hasOne add laravel code example
Example 1: how to use where relationship laravel
Event::with(["owner", "participants" => function($q) use($someId){
$q->where('participants.IdUser', '=', 1);
//$q->where('some other field', $someId);
}])
Example 2: laravel eloquent associate
$account = App\Account::find(10);
$user->account()->associate($account);
$user->save();
Example 3: eloquent relationships
$roles = App\User::find(1)->roles()->orderBy('name')->get();