# Source: https://neon.com/llms/guides-laravel-migrations.txt

# Schema migration with Neon Postgres and Laravel

> The document guides users on performing schema migrations using Neon Postgres with Laravel, detailing the setup and execution of database migrations within the Laravel framework in the context of Neon's cloud-based PostgreSQL service.

## Source

- [Schema migration with Neon Postgres and Laravel HTML](https://neon.com/docs/guides/laravel-migrations): The original HTML version of this documentation

[Laravel](https://laravel.com/) is a popular PHP web application framework that provides an expressive and elegant syntax for building web applications. It includes an ORM (Object-Relational Mapping) called Eloquent, which allows you to interact with databases using a fluent API. Laravel also provides a powerful migration system to manage database schema changes over time.

This guide demonstrates how to use Laravel with the Neon Postgres database. We'll create a simple Laravel application and walk through the process of setting up the database, defining models, and generating and running migrations to manage schema changes.

## Prerequisites

To follow along with this guide, you will need:

- A Neon account. If you do not have one, sign up at [Neon](https://neon.tech). Your Neon project comes with a ready-to-use Postgres database named `neondb`. We'll use this database in the following examples.
- [PHP](https://www.php.net/) installed on your local machine. This guide uses PHP 8.1, but you can use any recent version compatible with Laravel.
- [Composer](https://getcomposer.org/) installed on your local machine for managing PHP dependencies.

## Setting up your Neon database

### Initialize a new project

1. Log in to the Neon Console and navigate to the [Projects](https://console.neon.tech/app/projects) section.
2. Select a project or click the **New Project** button to create a new one.

### Retrieve your Neon database connection string

Find your database connection string by clicking the **Connect** button on your **Project Dashboard** to open the **Connect to your database** modal. It should look similar to this:

```bash
postgresql://alex:AbC123dEf@ep-cool-darkness-123456.us-east-2.aws.neon.tech/dbname?sslmode=require&channel_binding=require
```

   **Important** Always use a direction connection for migrations: Neon supports both direct and pooled database connection strings, which you can find by clicking the **Connect** button on your **Project Dashboard** to open the **Connect to your database** modal. A pooled connection string connects your application to the database via a PgBouncer connection pool, allowing for a higher number of concurrent connections. However, using a pooled connection string for migrations can be prone to errors. For this reason, we recommend using a direct (non-pooled) connection when performing migrations. For more information about direct and pooled connections, see [Connection pooling](https://neon.com/docs/connect/connection-pooling).

Keep your connection string handy for later use.

## Setting up the Laravel project

### Create a new Laravel project

Open your terminal and navigate to the directory where you want to create your Laravel project. Run the following command to create a new Laravel project:

```bash
composer create-project --prefer-dist laravel/laravel guide-neon-laravel
```

This command creates a new Laravel project named `guide-neon-laravel` in the current directory.

### Set up the Database configuration

Open the `.env` file in the project root directory and update the following database connection variables:

```bash
DB_CONNECTION=pgsql
DB_PORT=5432
DATABASE_URL=NEON_POSTGRES_CONNECTION_STRING
```

Replace `NEON_POSTGRES_CONNECTION_STRING` with the connection string you retrieved from the Neon Console earlier. The `DB_CONNECTION` should be set to `pgsql` to indicate that we are using a Postgres database.

## Defining data models and running migrations

### Specify the data model

Data models are defined using the `Elquent` ORM in Laravel. Our application is a simple catalog of authors and books, where each author can have multiple books. We'll create two models, `Author` and `Book`, to represent the data.

Create a new file `Author.php` in the `app/Models` directory with the following code:

```php
<?php

namespace App\Models;
use Illuminate\Database\Eloquent\Model;

class Author extends Model
{
    protected $fillable = ['name', 'bio'];
    public function books()
    {
        return $this->hasMany(Book::class);
    }
}
```

Create another file `Book.php` in the `app/Models` directory with the following code:

```php
<?php

namespace App\Models;
use Illuminate\Database\Eloquent\Model;

class Book extends Model
{
    protected $fillable = ['title', 'author_id'];
    public function author()
    {
        return $this->belongsTo(Author::class);
    }
}
```

The `Author` model represents an author with fields for name and bio. The `Book` model represents a book with fields for title and author (as a foreign key to the `Author` model). Laravel automatically creates an `id` field for each model as the primary key and manages the `created_at` and `updated_at` timestamps.

### Generate migration files

To generate migration files for creating the `authors` and `books` tables, run the following commands in the terminal:

```bash
php artisan make:migration create_authors_table
php artisan make:migration create_books_table
```

These commands generate empty migration files in the `database/migrations` directory. Unlike frameworks such as Django, Laravel does not generate the schema automatically based on the model definitions. Instead, you define the schema in the migration files.

Open the `create_authors_table` migration file and update the `up` method to define the table schema:

```php
public function up()
{
    Schema::create('authors', function (Blueprint $table) {
        $table->id();
        $table->string('name');
        $table->text('bio')->nullable();
        $table->timestamps();
    });
}
```

Similarly, open the `create_books_table` migration file and update the `up` method:

```php
public function up()
{
    Schema::create('books', function (Blueprint $table) {
        $table->id();
        $table->string('title');
        $table->unsignedBigInteger('author_id');
        $table->timestamps();

        $table->foreign('author_id')->references('id')->on('authors')->onDelete('cascade');
    });
}
```

### Apply the migration

To apply the migration and create the corresponding tables in the Neon Postgres database, run the following command:

```bash
php artisan migrate
```

This command executes the migration files and creates the `authors` and `books` tables in the database.

### Seed the database

To populate the database with some initial data, we use Laravel's database seeding feature. Open the file `DatabaseSeeder.php` in the `database/seeders` directory and replace its contents with the following code:

```php
<?php

namespace Database\Seeders;

use App\Models\Author;
use App\Models\Book;
use Illuminate\Database\Seeder;

class DatabaseSeeder extends Seeder
{
    public function run(): void
    {
        $authors = [
            [
                'name' => 'J.R.R. Tolkien',
                'bio' => 'The creator of Middle-earth and author of The Lord of the Rings.',
                'books' => [
                    ['title' => 'The Fellowship of the Ring'],
                    ['title' => 'The Two Towers'],
                    ['title' => 'The Return of the King'],
                ],
            ],
            [
                'name' => 'George R.R. Martin',
                'bio' => 'The author of the epic fantasy series A Song of Ice and Fire.',
                'books' => [
                    ['title' => 'A Game of Thrones'],
                    ['title' => 'A Clash of Kings'],
                    ['title' => 'A Storm of Swords'],
                ],
            ],
            [
                'name' => 'J.K. Rowling',
                'bio' => 'The creator of the Harry Potter series.',
                'books' => [
                    ['title' => 'Harry Potter and the Philosopher\'s Stone'],
                    ['title' => 'Harry Potter and the Chamber of Secrets'],
                ],
            ],
        ];

        foreach ($authors as $authorData) {
            $author = Author::create([
                'name' => $authorData['name'],
                'bio' => $authorData['bio'],
            ]);

            foreach ($authorData['books'] as $bookData) {
                $author->books()->create($bookData);
            }
        }
    }
}
```

This seeder creates three authors and associates them with their corresponding books. To run this script and populate the database, run the following command in the terminal:

```bash
php artisan db:seed
```

## Implement the application

### Create routes and controllers

We'll create two routes and corresponding controllers to display the authors and books in our application.

Open the `routes/web.php` file and add the following routes:

```php
...

use App\Http\Controllers\AuthorController;
use App\Http\Controllers\BookController;

...

Route::get('/authors', [AuthorController::class, 'index'])->name('authors.index');
Route::get('/books/{author}', [BookController::class, 'index'])->name('books.index');
```

We define two routes: `/authors` to list all authors and `/books/{author}` to list books by a specific author.

Now, create a new file `AuthorController.php` in the `app/Http/Controllers` directory with the following code:

```php
<?php

namespace App\Http\Controllers;

use App\Models\Author;

class AuthorController extends Controller
{
    public function index()
    {
        $authors = Author::all();
        return response()->json($authors);
    }
}
```

Similarly, create another file `BookController.php` in the `app/Http/Controllers` directory with the following code:

```php
<?php

namespace App\Http\Controllers;

use App\Models\Author;

class BookController extends Controller
{
    public function index(Author $author)
    {
        $books = $author->books;
        return response()->json($books);
    }
}
```

These controllers define the `index` action to retrieve all authors and books by a specific author, respectively. The data is returned as JSON responses.

### Run the Laravel development server

To start the Laravel development server and test the application, run the following command:

```bash
php artisan serve
```

Navigate to the url `http://localhost:8000/authors` in your browser to view the list of authors. You can also view the books by a specific author by visiting `http://localhost:8000/books/{author_id}`.

## Applying schema changes

We will demonstrate how to handle schema changes by adding a new field `country` to the `Author` model, which will store the author's country of origin.

### Update the data model

Open the `Author.php` file in the `app/Models` directory and add the `country` field to the `$fillable` property:

```php
protected $fillable = ['name', 'bio', 'country'];
```

### Generate and run the migration

To generate a new migration file for the schema change, run the following command:

```bash
php artisan make:migration add_country_to_authors_table
```

This command generates a new migration file in the `database/migrations` directory.

Open the generated migration file and update the `up` method to add the new `country` column:

```php
public function up()
{
    Schema::table('authors', function (Blueprint $table) {
        $table->string('country')->nullable()->after('bio');
    });
}
```

Now, to apply the migration, run the following command:

```bash
php artisan migrate
```

### Test the schema change

Restart the Laravel development server:

```bash
php artisan serve
```

Navigate to the url `http://localhost:8000/authors` to view the list of authors. Each author entry now includes the `country` field set to `null`, reflecting the schema change.

## Conclusion

In this guide, we demonstrated how to set up a Laravel project with `Neon` Postgres, define database models using Eloquent, generate migrations, and run them. Laravel's Eloquent ORM and migration system make it easy to interact with the database and manage schema evolution over time.

## Source code

You can find the source code for the application described in this guide on GitHub.

- [Migrations with Neon and Laravel](https://github.com/neondatabase/guide-neon-laravel): Run Neon database migrations in a Laravel project

## Resources

For more information on the tools and concepts used in this guide, refer to the following resources:

- [Laravel Documentation](https://laravel.com/docs)
- [Neon Postgres](https://neon.com/docs/introduction)