yii\data\BaseDataProvider::getKeys PHP Method

Returns the key values associated with the data models.

public getKeys ( ) : array
return	array	the list of key values corresponding to [[models]]. Each data model in [[models]] is uniquely identified by the corresponding key value in this array.

    public function getKeys()
    {
        $this->prepare();
        return $this->_keys;
    }

BaseDataProvider