope</a></h4>
<p>By default, using <code>user.microposts</code> to pull a user’s microposts from the database makes no guarantees about the order of the posts, but (following the convention of blogs and Twitter) we want the microposts to come out in reverse order of when they were created, i.e., most recent first. To test this ordering, we first create a couple of microposts as follows:</p>
<div class="code"><div class="highlight"><pre><span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="vi">@user</span><span class="p">,</span> <span class="ss">created_at:</span> <span class="mi">1</span><span class="o">.</span><span class="n">day</span><span class="o">.</span><span class="n">ago</span><span class="p">)</span>
<span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="vi">@user</span><span class="p">,</span> <span class="ss">created_at:</span> <span class="mi">1</span><span class="o">.</span><span class="n">hour</span><span class="o">.</span><span class="n">ago</span><span class="p">)</span>
</pre></div>
</div>
<p>Here we indicate (using the time helpers discussed in <a class="ref" href="sign-in-sign-out.html#sidebar-time_helpers">Box 8.1</a>) that the second post was created more recently, i.e., <code>1.hour.ago</code>, while the first post was created <code>1.day.ago</code>. Note how convenient the use of Factory Girl is: we can set <code>created_at</code> manually, which Active Record won’t allow us to do. (Recall that <code>created_at</code> and <code>updated_at</code> are “magic” columns, automatically set to the proper creation and update timestamps, so any explicit initialization values are overwritten by the magic.)</p>
<p>Most database adapters (including the one for SQLite) return the microposts in order of their ids, so we can arrange for an initial test that almost certainly fails using the code in <a class="ref" href="user-microposts.html#code-micropost_ordering_test">Listing 10.10</a>. This uses the <code>let!</code> (read “let bang”) method in place of <code>let</code>; the reason is that <code>let</code> variables are <em>lazy</em>, meaning that they only spring into existence when referenced. The problem is that we want the microposts to exist immediately, so that the timestamps are in the right order and so that <code>@user.microposts</code> isn’t empty. We accomplish this with <code>let!</code>, which forces the corresponding variable to come into existence immediately.</p>
<div class="label" id="code-micropost_ordering_test"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.10.</span> <span class="description">Testing the order of a user’s microposts. <br /> <code>spec/models/user_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="no">User</span> <span class="k">do</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="n">describe</span> <span class="s2">"micropost associations"</span> <span class="k">do</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@user</span><span class="o">.</span><span class="n">save</span> <span class="p">}</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:older_micropost</span><span class="p">)</span> <span class="k">do</span>
<span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="vi">@user</span><span class="p">,</span> <span class="ss">created_at:</span> <span class="mi">1</span><span class="o">.</span><span class="n">day</span><span class="o">.</span><span class="n">ago</span><span class="p">)</span>
<span class="k">end</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:newer_micropost</span><span class="p">)</span> <span class="k">do</span>
<span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="vi">@user</span><span class="p">,</span> <span class="ss">created_at:</span> <span class="mi">1</span><span class="o">.</span><span class="n">hour</span><span class="o">.</span><span class="n">ago</span><span class="p">)</span>
<span class="k">end</span>
<span class="n">it</span> <span class="s2">"should have the right microposts in the right order"</span> <span class="k">do</span>
<span class="n">expect</span><span class="p">(</span><span class="vi">@user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">to_a</span><span class="p">)</span><span class="o">.</span><span class="n">to</span> <span class="n">eq</span> <span class="o">[</span><span class="n">newer_micropost</span><span class="p">,</span> <span class="n">older_micropost</span><span class="o">]</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>The key line here is</p>
<div class="code"><div class="highlight"><pre><span class="n">expect</span><span class="p">(</span><span class="vi">@user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">to_a</span><span class="p">)</span><span class="o">.</span><span class="n">to</span> <span class="n">eq</span> <span class="o">[</span><span class="n">newer_micropost</span><span class="p">,</span> <span class="n">older_micropost</span><span class="o">]</span>
</pre></div>
</div>
<p>indicating that the posts should be ordered newest first. This should fail because by default the posts will be ordered by id, i.e., <code>[older_micropost, newer_micropost]</code>. This test also verifies the basic correctness of the <code>has_many</code> association itself, by checking (as indicated in <a class="ref" href="user-microposts.html#table-association_methods">Table 10.1</a>) that <code>user.microposts</code> effectively returns an array of microposts. The <code>to_a</code> method, discussed before in <a class="ref" href="rails-flavored-ruby.html#sec-arrays_and_ranges">Section 4.3.1</a>, converts <code>@user.microposts</code> from its default state (which happens to be an Active Record “collection proxy”) to a proper array appropriate for comparison with the one we constructed by hand.</p>
<p>To get the ordering test to pass, we use a Rails facility called <code>default_scope</code> with an <code>order</code> argument, as shown in <a class="ref" href="user-microposts.html#code-micropost_ordering">Listing 10.11</a>. (This is our first example of the notion of <em>scope</em>. We will learn about scope in a more general context in <a class="ref" href="following-users.html#top">Chapter 11</a>.)</p>
<div class="label" id="code-micropost_ordering"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.11.</span> <span class="description">Ordering the microposts with <code>default_scope</code>. <br /> <code>app/models/micropost.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="k">class</span> <span class="nc">Micropost</span> <span class="o"><</span> <span class="ss">ActiveRecord::Base</span>
<span class="n">belongs_to</span> <span class="ss">:user</span>
<span class="n">default_scope</span> <span class="o">-></span> <span class="p">{</span> <span class="n">order</span><span class="p">(</span><span class="s1">'created_at DESC'</span><span class="p">)</span> <span class="p">}</span>
<span class="n">validates</span> <span class="ss">:user_id</span><span class="p">,</span> <span class="ss">presence:</span> <span class="kp">true</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>The order here is <code>’created_at DESC’</code>, where <code>DESC</code> is SQL for “descending”, i.e., in descending order from newest to oldest.</p>
<p>As of Rails 4.0, all scopes take an anonymous function that returns the criteria desired for the scope, mainly so that the scope need not be evaluated immediately, but rather can be loaded later on an as-needed basis (so-called <em>lazy evaluation</em>). In the present case, this function is</p>
<div class="code"><div class="highlight"><pre><span class="o">-></span> <span class="p">{</span> <span class="n">order</span><span class="p">(</span><span class="s1">'created_at DESC'</span><span class="p">)</span> <span class="p">}</span>
</pre></div>
</div>
<p>The syntax for this kind of object, called a <em>Proc</em> (procedure) or <em>lambda</em>, is the arrow <code>-></code>. It takes in a block (<a class="ref" href="rails-flavored-ruby.html#sec-blocks">Section 4.3.2</a>) and then evaluates it when called with the <code>call</code> method. We can see how it works at the console:</p>
<div class="code"><div class="highlight"><pre><span class="gp">></span>> -> <span class="o">{</span> puts <span class="s2">"foo"</span> <span class="o">}</span>
<span class="go">=> #<Proc:0x007fab938d0108@(irb):1 (lambda)></span>
<span class="gp">></span>> -> <span class="o">{</span> puts <span class="s2">"foo"</span> <span class="o">}</span>.call
<span class="go">foo</span>
<span class="go">=> nil</span>
</pre></div>
</div>
<p>(Procs are a somewhat advanced Ruby topic, so don’t worry if they don’t make sense right away.)</p>
<div class="label" id="sec-dependent_destroy"></div>
<h4><a id="sec-10_1_4_2" href="user-microposts.html#sec-dependent_destroy" class="heading">Dependent: destroy</a></h4>
<p>Apart from proper ordering, there is a second refinement we’d like to add to microposts. Recall from <a class="ref" href="updating-showing-and-deleting-users.html#sec-destroying_users">Section 9.4</a> that site administrators have the power to <em>destroy</em> users. It stands to reason that, if a user is destroyed, the user’s microposts should be destroyed as well. We can test for this by first destroying a micropost’s user and then verifying that the associated microposts are no longer in the database.</p>
<p>In order to test destroying microposts properly, we first need to capture a given user’s posts in a local variable, and then destroy the user. A straighforward implementation looks like this:</p>
<div class="code"><div class="highlight"><pre><span class="n">microposts</span> <span class="o">=</span> <span class="vi">@user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">to_a</span>
<span class="vi">@user</span><span class="o">.</span><span class="n">destroy</span>
<span class="n">expect</span><span class="p">(</span><span class="n">microposts</span><span class="p">)</span><span class="o">.</span><span class="n">not_to</span> <span class="n">be_empty</span>
<span class="n">microposts</span><span class="o">.</span><span class="n">each</span> <span class="k">do</span> <span class="o">|</span><span class="n">micropost</span><span class="o">|</span>
<span class="c1"># Make sure the micropost doesn't appear in the database.</span>
<span class="k">end</span>
</pre></div>
</div>
<p>Here the call to <code>to_a</code> effectively makes a copy of the microposts, and we’ve included the line</p>
<div class="code"><div class="highlight"><pre><span class="n">expect</span><span class="p">(</span><span class="n">microposts</span><span class="p">)</span><span class="o">.</span><span class="n">not_to</span> <span class="n">be_empty</span>
</pre></div>
</div>
<p>as a safety check to catch any errors should the <code>to_a</code> ever be accidentally removed. The issue is that, without <code>to_a</code>, destroying the user would destroy the posts in the <code>microposts</code> variable, and as a result</p>
<div class="code"><div class="highlight"><pre><span class="n">microposts</span><span class="o">.</span><span class="n">each</span> <span class="k">do</span> <span class="o">|</span><span class="n">micropost</span><span class="o">|</span>
<span class="c1"># Make sure the micropost doesn't appear in the database.</span>
<span class="k">end</span>
</pre></div>
</div>
<p>wouldn’t actually test anything because <code>microposts</code> would be empty.</p>
<p>We can express the expectation that the microposts don’t appear in the database as follows:</p>
<div class="code"><div class="highlight"><pre><span class="n">microposts</span><span class="o">.</span><span class="n">each</span> <span class="k">do</span> <span class="o">|</span><span class="n">micropost</span><span class="o">|</span>
<span class="n">expect</span><span class="p">(</span><span class="no">Micropost</span><span class="o">.</span><span class="n">where</span><span class="p">(</span><span class="nb">id</span><span class="p">:</span> <span class="n">micropost</span><span class="o">.</span><span class="n">id</span><span class="p">))</span><span class="o">.</span><span class="n">to</span> <span class="n">be_empty</span>
<span class="k">end</span>
</pre></div>
</div>
<p>Here we have used <code>Micropost.where</code> instead of <code>Micropost.find</code> because it returns an empty object if the record is not found instead of raising an exception, which is a little easier to test. (In case you’re curious, the code</p>
<div class="code"><div class="highlight"><pre><span class="n">expect</span> <span class="k">do</span>
<span class="no">Micropost</span><span class="o">.</span><span class="n">find</span><span class="p">(</span><span class="n">micropost</span><span class="p">)</span>
<span class="k">end</span><span class="o">.</span><span class="n">to</span> <span class="n">raise_error</span><span class="p">(</span><span class="ss">ActiveRecord::RecordNotFound</span><span class="p">)</span>
</pre></div>
</div>
<p>does the trick in this case.)</p>
<p>Putting everything together leads to the code in <a class="ref" href="user-microposts.html#code-micropost_dependency_test">Listing 10.12</a>.</p>
<div class="label" id="code-micropost_dependency_test"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.12.</span> <span class="description">Testing that microposts are destroyed when users are. <br /> <code>spec/models/user_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="no">User</span> <span class="k">do</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="n">describe</span> <span class="s2">"micropost associations"</span> <span class="k">do</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@user</span><span class="o">.</span><span class="n">save</span> <span class="p">}</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:older_micropost</span><span class="p">)</span> <span class="k">do</span>
<span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="vi">@user</span><span class="p">,</span> <span class="ss">created_at:</span> <span class="mi">1</span><span class="o">.</span><span class="n">day</span><span class="o">.</span><span class="n">ago</span><span class="p">)</span>
<span class="k">end</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:newer_micropost</span><span class="p">)</span> <span class="k">do</span>
<span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="vi">@user</span><span class="p">,</span> <span class="ss">created_at:</span> <span class="mi">1</span><span class="o">.</span><span class="n">hour</span><span class="o">.</span><span class="n">ago</span><span class="p">)</span>
<span class="k">end</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="n">it</span> <span class="s2">"should destroy associated microposts"</span> <span class="k">do</span>
<span class="n">microposts</span> <span class="o">=</span> <span class="vi">@user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">to_a</span>
<span class="vi">@user</span><span class="o">.</span><span class="n">destroy</span>
<span class="n">expect</span><span class="p">(</span><span class="n">microposts</span><span class="p">)</span><span class="o">.</span><span class="n">not_to</span> <span class="n">be_empty</span>
<span class="n">microposts</span><span class="o">.</span><span class="n">each</span> <span class="k">do</span> <span class="o">|</span><span class="n">micropost</span><span class="o">|</span>
<span class="n">expect</span><span class="p">(</span><span class="no">Micropost</span><span class="o">.</span><span class="n">where</span><span class="p">(</span><span class="nb">id</span><span class="p">:</span> <span class="n">micropost</span><span class="o">.</span><span class="n">id</span><span class="p">))</span><span class="o">.</span><span class="n">to</span> <span class="n">be_empty</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>The application code to get <a class="ref" href="user-microposts.html#code-micropost_dependency_test">Listing 10.12</a> to pass is less than one line; in fact, it’s just an option to the <code>has_many</code> association method, as shown in <a class="ref" href="user-microposts.html#code-micropost_dependency">Listing 10.13</a>.</p>
<div class="label" id="code-micropost_dependency"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.13.</span> <span class="description">Ensuring that a user’s microposts are destroyed along with the user. <br /> <code>app/models/user.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="k">class</span> <span class="nc">User</span> <span class="o"><</span> <span class="ss">ActiveRecord::Base</span>
<span class="n">has_many</span> <span class="ss">:microposts</span><span class="p">,</span> <span class="ss">dependent:</span> <span class="ss">:destroy</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>Here the option <code>dependent: :destroy</code> in</p>
<div class="code"><div class="highlight"><pre><span class="n">has_many</span> <span class="ss">:microposts</span><span class="p">,</span> <span class="ss">dependent:</span> <span class="ss">:destroy</span>
</pre></div>
</div>
<p>arranges for the dependent microposts (i.e., the ones belonging to the given user) to be destroyed when the user itself is destroyed. This prevents userless microposts from being stranded in the database when admins choose to remove users from the system.</p>
<p>With that, the final form of the user/micropost association is in place, and all the tests should be passing:</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> bundle <span class="nb">exec </span>rspec spec/
</pre></div>
</div>
<div class="label" id="sec-micropost_validations"></div>
<h3><a id="sec-10_1_5" href="user-microposts.html#sec-micropost_validations" class="heading"><span class="number">10.1.5</span> Content validations</a></h3>
<p>Before leaving the Micropost model, we’ll add validations for the micropost <code>content</code> (following the example from <a class="ref" href="a-demo-app.html#sec-putting_the_micro_in_microposts">Section 2.3.2</a>). Like the <code>user_id</code>, the <code>content</code> attribute must be present, and it is further constrained to be no longer than 140 characters, making it an honest <em>micro</em>post. The tests generally follow the examples from the User model validation tests in <a class="ref" href="modeling-users.html#sec-user_validations">Section 6.2</a>, as shown in <a class="ref" href="user-microposts.html#code-micropost_validations_tests">Listing 10.14</a>.</p>
<div class="label" id="code-micropost_validations_tests"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.14.</span> <span class="description">Tests for the Micropost model validations. <br /> <code>spec/models/micropost_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="no">Micropost</span> <span class="k">do</span>
<span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span> <span class="o">=</span> <span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">build</span><span class="p">(</span><span class="ss">content:</span> <span class="s2">"Lorem ipsum"</span><span class="p">)</span> <span class="p">}</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="n">describe</span> <span class="s2">"when user_id is not present"</span> <span class="k">do</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span><span class="o">.</span><span class="n">user_id</span> <span class="o">=</span> <span class="kp">nil</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should_not</span> <span class="n">be_valid</span> <span class="p">}</span>
<span class="k">end</span>
<span class="n">describe</span> <span class="s2">"with blank content"</span> <span class="k">do</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span><span class="o">.</span><span class="n">content</span> <span class="o">=</span> <span class="s2">" "</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should_not</span> <span class="n">be_valid</span> <span class="p">}</span>
<span class="k">end</span>
<span class="n">describe</span> <span class="s2">"with content that is too long"</span> <span class="k">do</span>
<span class="n">before</span> <span class="p">{</span> <span class="vi">@micropost</span><span class="o">.</span><span class="n">content</span> <span class="o">=</span> <span class="s2">"a"</span> <span class="o">*</span> <span class="mi">141</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should_not</span> <span class="n">be_valid</span> <span class="p">}</span>
<span class="k">end</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>As in <a class="ref" href="modeling-users.html#sec-user_validations">Section 6.2</a>, the code in <a class="ref" href="user-microposts.html#code-micropost_validations_tests">Listing 10.14</a> uses string multiplication to test the micropost length validation:</p>
<div class="code"><div class="highlight"><pre><span class="gp">$</span> rails console
<span class="gp">></span>> <span class="s2">"a"</span> * 10
<span class="go">=> "aaaaaaaaaa"</span>
<span class="gp">></span>> <span class="s2">"a"</span> * 141
<span class="go">=> "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa</span>
<span class="go">aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"</span>
</pre></div>
</div>
<p>The application code is a one-liner:</p>
<div class="code"><div class="highlight"><pre><span class="n">validates</span> <span class="ss">:content</span><span class="p">,</span> <span class="ss">presence:</span> <span class="kp">true</span><span class="p">,</span> <span class="ss">length:</span> <span class="p">{</span> <span class="ss">maximum:</span> <span class="mi">140</span> <span class="p">}</span>
</pre></div>
</div>
<p>The resulting Micropost model is shown in <a class="ref" href="user-microposts.html#code-micropost_validations">Listing 10.15</a>.</p>
<div class="label" id="code-micropost_validations"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.15.</span> <span class="description">The Micropost model validations. <br /> <code>app/models/micropost.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="k">class</span> <span class="nc">Micropost</span> <span class="o"><</span> <span class="ss">ActiveRecord::Base</span>
<span class="n">belongs_to</span> <span class="ss">:user</span>
<span class="n">default_scope</span> <span class="o">-></span> <span class="p">{</span> <span class="n">order</span><span class="p">(</span><span class="s1">'created_at DESC'</span><span class="p">)</span> <span class="p">}</span>
<span class="n">validates</span> <span class="ss">:content</span><span class="p">,</span> <span class="ss">presence:</span> <span class="kp">true</span><span class="p">,</span> <span class="ss">length:</span> <span class="p">{</span> <span class="ss">maximum:</span> <span class="mi">140</span> <span class="p">}</span>
<span class="n">validates</span> <span class="ss">:user_id</span><span class="p">,</span> <span class="ss">presence:</span> <span class="kp">true</span>
<span class="k">end</span>
</pre></div>
</div></div>
<div class="label" id="sec-showing_microposts"></div>
<h2><a id="sec-10_2" href="user-microposts.html#sec-showing_microposts" class="heading"><span class="number">10.2</span> Showing microposts</a></h2>
<p>Although we don’t yet have a way to create microposts through the web—that comes in <a class="ref" href="user-microposts.html#sec-creating_microposts">Section 10.3.2</a>—that won’t stop us from displaying them (and testing that display). Following Twitter’s lead, we’ll plan to display a user’s microposts not on a separate microposts <code>index</code> page, but rather directly on the user <code>show</code> page itself, as mocked up in <a class="ref" href="user-microposts.html#fig-user_microposts_mockup">Figure 10.4</a>. We’ll start with fairly simple ERb templates for adding a micropost display to the user profile, and then we’ll add microposts to the sample data populator from <a class="ref" href="updating-showing-and-deleting-users.html#sec-sample_users">Section 9.3.2</a> so that we have something to display.</p>
<div class="label" id="fig-user_microposts_mockup"></div>
<div class="figure"><div class="center"><span class="graphic"><img src="images/figures/user_microposts_mockup_bootstrap.png" alt="user_microposts_mockup_bootstrap" /></span></div><div class="caption"><span class="header">Figure 10.4: </span><span class="description">A mockup of a profile page with microposts. <a href="http://railstutorial.org/images/figures/user_microposts_mockup_bootstrap-full.png">(full size)</a></span></div></div>
<p>As with the discussion of the signin machinery in <a class="ref" href="sign-in-sign-out.html#sec-remember_me">Section 8.2.1</a>, <a class="ref" href="user-microposts.html#sec-augmenting_the_user_show_page">Section 10.2.1</a> will often push several elements onto the <a href="http://en.wikipedia.org/wiki/Stack_(data_structure)">stack</a> at a time, and then pop them off one by one. If you start getting bogged down, be patient; there’s some nice payoff in <a class="ref" href="user-microposts.html#sec-sample_microposts">Section 10.2.2</a>.</p>
<div class="label" id="sec-augmenting_the_user_show_page"></div>
<h3><a id="sec-10_2_1" href="user-microposts.html#sec-augmenting_the_user_show_page" class="heading"><span class="number">10.2.1</span> Augmenting the user show page</a></h3>
<p>We begin with tests for displaying the user’s microposts, which we’ll create in the request spec for Users. Our strategy is to create a couple of factory microposts associated with the user, and then verify that the show page contains each post’s content. We’ll also verify that, as in <a class="ref" href="user-microposts.html#fig-user_microposts_mockup">Figure 10.4</a>, the total number of microposts also gets displayed.</p>
<p>We can create the posts with the <code>let</code> method, but as in <a class="ref" href="user-microposts.html#code-micropost_ordering_test">Listing 10.10</a> we want the association to exist immediately so that the posts appear on the user show page. To accomplish this, we use the <code>let!</code> variant:</p>
<div class="code"><div class="highlight"><pre><span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:m1</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="n">user</span><span class="p">,</span> <span class="ss">content:</span> <span class="s2">"Foo"</span><span class="p">)</span> <span class="p">}</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:m2</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="n">user</span><span class="p">,</span> <span class="ss">content:</span> <span class="s2">"Bar"</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="p">{</span> <span class="n">visit</span> <span class="n">user_path</span><span class="p">(</span><span class="n">user</span><span class="p">)</span> <span class="p">}</span>
</pre></div>
</div>
<p>With the microposts so defined, we can test for their appearance on the profile page using the code in <a class="ref" href="user-microposts.html#code-user_show_microposts_test">Listing 10.16</a>.</p>
<div class="label" id="code-user_show_microposts_test"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.16.</span> <span class="description">A test for showing microposts on the user <code>show</code> page. <br /> <code>spec/requests/user_pages_spec.rb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="nb">require</span> <span class="s1">'spec_helper'</span>
<span class="n">describe</span> <span class="s2">"User pages"</span> <span class="k">do</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="n">describe</span> <span class="s2">"profile page"</span> <span class="k">do</span>
<span class="n">let</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:m1</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="n">user</span><span class="p">,</span> <span class="ss">content:</span> <span class="s2">"Foo"</span><span class="p">)</span> <span class="p">}</span>
<span class="n">let!</span><span class="p">(</span><span class="ss">:m2</span><span class="p">)</span> <span class="p">{</span> <span class="no">FactoryGirl</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="ss">:micropost</span><span class="p">,</span> <span class="ss">user:</span> <span class="n">user</span><span class="p">,</span> <span class="ss">content:</span> <span class="s2">"Bar"</span><span class="p">)</span> <span class="p">}</span>
<span class="n">before</span> <span class="p">{</span> <span class="n">visit</span> <span class="n">user_path</span><span class="p">(</span><span class="n">user</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">have_content</span><span class="p">(</span><span class="n">user</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">have_title</span><span class="p">(</span><span class="n">user</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="p">}</span>
<span class="n">describe</span> <span class="s2">"microposts"</span> <span class="k">do</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">have_content</span><span class="p">(</span><span class="n">m1</span><span class="o">.</span><span class="n">content</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">have_content</span><span class="p">(</span><span class="n">m2</span><span class="o">.</span><span class="n">content</span><span class="p">)</span> <span class="p">}</span>
<span class="n">it</span> <span class="p">{</span> <span class="n">should</span> <span class="n">have_content</span><span class="p">(</span><span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">count</span><span class="p">)</span> <span class="p">}</span>
<span class="k">end</span>
<span class="k">end</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="o">.</span>
<span class="k">end</span>
</pre></div>
</div></div>
<p>Note here that we can use the <code>count</code> method <em>through</em> the association:</p>
<div class="code"><div class="highlight"><pre><span class="n">user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">count</span>
</pre></div>
</div>
<p>The association <code>count</code> method is smart, and performs the count directly in the database. In particular, it does <em>not</em> pull all the microposts out of the database and then call <code>length</code> on the resulting array, as this could become inefficient as the number of microposts grew. Instead, it asks the database to count the microposts with the given <code>user_id</code>. In the unlikely event that finding the count is still a bottleneck in your application, you can make it even faster with a <a href="http://railscasts.com/episodes/23-counter-cache-column"><em>counter cache</em></a>.</p>
<p>Although the tests in <a class="ref" href="user-microposts.html#code-user_show_microposts_test">Listing 10.16</a> won’t pass until <a class="ref" href="user-microposts.html#code-micropost_partial">Listing 10.18</a>, we’ll get started on the application code by inserting a list of microposts into the user profile page, as shown in <a class="ref" href="user-microposts.html#code-user_show_microposts">Listing 10.17</a>.</p>
<div class="label" id="code-user_show_microposts"></div>
<div class="codelisting">
<div class="listing"><span class="header">Listing 10.17.</span> <span class="description">Adding microposts to the user <code>show</code> page. <br /> <code>app/views/users/show.html.erb</code></span> </div>
<div class="code"><div class="highlight"><pre><span class="cp"><%</span> <span class="n">provide</span><span class="p">(</span><span class="ss">:title</span><span class="p">,</span> <span class="vi">@user</span><span class="o">.</span><span class="n">name</span><span class="p">)</span> <span class="cp">%></span>
<span class="nt"><div</span> <span class="na">class=</span><span class="s">"row"</span><span class="nt">></span>
.
.
.
<span class="nt"><aside></span>
.
.
.
<span class="nt"></aside></span>
<span class="nt"><div</span> <span class="na">class=</span><span class="s">"span8"</span><span class="nt">></span>
<span class="cp"><%</span> <span class="k">if</span> <span class="vi">@user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">any?</span> <span class="cp">%></span>
<span class="nt"><h3></span>Microposts (<span class="cp"><%=</span> <span class="vi">@user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">count</span> <span class="cp">%></span>)<span class="nt"></h3></span>
<span class="nt"><ol</span> <span class="na">class=</span><span class="s">"microposts"</span><span class="nt">></span>
<span class="cp"><%=</span> <span class="n">render</span> <span class="vi">@microposts</span> <span class="cp">%></span>
<span class="nt"></ol></span>
<span class="cp"><%=</span> <span class="n">will_paginate</span> <span class="vi">@microposts</span> <span class="cp">%></span>
<span class="cp"><%</span> <span class="k">end</span> <span class="cp">%></span>
<span class="nt"></div></span>
<span class="nt"></div></span>
</pre></div>
</div></div>
<p>We’ll deal with the microposts list momentarily, but there are several other things to note first. In <a class="ref" href="user-microposts.html#code-user_show_microposts">Listing 10.17</a>, the use of <code>if @user.microposts.any?</code> (a construction we saw before in <a class="ref" href="sign-up.html#code-errors_partial">Listing 7.24</a>) makes sure that an empty list won’t be displayed when the user has no microposts.</p>
<p>Also note from <a class="ref" href="user-microposts.html#code-user_show_microposts">Listing 10.17</a> that we’ve preemptively added pagination for microposts through</p>
<div class="code"><div class="highlight"><pre><span class="cp"><%=</span> <span class="n">will_paginate</span> <span class="vi">@microposts</span> <span class="cp">%></span>
</pre></div>
</div>
<p>If you compare this with the analogous line on the user index page, <a class="ref" href="updating-showing-and-deleting-users.html#code-will_paginate_index_view">Listing 9.33</a>, you’ll see that before we had just</p>
<div class="code"><div class="highlight"><pre><span class="cp"><%=</span> <span class="n">will_paginate</span> <span class="cp">%></span>
</pre></div>
</div>
<p>This worked because, in the context of the Users controller, <code>will_paginate</code> <em>assumes</em> the existence of an instance variable called <code>@users</code> (which, as we saw in <a class="ref" href="updating-showing-and-deleting-users.html#sec-pagination">Section 9.3.3</a>, should be of class <code>ActiveRecord::Relation</code>). In the present case, since we are still in the Users controller but want to paginate <em>microposts</em> instead, we pass an explicit <code>@microposts</code> variable to <code>will_paginate</code>. Of course, this means that we will have to define such a variable in the user <code>show</code> action (<a class="ref" href="user-microposts.html#code-user_show_microposts_instance">Listing 10.19</a>).</p>
<p>Finally, note that we have taken this opportunity to add a count of the current number of microposts:</p>
<div class="code"><div class="highlight"><pre><span class="nt"><h3></span>Microposts (<span class="cp"><%=</span> <span class="vi">@user</span><span class="o">.</span><span class="n">microposts</span><span class="o">.</span><span class="n">count</span> <span class="cp">%></span>)<span class="nt"></h3></span>
</pre></div>
</div>
<p>As noted, <code>@user.microposts.count</code> is the analogue of the <code>User.count</code> method, except that it counts the microposts belonging to a given user through the user/micropost association.</p>
<p>We come finally to the micropost list itself:</p>
<div class="code"><div class="highlight"><pre><span class="nt"><ol</span> <span class="na">class=</span><span class="s">"microposts"</span><span class="nt">></span>
<span class="cp"><%=</span> <span class="n">render</span> <span class="vi">@microposts</span> <span class="cp">%></span>
<span class="nt"></ol></span>
</pre></div>
</div>
<p>This code, which uses the <em>ordered list</em> tag <code>ol</code>, is responsible for generating the list of microposts, but you can see that it just defers the heavy lifting to a micropost partial. We saw in <a class="ref" href="updating-showing-and-deleting-users.html#sec-partial_refactoring">Section 9.3.4</a> that the code</p>
<div class="code"><div class="highlight"><pre><span class="cp"><%=</span> <span class="n">render</span> <span class="vi">@users</span> <span class="cp">%></span>
</pre></div>
</div>
<p>automatically renders each of the users in the <code>@users</code> variable using the <code>_user.html.erb</code> partial. Similarly, the code</p>
<div class="code"><div class="highlight"><pre><span class="cp"><%=</span> <span class="n">render</span> <span class="vi">@microposts</span> <span class="cp">%></span>
</pre></div>