Difference Between Factories and Seeders in Laravel

Laravel provides both factories and seeders for database population, but they serve different purposes and are used in different scenarios.

Database Factories

Purpose: Factories are used to generate model instances with fake/dummy data, primarily for testing.

Key Characteristics:

• Define how models should be generated with fake data

• Use Faker library to generate random values

• Primarily used in tests and local development

• Can create model instances without persisting to database

• Support relationships and states (variations)

Example Factory:

// database/factories/UserFactory.php
$factory->define(User::class, function (Faker $faker) {
    return [
        'name' => $faker->name,
        'email' => $faker->unique()->safeEmail,
        'password' => bcrypt('password'),
    ];
});

// Usage:
$user = factory(User::class)->create(); // Persisted to DB
$user = factory(User::class)->make();   // Not persisted

Database Seeders

Purpose: Seeders are used to populate your database with specific, predefined data.

Key Characteristics:

• Used to insert actual application data (not random/fake)

• Often used for initial application setup (admin users, categories, etc.)

• Can use factories internally to generate data

• Run manually or during deployment

• Typically contain specific, predictable data

Example Seeder:

// database/seeds/UsersTableSeeder.php
public function run()
{
    // Create specific admin user
    User::create([
        'name' => 'Admin User',
        'email' => 'admin@example.com',
        'password' => bcrypt('secret'),
        'role' => 'admin'
    ]);
    
    // Use factory to create multiple users
    factory(User::class, 50)->create();
}

Key Differences

When to Use Each

Use Factories when you need:

• Test data with random values

• Multiple variations of model data

• To quickly generate many model instances

• Data for your test cases

Use Seeders when you need:

• Initial application data (admin accounts, etc.)

• Reference data (countries, product categories)

• To set up a consistent starting database state

• Data that must be exactly the same each time

Working Together

Factories and seeders are often used together:

// In a seeder
public function run()
{
    // Create specific records
    User::create([...]);
    
    // Then use factories to generate random data
    factory(User::class, 100)->create();
}

You would then run the seeder with:

php artisan db:seed
# or for a specific seeder
php artisan db:seed --class=UsersTableSeeder