public function completeMatter($classroom_id, $matter_id)
{
$classroomMatter = ClassroomMatter::where('classroom_id', $classroom_id)->where('matter_id', $matter_id)->first();
if (is_null($classroomMatter)) {
return false;
}
$this->matterCompleteds()->attach($classroomMatter);
$student = $this->whereHas('matterCompleteds', function ($q) use($classroomMatter) {
$q->where('id', $classroomMatter->id);
})->first();
return !is_null($student);
}