public function getColumns()
    {
        if (is_null($this->_columns)) {
            $this->columns = $this->dataProvider->model->attributeNames();
        }

        return $this->_columns;
    }
public function getColumns()
    {
        if (is_null($this->_columns)) {
            $this->columns = $this->dataProvider->model->attributeNames();
        }

        return $this->_columns;
    }
public function getColumns ( ) { if ( is_null ( $ this -> _columns ) ) { $ this -> columns = $ this -> dataProvider -> model -> attributeNames ( ) ; } return $ this -> _columns ; }
Get columns.

@return [[@doctodo return_type:getColumns]] [[@doctodo return_description:getColumns]]
Get columns .