Альберт Табак

$rooms = Rooms::find()->joinWith([
        'reservation' => function ($query) use ($rdRooms){
            $query->where(['rooms.id_room' => $rdRooms]);
        }

class FilmCategory {.....
public function getFilms(){
        return $this->hasMany(Films::className(), ['film_id' => 'film_id'])
            ->viaTable('films_categories', ['category_id' => 'category_id']);
    }