laravel BelongsTo relationship with different databases not working

Solution for laravel v5.7 and above

class Album extends Eloquent {

   // default connection

   public function genre() {
       return $this->setConnection('Resources')->belongsTo('genre');
   }
...
}

This is the way it worked for me:

In my .env and config/database.php i have defined my other connection => How to use multiple databases in Laravel

I updated my model this way:

class MyOtherDBModel extends Model
{
    protected $table = 'tablename';
    protected $connection = 'mysql2';

    public function __construct(array $attributes = [])
    {
        $this->table = env('DB_DATABASE_2').'.'.$this->table;
        parent::__construct($attributes);
    }
}

class MyModel extends Model
{
    public function myOtherModel()
    {
        return $this->belongsTo(MyOtherDBModel::class, 'field', 'field');
    }
}

Now i can call

$query = MyModel::whereHas('myOtherModel');