You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: dm_open.go
    path of file: ./repos/gf/contrib/drivers/dm
    
    the code of the file until where you have to start completion: // Copyright GoFrame Author(https://goframe.org). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.

package dm

import (
	"database/sql"
	"fmt"

	"net/url"
	"strings"

	"github.com/gogf/gf/v2/database/gdb"
	"github.com/gogf/gf/v2/errors/gcode"
	"github.com/gogf/gf/v2/errors/gerror"
)

// Open creates and returns an underlying sql.DB object for pgsql.
func (d *Driver) Open(config *gdb.ConfigNode) (db *sql.DB, err error) {
	var (
		source               string
		underlyingDriverName = "dm"
	)
	if config.Name == "" {
		return nil, fmt.Errorf(
			`dm.Open failed for driver "%s" without DB Name`, underlyingDriverName,
		)
	}
	// Data Source Name of DM8:
	// dm://userName:p
    
func (d *Driver) Open(config *gdb.ConfigNode) (db *sql.DB, err error) {
	var (
		source               string
		underlyingDriverName = "dm"
	)
	if config.Name == "" {
		return nil, fmt.Errorf(
			`dm.Open failed for driver "%s" without DB Name`, underlyingDriverName,
		)
	}
	// Data Source Name of DM8:
	// dm://userName:password@ip:port/dbname
	// dm://userName:password@DW/dbname?DW=(192.168.1.1:5236,192.168.1.2:5236)
	var domain string
	if config.Port != "" {
		domain = fmt.Sprintf("%s:%s", config.Host, config.Port)
	} else {
		domain = config.Host
	}
	source = fmt.Sprintf(
		"dm://%s:%s@%s/%s?charset=%s&schema=%s",
		config.User, config.Pass, domain, config.Name, config.Charset, config.Name,
	)
	// Demo of timezone setting:
	// &loc=Asia/Shanghai
	if config.Timezone != "" {
		if strings.Contains(config.Timezone, "/") {
			config.Timezone = url.QueryEscape(config.Timezone)
		}
		source = fmt.Sprintf("%s&loc%s", source, config.Timezone)
	}
	if config.Extra != "" {
		source = fmt.Sprintf("%s&%s", source, config.Extra)
	}

	if db, err = sql.Open(underlyingDriverName, source); err != nil {
		err = gerror.WrapCodef(
			gcode.CodeDbOperationError, err,
			`dm.Open failed for driver "%s" by source "%s"`, underlyingDriverName, source,
		)
		return nil, err
	}
	return
}