public function filterAndConvertToArray($columns)
    {
        $this->columns = [];
        $columns = explode(',', $columns);

        foreach ($columns as $column) {
            try {
                list($col, $val) = explode(':', $column, self::EXPLODE_MAX_LIMIT);
            } catch (\Exception $e) {
                throw new \Exception('Unable to explode columns based on ":" separator');
            }

            $val = $this->checkForKeyword(trim($val));
            $this->columns[trim($col)] = $val;
        }

        return $this;
    }