**Course Title:** Modern PHP Development: Best Practices and Advanced Techniques **Section Title:** PHP Frameworks: Introduction to Laravel or Symfony **Topic:** Database migrations and Eloquent ORM (for Laravel) or Doctrine ORM (for Symfony) In this topic, we will explore the concept of database migrations and Object-Relational Mapping (ORM) in modern PHP development, using the popular frameworks Laravel and Symfony. We will discuss the importance of database migrations, how to use Eloquent ORM in Laravel, and Doctrine ORM in Symfony. **Introduction to Database Migrations** Database migrations are a way to manage changes to your database schema over time. They allow you to define the structure of your database in code, making it easier to modify and track changes. In modern PHP development, database migrations are an essential tool for managing complex database schema. In Laravel, database migrations are handled using the Artisan CLI tool. You can create a new migration by running the following command: ``` php artisan make:migration create_users_table ``` This will create a new migration file in the `database/migrations` directory. In Symfony, database migrations are handled using the Doctrine Migrations Bundle. You can create a new migration by running the following command: ``` php bin/console doctrine:migrations:generate ``` This will create a new migration file in the `src/Migrations` directory. **Database Migrations in Laravel** In Laravel, database migrations are defined in the `database/migrations` directory. Each migration file contains two methods: `up` and `down`. The `up` method is called when the migration is applied, and the `down` method is called when the migration is rolled back. Here is an example of a migration file in Laravel: ```php // database/migrations/2022_01_01_000000_create_users_table.php use Illuminate\Database\Migrations\Migration; use Illuminate\Database\Schema\Blueprint; class CreateUsersTable extends Migration { public function up() { Schema::create('users', function (Blueprint $table) { $table->id(); $table->string('name'); $table->string('email')->unique(); $table->timestamps(); }); } public function down() { Schema::dropIfExists('users'); } } ``` **Database Migrations in Symfony** In Symfony, database migrations are defined in the `src/Migrations` directory. Each migration file contains a single method: `up`. The `up` method is called when the migration is applied. Here is an example of a migration file in Symfony: ```php // src/Migrations/Version20220101123456.php namespace App\Migrations; use Doctrine\DBAL\Schema\Schema; use Doctrine\Migrations\AbstractMigration; class Version20220101123456 extends AbstractMigration { public function up(Schema $schema) { $table = $schema->createTable('users'); $table->addColumn('id', 'integer', ['autoincrement' => true]); $table->addColumn('name', 'string', ['length' => 255]); $table->addColumn('email', 'string', ['length' => 255, 'unique' => true]); $table->addColumn('created_at', 'datetime'); $table->addColumn('updated_at', 'datetime'); } } ``` **Introduction to Eloquent ORM (Laravel)** Eloquent is the ORM provided by Laravel. It allows you to interact with your database using objects, rather than raw SQL queries. Eloquent provides a simple and elegant way to work with your database, hiding the complexity of the underlying SQL queries. Here is an example of using Eloquent to retrieve a user from the database: ```php // app/Models/User.php namespace App\Models; use Illuminate\Database\Eloquent\Model; class User extends Model { protected $fillable = ['name', 'email']; } // Usage $user = User::find(1); echo $user->name; // Output: John Doe ``` **Introduction to Doctrine ORM (Symfony)** Doctrine is the ORM provided by Symfony. It allows you to interact with your database using objects, rather than raw SQL queries. Doctrine provides a powerful and flexible way to work with your database, hiding the complexity of the underlying SQL queries. Here is an example of using Doctrine to retrieve a user from the database: ```php // src/Entity/User.php namespace App\Entity; use Doctrine\ORM\Mapping as ORM; /** * @ORM\Entity * @ORM\Table(name="users") */ class User { /** * @ORM\Id * @ORM\GeneratedValue * @ORM\Column(type="integer") */ private $id; /** * @ORM\Column(type="string", length=255) */ private $name; // ... } // Usage $userRepository = $entityManager->getRepository(User::class); $user = $userRepository->find(1); echo $user->getName(); // Output: John Doe ``` **Conclusion** In this topic, we have covered the concept of database migrations and Object-Relational Mapping (ORM) in modern PHP development, using the popular frameworks Laravel and Symfony. We have seen how to define database migrations in code, and how to use Eloquent and Doctrine to interact with your database using objects. We have also seen the differences between Laravel and Symfony, and how each framework provides its own unique approach to database migrations and ORM. We hope this topic has provided you with a solid understanding of database migrations and ORM in modern PHP development. As with all topics in this course, we encourage you to ask questions and share your experiences in the comments section below. **Resources** * Laravel Documentation: [Migrations](https://laravel.com/docs/8.x/migrations) * Symfony Documentation: [Doctrine Migrations](https://symfony.com/doc/current/doctrine/migrations.html) * Eloquent Documentation: [Eloquent](https://laravel.com/docs/8.x/eloquent) * Doctrine Documentation: [Doctrine](https://www.doctrine-project.org/projects/doctrine-orm/en/latest/index.html) **What's Next?** In the next topic, we will cover the importance of testing in modern PHP development. We will discuss the different types of tests, and how to write effective tests for your PHP applications. **Leave a Comment or Ask for Help** If you have any questions or need help with the material covered in this topic, please leave a comment below. We will do our best to respond to your questions and provide further clarification on the topics covered.