For the scenario, imagine posts has a foreign key user_id referencing users.id
public function up()
{
Schema::create('posts', function(Blueprint $table) {
$table->increments('id');
$table->string('title');
$table->text('body');
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users')->onDelete('cascade');
$table->timestamps();
});
}running seeds with truncate() will trigger a constraint violation if foreign key checks is not disabled.
Syntax error or access violation: 1701 Cannot truncate a table referenced in a foreign key constraint ...
The fix:
DatabaseSeeder.php
class DatabaseSeeder extends Seeder {
/**
* Run the database seeds.
*
* @return void
*/
public function run()
{
Eloquent::unguard();
//disable foreign key check for this connection before running seeders
DB::statement('SET FOREIGN_KEY_CHECKS=0;');
$this->call('UsersTableSeeder');
$this->call('PostsTableSeeder');
// supposed to only apply to a single connection and reset it's self
// but I like to explicitly undo what I've done for clarity
DB::statement('SET FOREIGN_KEY_CHECKS=1;');
}
}fix from here http://stackoverflow.com/questions/14666277/laravel-4-working-with-relationships-in-seeds
As pointed out in the comments at SO you wouldn't want to disable foreign key checks on a production app but you really don't want to run seed files in production either so obviously this is not intended for production but helpful in development.
Thanks.