public function primaryKey()
    {
        $pk = $this->meta->schema->primaryKey;
        if (is_array($pk)) {
            $ppk = [];
            foreach ($pk as $key) {
                $ppk[] = $key;
            }

            return implode('.', $ppk);
        }

        return $pk;
    }
public function primaryKey()
    {
        $pk = $this->meta->schema->primaryKey;
        if (is_array($pk)) {
            $ppk = [];
            foreach ($pk as $key) {
                $ppk[] = $key;
            }

            return implode('.', $ppk);
        }

        return $pk;
    }
public function primaryKey ( ) { $ pk = $ this -> meta -> schema -> primaryKey ; if ( is_array ( $ pk ) ) { $ ppk = [ ] ; foreach ( $ pk as $ key ) { $ ppk [ ] = $ key ; } return implode ( '.' , $ ppk ) ; } return $ pk ; }
Retrieve the primary key column for the model item.

@return string the primary key
Retrieve the primary key column for the model item .