Change association behavior to return nils if records cannot be found (…

…#60)

* change association behavior to return nils if records cannot be found

* make find_by() behavior optional

CHANGELOG.MD

@@ -1,3 +1,7 @@
+## Subroutine 4.0.1
+
+Association fields can now use `find_by()` instead of `find_by!()` by passing a `raise_on_miss: false` option. This places the responsibility on the op to manage nil cases rather than handling RecordNotFound errors.
+
 ## Subroutine 4.0
 
 The `Subroutine::Fields` module now contains a class_attribute that allows the altering of param accessor behaviors. `include_defaults_in_params` is now available to opt into including the default values in usage of the `all_params (alias params)` method. Backwards compatibility is preserved by defaulting the value to `false`. If switched to true, when an input is omitted and the field is configured with a default value, it will be included in the `all_params` object.

lib/subroutine/association_fields.rb

@@ -187,7 +187,11 @@ def fetch_association_instance(config)
       scope = klass.all
       scope = scope.unscoped if config.unscoped?
 
-      scope.find_by!(config.find_by => value)
+      if config.raise_on_miss?
+        scope.find_by!(config.find_by => value)
+      else
+        scope.find_by(config.find_by => value)
+      end
     end
 
     def maybe_raise_on_association_type_mismatch!(config, record)

lib/subroutine/association_fields/configuration.rb

@@ -30,6 +30,10 @@ def polymorphic?
         !!config[:polymorphic]
       end
 
+      def raise_on_miss?
+        config[:raise_on_miss] != false
+      end
+
       def as
         config[:as] || field_name
       end

lib/subroutine/version.rb

@@ -4,8 +4,8 @@ module Subroutine
 
   MAJOR = 4
   MINOR = 0
-  PATCH = 0
-  PRE   = "alpha"
+  PATCH = 1
+  PRE   = nil
 
   VERSION = [MAJOR, MINOR, PATCH, PRE].compact.join(".")
 

test/subroutine/association_test.rb

@@ -335,5 +335,15 @@ def test_groups_are_preserved_to_association_components
       assert_equal({}, op.without_info_params)
     end
 
+    def test_find_by_is_used_if_raise_on_miss_is_false
+      all_mock = mock
+
+      ::User.expects(:all).returns(all_mock)
+      all_mock.expects(:find_by).with(id: 1).returns(nil)
+
+      op = SafeAssociationOp.new user_type: "User", user_id: 1
+      assert_nil op.user
+    end
+
   end
 end

test/support/ops.rb

@@ -27,10 +27,6 @@ def self.find_by(params)
     new(params)
   end
 
-  def self.find_by!(params)
-    find_by(params) || raise
-  end
-
   def self.type_for_attribute(attribute)
     case attribute
     when :id
@@ -342,6 +338,12 @@ class SimpleAssociationOp < ::OpWithAssociation
 
 end
 
+class SafeAssociationOp < ::OpWithAssociation
+
+  association :user, raise_on_miss: false
+
+end
+
 class SimpleAssociationWithStringIdOp < ::OpWithAssociation
 
   association :string_id_user