Query builder with with() to retrieve relationships

Hello,

I try for hours to understand why the $trainingId is not filtering the courses.

public function listByTraining($trainingId)
{
	$trainingId = 8; // I even added this here to verify
    $courses = Course::
        with(['teachingUnitSubject' => function($query) use($trainingId) {
            $query
                ->with(['teachingUnit' => function($query) use($trainingId) {
                    $query->with(['training' => function($query) use($trainingId) {
                        $query
                            ->where('id', $trainingId)
                            ->where('society_id', auth()->user()->society_id);
                    }]);
                }])
                ->with('subject');
        }])
        ->orderBy('start_date')->get();
    return $courses;
}

I always retrieve all the courses without filtering by trainingId.

What's wrong with my code ?

Would it be perhaps better to add a training_id field to the teaching_unit_subjects table ?

Thanks for your help ;).

V