Course Title: Mastering Symfony: Building Enterprise-Level PHP Applications

Section Title: API Platform and GraphQL

Topic: Build a fully-featured API using API Platform with pagination, filtering, and GraphQL support.(Lab topic)

Objective: By the end of this topic, you will be able to design, build, and deploy a fully-featured API using API Platform, with support for pagination, filtering, and GraphQL queries.

Prerequisites:

• Familiarity with Symfony framework and its components
• Understanding of REST principles and API development
• Experience with Symfony controllers, serializer component, and API authentication

Introduction: API Platform is a powerful tool for building robust, scalable, and maintainable APIs in Symfony. In this topic, we will explore how to use API Platform to build a fully-featured API with support for pagination, filtering, and GraphQL queries.

Step 1: Setting up API Platform

To start building our API, we need to install API Platform using Composer:

composer require api-platform/core

Next, we need to configure API Platform by creating a config/packages/api_platform.yaml file:

api_platform:
    default_platform: 'api_platform'
    platforms:
        api_platform:
            routes:
                resource_class: 'ApiPlatform\Core\Resource\ResourceClass'
                route_prefix: '/api'

Step 2: Defining our API Entities

We need to define our API entities using the ApiPlatform\Core\Entity\Entity class:

// src/Entity/User.php

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use ApiPlatform\Core\Annotation\Filter;
use ApiPlatform\Core\Annotation\Search;
use Doctrine\ORM\Mapping as ORM;

/**
 * @ApiResource
 * @Filter("Range")
 * @Search("fulltext")
 */
class User
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string")
     */
    private $name;

    /**
     * @ORM\Column(type="string")
     */
    private $email;

    // getters and setters
}

Step 3: Creating our API Controller

We need to create an API controller that will handle our API requests:

// src/Controller/UserController.php

namespace App\Controller;

use App\Entity\User;
use ApiPlatform\Core\Controller\ApiPlatformController;
use ApiPlatform\Core\Serializer\SerializerInterface;

class UserController extends ApiPlatformController
{
    private $serializer;

    public function __construct(SerializerInterface $serializer)
    {
        $this->serializer = $serializer;
    }

    /**
     * @GET("/users", name="get_users")
     */
    public function getUsers(): Response
    {
        $users = $this->getDoctrine()->getRepository(User::class)->findAll();

        return $this->json($users, 200);
    }

    /**
     * @GET("/users/{id}", name="get_user")
     */
    public function getUser($id): Response
    {
        $user = $this->getDoctrine()->getRepository(User::class)->find($id);

        return $this->json($user, 200);
    }

    /**
     * @POST("/users", name="create_user")
     */
    public function createUser(User $user): Response
    {
        $this->getDoctrine()->getManager()->persist($user);
        $this->getDoctrine()->getManager()->flush();

        return $this->json($user, 201);
    }

    /**
     * @PUT("/users/{id}", name="update_user")
     */
    public function updateUser(User $user): Response
    {
        $this->getDoctrine()->getManager()->persist($user);
        $this->getDoctrine()->getManager()->flush();

        return $this->json($user, 200);
    }

    /**
     * @DELETE("/users/{id}", name="delete_user")
     */
    public function deleteUser($id): Response
    {
        $user = $this->getDoctrine()->getRepository(User::class)->find($id);

        if ($user) {
            $this->getDoctrine()->getManager()->remove($user);
            $this->getDoctrine()->getManager()->flush();
        }

        return $this->json(['message' => 'User deleted successfully'], 200);
    }
}

Step 4: Adding Pagination, Filtering, and GraphQL Support

To add pagination, filtering, and GraphQL support to our API, we need to use the ApiPlatform\Core\Serializer\SerializerInterface to serialize our data.

First, we need to add pagination support:

// src/Controller/UserController.php

use ApiPlatform\Core\Serializer\SerializerInterface;

class UserController extends ApiPlatformController
{
    private $serializer;

    public function __construct(SerializerInterface $serializer)
    {
        $this->serializer = $serializer;
    }

    /**
     * @GET("/users", name="get_users")
     */
    public function getUsers(int $page = 1, int $limit = 10): Response
    {
        $users = $this->getDoctrine()->getRepository(User::class)->paginate($page, $limit);

        return $this->json($users, 200);
    }

    /**
     * @GET("/users/{id}", name="get_user")
     */
    public function getUser($id): Response
    {
        $user = $this->getDoctrine()->getRepository(User::class)->find($id);

        return $this->json($user, 200);
    }

    /**
     * @POST("/users", name="create_user")
     */
    public function createUser(User $user): Response
    {
        $this->getDoctrine()->getManager()->persist($user);
        $this->getDoctrine()->getManager()->flush();

        return $this->json($user, 201);
    }

    /**
     * @PUT("/users/{id}", name="update_user")
     */
    public function updateUser(User $user): Response
    {
        $this->getDoctrine()->getManager()->persist($user);
        $this->getDoctrine()->getManager()->flush();

        return $this->json($user, 200);
    }

    /**
     * @DELETE("/users/{id}", name="delete_user")
     */
    public function deleteUser($id): Response
    {
        $user = $this->getDoctrine()->getRepository(User::class)->find($id);

        if ($user) {
            $this->getDoctrine()->getManager()->remove($user);
            $this->getDoctrine()->getManager()->flush();
        }

        return $this->json(['message' => 'User deleted successfully'], 200);
    }
}

Next, we need to add filtering support:

// src/Controller/UserController.php

use ApiPlatform\Core\Serializer\SerializerInterface;

class UserController extends ApiPlatformController
{
    private $serializer;

    public function __construct(SerializerInterface $serializer)
    {
        $this->serializer = $serializer;
    }

    /**
     * @GET("/users", name="get_users")
     */
    public function getUsers(int $page = 1, int $limit = 10, string $filter = null): Response
    {
        $users = $this->getDoctrine()->getRepository(User::class)->paginate($page, $limit);

        if ($filter) {
            $users = $users->filterBy($filter);
        }

        return $this->json($users, 200);
    }

    /**
     * @GET("/users/{id}", name="get_user")
     */
    public function getUser($id): Response
    {
        $user = $this->getDoctrine()->getRepository(User::class)->find($id);

        return $this->json($user, 200);
    }

    /**
     * @POST("/users", name="create_user")
     */
    public function createUser(User $user): Response
    {
        $this->getDoctrine()->getManager()->persist($user);
        $this->getDoctrine()->getManager()->flush();

        return $this->json($user, 201);
    }

    /**
     * @PUT("/users/{id}", name="update_user")
     */
    public function updateUser(User $user): Response
    {
        $this->getDoctrine()->getManager()->persist($user);
        $this->getDoctrine()->getManager()->flush();

        return $this->json($user, 200);
    }

    /**
     * @DELETE("/users/{id}", name="delete_user")
     */
    public function deleteUser($id): Response
    {
        $user = $this->getDoctrine()->getRepository(User::class)->find($id);

        if ($user) {
            $this->getDoctrine()->getManager()->remove($user);
            $this->getDoctrine()->getManager()->flush();
        }

        return $this->json(['message' => 'User deleted successfully'], 200);
    }
}

Finally, we need to add GraphQL support: ```php // src/Controller/UserController.php

use ApiPlatform\Core\Serializer\SerializerInterface; use GraphQL\Type\Definition\Type; use GraphQL\Type\Definition\ObjectType; use GraphQL\Type\Definition\Field; use GraphQL\Type\Definition\InputObjectType;

class UserController extends ApiPlatformController { private $serializer;

public function __construct(SerializerInterface $serializer)
{
    $this->serializer = $serializer;
}

/**
 * @GET("/graphql", name="graphql")
 */
public function getGraphQL(): Response
{
    $schema = new GraphQLSchema([
        'query' => new ObjectType([
            'name' => 'User',
            'fields' => [
                new Field('id', Type::int()),
                new Field('name', Type::string()),
                new Field('email', Type::string()),
            ],
        ]),
        'mutation' => new ObjectType([
            'name' => 'User',
            'fields' => [
                new Field