在 null 上调用成员函数 addEagerConstraints() 在 laravel 6 上出现此错误

Question

I am using laravel 6.0 and I am getting this strange error "Call to a member function addEagerConstraints() on null" what I have is notification table where I am having notification_id and this notification_id is linked to notification_message table, I am trying to create a realtion between them I tried everything but I am getting this strange error.

Here is my notification Model where i have defined this relationship

public function notificationMessage(){
    $this->hasOne('App\Models\NotificationMessage','id');
}

Answer 1

Don't forget to return the relationship

public function notificationMessage(){
    return $this->hasOne('App\Models\NotificationMessage','id');
}