Golang与Mongo数据库

随着Mongo数据库的使用越来越多，在开发中选择Mongo也并不少见。这是Golang连接Mongo数据库的示例，介绍了开发中应如何写连接Mongo数据库，如何写单元测试，如何mock数据。

驱动包

Golang的Mongo驱动包有两个:

官方包
Mgo
本人正好都使用过这两个包，个人使用体验是官方包偏繁琐些，代码写出来偏mongo命令行风格，不支持ORM功能，所有代码量相对多些。相对而言Mgo支持ORM，写出的代码量少，可维护性好。对于性能方面没有去做过比较，就不做对比了。目前我使用mgo多些，主要考虑因素是编码效率。下面就以mgo为例来介绍

示例

导入包github.com/globalsign/mgo和github.com/globalsign/mgo/bson
连接Mongo mgo.Dial(mongoURL)
指定数据库和Collection session.DB("db name").C("collection")
插入数据 c.Insert(&db.Person{}
查找数据 c.Find(bson.M{}).One()

package main

import (
	"fmt"
	"log"

	"github.com/globalsign/mgo"
	"github.com/globalsign/mgo/bson"
	"github.com/gunsluo/go-example/mgo/db"
)

const (
	mongoURL = "mongodb://root:password@127.0.0.1:27017"
)

func main() {
	session, err := mgo.Dial(mongoURL)
	if err != nil {
		panic(err)
	}
	defer session.Close()

	// Optional. Switch the session to a monotonic behavior.
	session.SetMode(mgo.Monotonic, true)

	c := session.DB("fm").C("people")
	err = c.Insert(&db.Person{"Ale", "+55 53 8116 9639"},
		&db.Person{"Cla", "+55 53 8402 8510"})
	if err != nil {
		log.Fatal(err)
	}

	result := db.Person{}
	err = c.Find(bson.M{"name": "Ale"}).One(&result)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Phone:", result.Phone)
}

package db

type Person struct {
	Name  string
	Phone string
}

Mock

gomcok是Golang中非常好的mock数据工具，它的原理是基于interface的实现。显然目前版本的mgo不是interface的实现，所以我们需要对mgo实现interface抽象。github上有percona/pmgo项目已经实现了该功能，但它不是最新版本的mgo实现且接口不全。我fork该项目修改了问题实现了pmgo;

查询用户信息

package main

import (
	"fmt"
	"log"

	"github.com/globalsign/mgo/bson"
	"github.com/percona/pmgo"
)

// User is  a user information
type User struct {
	ID   int    `bson:"id"`
	Name string `bson:"name"`
}

func main() {
	dialer := pmgo.NewDialer()
	session, err := dialer.Dial("mongodb://root:password@localhost:27017")
	if err != nil {
		print(err)
		return
	}

	if err := addUser(session, &User{ID: 1, Name: "jerry"}); err != nil {
		log.Printf("error add the user to the db: %s", err.Error())
		return
	}

	user, err := getUser(session, 1)
	if err != nil {
		log.Printf("error reading the user from the db: %s", err.Error())
		return
	}
	fmt.Printf("User: %+v\n", user)
}

func addUser(session pmgo.SessionManager, user *User) error {
	return session.DB("test").C("testc").Insert(user)
}

func getUser(session pmgo.SessionManager, id int) (*User, error) {
	var user User
	err := session.DB("test").C("testc").Find(bson.M{"id": id}).One(&user)

	if err != nil {
		return nil, err
	}

	return &user, nil
}

单元测试代码

使用gomock创建Controller
pmgomock模拟mock返回数据

package main

import (
	"reflect"
	"testing"

	"github.com/globalsign/mgo/bson"
	"github.com/golang/mock/gomock"
	"github.com/gunsluo/pmgo/pmgomock"
)

func TestGetUser(t *testing.T) {
	ctrl := gomock.NewController(t)
	defer ctrl.Finish()

	user := User{
		ID:   1,
		Name: "Zapp Brannigan",
	}

	// Mock up a database, session, collection and a query and set
	// expected/returned values for each type
	query := pmgomock.NewMockQueryManager(ctrl)
	query.EXPECT().One(gomock.Any()).SetArg(0, user).Return(nil)

	collection := pmgomock.NewMockCollectionManager(ctrl)
	collection.EXPECT().Find(bson.M{"id": 1}).Return(query)

	database := pmgomock.NewMockDatabaseManager(ctrl)
	database.EXPECT().C("testc").Return(collection)

	session := pmgomock.NewMockSessionManager(ctrl)
	session.EXPECT().DB("test").Return(database)

	// Call the function we want to test. It will use the mocked interfaces
	readUser, err := getUser(session, 1)

	if err != nil {
		t.Errorf("getUser returned an error: %s\n", err.Error())
	}

	if !reflect.DeepEqual(*readUser, user) {
		t.Errorf("Users don't match. Got %+v, want %+v\n", readUser, user)
	}
}

集成测试

pmgo支持集成测试，测试开始后启动一个真实的mongo服务用于测试。需要指定mongo的服务路径: Server = pmgo.NewDBServer(); Server.SetPath(tempDir)

package main

import (
	"io/ioutil"
	"os"
	"reflect"
	"testing"

	"github.com/globalsign/mgo/bson"
	"github.com/golang/mock/gomock"
	"github.com/gunsluo/pmgo"
	"github.com/gunsluo/pmgo/pmgomock"
)

func TestGetUser(t *testing.T) {
	ctrl := gomock.NewController(t)
	defer ctrl.Finish()

	user := User{
		ID:   1,
		Name: "Zapp Brannigan",
	}

	// Mock up a database, session, collection and a query and set
	// expected/returned values for each type
	query := pmgomock.NewMockQueryManager(ctrl)
	query.EXPECT().One(gomock.Any()).SetArg(0, user).Return(nil)

	collection := pmgomock.NewMockCollectionManager(ctrl)
	collection.EXPECT().Find(bson.M{"id": 1}).Return(query)

	database := pmgomock.NewMockDatabaseManager(ctrl)
	database.EXPECT().C("testc").Return(collection)

	session := pmgomock.NewMockSessionManager(ctrl)
	session.EXPECT().DB("test").Return(database)

	// Call the function we want to test. It will use the mocked interfaces
	readUser, err := getUser(session, 1)

	if err != nil {
		t.Errorf("getUser returned an error: %s\n", err.Error())
	}

	if !reflect.DeepEqual(*readUser, user) {
		t.Errorf("Users don't match. Got %+v, want %+v\n", readUser, user)
	}
}

var Server pmgo.DBTestServer

func TestIntegration(t *testing.T) {
	setup()

	readUser, err := getUser(Server.Session(), 1)
	if err != nil {
		t.Errorf("getUser returned an error: %s\n", err.Error())
	}

	if !reflect.DeepEqual(*readUser, mockUser()) {
		t.Errorf("Users don't match. Got %+v, want %+v\n", readUser, mockUser())
	}

	tearDown()
}

func setup() {
	os.Setenv("CHECK_SESSIONS", "0")
	tempDir, err := ioutil.TempDir("", "testing")
	if err != nil {
		panic(err)
	}

	Server = pmgo.NewDBServer()
	Server.SetPath(tempDir)

	session := Server.Session()
	// load some fake data into the db
	session.DB("test").C("testc").Insert(mockUser())
}

func mockUser() User {
	return User{
		ID:   1,
		Name: "Zapp Brannigan",
	}

}

func tearDown() {
	Server.Session().Close()
	Server.Session().DB("samples").DropDatabase()
	Server.Stop()
}