public function rules()
{
return ['name' => 'required|max:40|unique:classrooms', 'teacher_id' => 'required|integer|exists:teachers,id,deleted_at,NULL', 'schedule_id' => 'required|integer|exists:schedules,id', 'matters.*.id' => 'integer|exists:matters,id', 'students.*.id' => 'integer|exists:students,id'];
}