[php] Codeigniter 使用 mysqli 無法備份資料庫

在官方的說明文件裡面已經提到，若 driver 是 mysqli ($db[‘default’][‘dbdriver’] = ‘mysqli’)，將無法使用備份的功能 $backup =& $this->dbutil->backup() ，還好有網友提供修正了(https://github.com/ci-bonfire/Bonfire/issues/1088)，只要將下列語法取代原本的函數即可。

 /**
    * MySQLi Export
    *
    * @access private
    * @param array Preferences
    * @return mixed
    */
    function _backup($params = array())
    {
        /*
        // Currently unsupported
        return $this->db->display_error('db_unsuported_feature');
        */
        if (count($params) == 0) {
            return FALSE;
        }

        // Extract the prefs for simplicity
        extract($params);

        // Build the output
        $output = '';
        foreach ((array)$tables as $table) {
            // Is the table in the "ignore" list?
            if (in_array($table, (array)$ignore, TRUE)) {
                continue;
            }

            // Get the table schema
            $query = $this->db->query("SHOW CREATE TABLE ".$this->db->database.'.'.$table.'');

            // No result means the table name was invalid
            if ($query === FALSE) {
                continue;
            }

            // Write out the table schema
            $output .= '#'.$newline.'# TABLE STRUCTURE FOR: '.$table.$newline.'#'.$newline.$newline;
            if ($add_drop == TRUE) {
                $output .= 'DROP TABLE IF EXISTS '.$table.';'.$newline.$newline;
            }

            $i = 0;
            $result = $query->result_array();
            foreach ($result[0] as $val) {
                if ($i++ % 2) {
                    $output .= $val.';'.$newline.$newline;
                }
            }

            // If inserts are not needed we're done...
            if ($add_insert == FALSE) {
                continue;
            }

            // Grab all the data from the current table
            $query = $this->db->query("SELECT * FROM $table");
            if ($query->num_rows() == 0) {
                continue;
            }

            // Fetch the field names.
            // We are going to surround all values with single quotes
            // and hope that mysql would be able to make type conversion...
            $field_str = '';
            foreach ($query->row() as $field_name => $field_value) {
                $field_str .= ''.$field_name.', ';
            }

            // Trim off the end comma
            $field_str = preg_replace( "/, $/" , "" , $field_str);

            // Build the insert string
            foreach ($query->result_array() as $row) {
                $val_str = '';
                $i = 0;
                foreach ($row as $v) {
                    // Is the value NULL?
                    if ($v === NULL) {
                        $val_str .= 'NULL';
                    } else {
                        $val_str .= $this->db->escape($v);
                    }

                    // Append a comma
                    $val_str .= ', ';
                    $i++;
                }

                // Remove the comma at the end of the string
                $val_str = preg_replace( "/, $/" , "" , $val_str);

                // Build the INSERT string
                $output .= 'INSERT INTO '.$table.' ('.$field_str.') VALUES ('.$val_str.');'.$newline;
            }
            $output .= $newline.$newline;
        }
        return $output;
    }