public function getPrimaryKeyValue()
    {
        $key = $this->getPrimaryKeyName();
        return isset($this->$key) ? $this->$key : null;
    }
public function getPrimaryKeyValue()
    {
        $key = $this->getPrimaryKeyName();
        return isset($this->$key) ? $this->$key : null;
    }
public function getPrimaryKeyValue ( ) { $ key = $ this -> getPrimaryKeyName ( ) ; return isset ( $ this -> $ key ) ? $ this -> $ key : null ; }
return the model's current primary key value
this is designed to work for a single model "record" and not a collection
return the model s current primary key value this is designed to work for a single model record and not a collection