protected function _retrievePostFilter(\Mmi\Http\RequestPost $post)
    {
        //brak filtracji dla tego grida
        if (false === strpos($post->filter, $this->_grid->getClass())) {
            return;
        }
        $columnName = substr($post->filter, strpos($post->filter, '[') + 1, -1);
        $tableName = null;
        $fieldName = $columnName;
        //obsługa joinowanych
        if (strpos($columnName, '.')) {
            $fieldTable = explode('.', $columnName);
            $tableName = $fieldTable[0];
            $fieldName = $fieldTable[1];
        }
        //paginator
        if ($fieldName == '_paginator_') {
            //ustawianie filtra
            return (new GridStateFilter())
                    ->setField($fieldName)
                    ->setValue($post->value);
        }
        //iteracja po kolumnach
        foreach ($this->_grid->getColumns() as $column) {
            if ($column->getName() != $columnName) {
                continue;
            }
            //ustawianie filtra
            return (new GridStateFilter())
                    ->setField($fieldName)
                    ->setTableName($tableName)
                    ->setMethod($column->getMethod())
                    ->setValue($post->value);
        }
    }