Laravel - Seeding Many-to-Many Relationship

Just for a seeder you can use something like this:

   for ($i = 0; $i < 50; $i++) {
        $user = factory(App\User::class)->create();

        $role = factory(App\Role::class)->create();

        DB::table('role_user')->insert([
            'user_id' => $user->id,
            'role_id' => $role->id
        ]);
    }

But normally you need to define relation like has many through https://laravel.com/docs/5.4/eloquent-relationships#has-many-through

Then you will be able to use:

$user->roles()->save($role);

A much cleaner method can be: after you define the factory for App\User and App\Roles you can call the afterCreating method like this:

$factory->define(App\User::class, function ...);
$factory->define(App\Role::class, function ...);

$factory->afterCreating(App\User::class, function ($row, $faker) {
    $row->roles()->attach(rand(1,20));
});

Then in Seeds you first create the roles, then the users

public function run()
{
    factory(App\Role::class, 20)->create();
    factory(App\User::class, 50)->create();
}

Now you have 50 users each of them with one role attached.

Another way is to use saveMany() function

public function run()
{

   factory(App\User::class,3)->create();

   $roles = factory(App\Role::class,3)->create();

   App\User::All()->each(function ($user) use ($roles){
      $user->roles()->saveMany($roles);
   });
}

You can use attach() or sync() method on a many-to-many relationship.

There are multiple ways you can approach this. Here one of them:

// Populate roles
factory(App\Role::class, 20)->create();

// Populate users
factory(App\User::class, 50)->create();

// Get all the roles attaching up to 3 random roles to each user
$roles = App\Role::all();

// Populate the pivot table
App\User::all()->each(function ($user) use ($roles) { 
    $user->roles()->attach(
        $roles->random(rand(1, 3))->pluck('id')->toArray()
    ); 
});