public function has($relation)
    {
        $query = $this->make();
        return $query->has($relation)->get( $this->getParameters );
    }
public function has($relation)
    {
        $query = $this->make();
        return $query->has($relation)->get( $this->getParameters );
    }
public function has ( $ relation ) { $ query = $ this -> make ( ) ; return $ query -> has ( $ relation ) -> get ( $ this -> getParameters ) ; }
returns all models that have a required relation

@param string $relation
@return Collection
returns all models that have a required relation