Added an example using actix-web, async_graphql and diesel

examples/web_app_graphql/.env.example.txt

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+DATABASE_URL=postgres://[username]:[password]@localhost/[database_name]
+MEILISEARCH_HOST=http://localhost:7700
+MEILISEARCH_API_KEY=[your-master-key]
+MIGRATIONS_DIR_PATH=migrations

examples/web_app_graphql/.gitignore

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+/target
+/Cargo.lock
+
+.env

examples/web_app_graphql/Cargo.toml

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+[package]
+name = "meilisearch-ex"
+version = "0.1.0"
+edition = "2021"
+authors = ["Eugene Korir <[email protected]>"]
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+actix-cors = "0.6.5"
+actix-web = "4.4.0"
+async-graphql = "6.0.11"
+async-graphql-actix-web = "6.0.11"
+diesel = { version = "2.1.4", features = ["postgres"] }
+diesel-async = { version = "0.4.1", features = ["postgres", "deadpool"] }
+diesel_migrations = "2.1.0"
+dotenvy = "0.15.7"
+env_logger = "0.10.1"
+envy = "0.4.2"
+futures = "0.3.29"
+log = "0.4.20"
+meilisearch-sdk = "0.24.3"
+serde = { version = "1.0.192", features = ["derive"] }
+serde_json = "1.0.108"
+thiserror = "1.0.51"
+validator = { version = "0.16.1", features = ["derive"] }

examples/web_app_graphql/README.md

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+# Meilisearch example with graphql using `diesel`, `async_graphql` and `postgres`
+
+## Contents
+
+Setting up a graphql server using `async_graphql` and `actix-web`
+
+Using `diesel` to query the database
+
+Using `meilisearch-sdk` to search for records that match a given criteria
+
+## Running the example
+
+The meilisearch server needs to be running. You can run it by the command below
+
+```bash
+meilisearch --master-key <your master key>
+```
+
+Then you can run the application by simply running
+
+```bash
+cargo run --release
+```
+
+The above command will display a link to your running instance and you can simply proceed by clicking the link or navigating to your browser.
+
+### Running the resolvers
+
+On your browser, you will see a graphql playground in which you can use to run some queries
+
+You can use the `searchUsers` query as follows:
+
+```gpl
+query {
+  users{
+    search(queryString: "Eugene"){
+      lastName
+      firstName
+      email
+    }
+  }
+}
+```
+
+### Errors
+
+Incase you run into the following error:
+
+```bash
+= note: ld: library not found for -lpq
+          clang: error: linker command failed with exit code 1 (use -v to see invocation)
+```
+
+Run:
+
+```bash
+sudo apt install libpq-dev
+```
+
+This should fix the error

examples/web_app_graphql/diesel.toml

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+# For documentation on how to configure this file,
+# see https://diesel.rs/guides/configuring-diesel-cli
+
+[print_schema]
+file = "src/schema.rs"
+custom_type_derives = ["diesel::query_builder::QueryId"]
+
+[migrations_directory]
+dir = "migrations"

examples/web_app_graphql/migrations/00000000000000_diesel_initial_setup/down.sql

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+-- This file was automatically created by Diesel to setup helper functions
+-- and other internal bookkeeping. This file is safe to edit, any future
+-- changes will be added to existing projects as new migrations.
+
+DROP FUNCTION IF EXISTS diesel_manage_updated_at(_tbl regclass);
+DROP FUNCTION IF EXISTS diesel_set_updated_at();

examples/web_app_graphql/migrations/00000000000000_diesel_initial_setup/up.sql

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+-- This file was automatically created by Diesel to setup helper functions
+-- and other internal bookkeeping. This file is safe to edit, any future
+-- changes will be added to existing projects as new migrations.
+
+
+
+
+-- Sets up a trigger for the given table to automatically set a column called
+-- `updated_at` whenever the row is modified (unless `updated_at` was included
+-- in the modified columns)
+--
+-- # Example
+--
+-- ```sql
+-- CREATE TABLE users (id SERIAL PRIMARY KEY, updated_at TIMESTAMP NOT NULL DEFAULT NOW());
+--
+-- SELECT diesel_manage_updated_at('users');
+-- ```
+CREATE OR REPLACE FUNCTION diesel_manage_updated_at(_tbl regclass) RETURNS VOID AS $$
+BEGIN
+    EXECUTE format('CREATE TRIGGER set_updated_at BEFORE UPDATE ON %s
+                    FOR EACH ROW EXECUTE PROCEDURE diesel_set_updated_at()', _tbl);
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION diesel_set_updated_at() RETURNS trigger AS $$
+BEGIN
+    IF (
+        NEW IS DISTINCT FROM OLD AND
+        NEW.updated_at IS NOT DISTINCT FROM OLD.updated_at
+    ) THEN
+        NEW.updated_at := current_timestamp;
+    END IF;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;

examples/web_app_graphql/migrations/2023-12-20-105441_users/down.sql

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+-- This file should undo anything in `up.sql`
+drop table if exists users;

examples/web_app_graphql/migrations/2023-12-20-105441_users/up.sql

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+-- Your SQL goes here
+create table if not exists users(
+    id serial primary key,
+    first_name varchar not null,
+    last_name varchar not null,
+    email varchar not null unique
+);

examples/web_app_graphql/src/app_env_vars.rs

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+use serde::Deserialize;
+
+//Environment variables required for the app to run
+#[derive(Deserialize, Debug, Clone)]
+pub struct AppEnvVars {
+    pub meilisearch_api_key: String,
+    pub meilisearch_host: String,
+    pub database_url: String,
+    pub migrations_dir_path: String,
+}

examples/web_app_graphql/src/errors/mod.rs

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+use diesel::ConnectionError;
+use diesel_async::pooled_connection::deadpool::{BuildError, PoolError};
+use diesel_migrations::MigrationError;
+use serde_json::Error as SerdeError;
+use thiserror::Error;
+
+#[derive(Debug, Error)]
+pub enum ApplicationError {
+    #[error("Missing environment variable")]
+    Envy(#[from] envy::Error),
+    #[error("Input/Output error")]
+    Io(#[from] std::io::Error),
+    #[error("Database error")]
+    Diesel(#[from] diesel::result::Error),
+    #[error("Deadpool build error")]
+    DeadpoolBuild(#[from] BuildError),
+    #[error("Migration error")]
+    Migration(#[from] MigrationError),
+    #[error("Connection error")]
+    DieselConnection(#[from] ConnectionError),
+    #[error("Pool Error")]
+    Pool(#[from] PoolError),
+    #[error("Serde json error")]
+    SerDe(#[from] SerdeError),
+}

examples/web_app_graphql/src/graphql_schema/mod.rs

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+use async_graphql::SimpleObject;
+pub mod users;
+
+use users::mutation::UsersMut;
+use users::query::UsersQuery;
+
+#[derive(Default, SimpleObject)]
+pub struct Query {
+    users: UsersQuery,
+}
+
+#[derive(Default, SimpleObject)]
+pub struct Mutation {
+    users: UsersMut,
+}

examples/web_app_graphql/src/graphql_schema/users/mod.rs

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+pub mod mutation;
+pub mod query;

examples/web_app_graphql/src/graphql_schema/users/mutation/add_user.rs

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+use async_graphql::{Context, InputObject, Object, Result};
+use diesel_async::RunQueryDsl;
+use validator::Validate;
+
+use crate::{
+    models::{NewUser, User},
+    validate_input, GraphQlData,
+};
+
+#[derive(Default)]
+pub struct AddUser;
+
+#[derive(InputObject, Validate)]
+pub struct IAddUser {
+    #[validate(length(min = 1))]
+    pub first_name: String,
+    #[validate(length(min = 1))]
+    pub last_name: String,
+    #[validate(email)]
+    pub email: String,
+}
+
+#[Object]
+impl AddUser {
+    ///Resolver for creating a new user and storing that data in the database
+    ///
+    /// The mutation can be run as follows
+    /// ```gpl
+    /// mutation AddUser{
+    ///     users {
+    ///         signup(input: {firstName: "",lastName: "",email: ""}){
+    ///             id
+    ///             firstName
+    ///             lastName
+    ///             email
+    ///         }
+    ///     }
+    /// }
+    pub async fn signup(&self, ctx: &Context<'_>, input: IAddUser) -> Result<User> {
+        validate_input(&input)?;
+
+        use crate::schema::users::dsl::users;
+
+        let GraphQlData { pool, .. } = ctx.data().map_err(|e| {
+            log::error!("Failed to get app data: {:?}", e);
+            e
+        })?;
+
+        let mut connection = pool.get().await?;
+
+        let value = NewUser {
+            first_name: input.first_name,
+            last_name: input.last_name,
+            email: input.email,
+        };
+
+        let result = diesel::insert_into(users)
+            .values(&value)
+            .get_result::<User>(&mut connection)
+            .await
+            .map_err(|e| {
+                log::error!("Could not create new user: {:#?}", e);
+                e
+            })?;
+
+        Ok(result)
+    }
+}

examples/web_app_graphql/src/graphql_schema/users/mutation/mod.rs

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+pub mod add_user;
+
+use add_user::AddUser;
+use async_graphql::MergedObject;
+
+//Combines user queries into one struct
+#[derive(Default, MergedObject)]
+pub struct UsersMut(pub AddUser);

examples/web_app_graphql/src/graphql_schema/users/query/get_users.rs

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+use async_graphql::{Context, Object, Result};
+use diesel_async::RunQueryDsl;
+
+use crate::{models::User, GraphQlData};
+
+#[derive(Default)]
+pub struct GetUsers;
+
+#[Object]
+impl GetUsers {
+    //Resolver for querying the database for user records
+    pub async fn get_users(&self, ctx: &Context<'_>) -> Result<Vec<User>> {
+        use crate::schema::users::dsl::users;
+
+        let GraphQlData { pool, .. } = ctx.data().map_err(|e| {
+            log::error!("Failed to get app data: {:?}", e);
+            e
+        })?;
+
+        let mut connection = pool.get().await?;
+
+        let list_users = users.load::<User>(&mut connection).await?;
+
+        Ok(list_users)
+    }
+}

examples/web_app_graphql/src/graphql_schema/users/query/mod.rs

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+pub mod get_users;
+pub mod search;
+
+use async_graphql::MergedObject;
+use get_users::GetUsers;
+use search::SearchUsers;
+
+//Combines user queries into one struct
+#[derive(Default, MergedObject)]
+pub struct UsersQuery(pub GetUsers, pub SearchUsers);