Go: 客户端已断开连接

huangapple
go评论121阅读模式
英文:

Go: client is disconnected

问题

我加入Gophers团队已经有几周了。到目前为止一切顺利。
我正在使用一个fiber网络框架来构建后端API。

我正在使用MongoDB作为我的数据库。

database/db.go

  1. package database
  3. import (
  4. 	"context"
  5. 	"log"
  6. 	"time"
  8. 	"go.mongodb.org/mongo-driver/mongo"
  9. 	"go.mongodb.org/mongo-driver/mongo/options"
  10. 	"go.mongodb.org/mongo-driver/mongo/readpref"
  11. )
  13. var DB *mongo.Database
  15. // InitMongo : 初始化mongodb...
  16. func connectToMongo() {
  17. 	log.Printf("初始化数据库")
  19. 	client, err := mongo.NewClient(options.Client().ApplyURI("mongodb://localhost:27017"))
  20. 	if err != nil {
  21. 		log.Fatal("无法连接到数据库，原因：", err)
  22. 	}
  23. 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
  25. 	err = client.Connect(ctx)
  26. 	if err != nil {
  27. 		log.Fatal("上下文错误，mongoDB：", err)
  28. 	}
  30. 	// 取消上下文以避免内存泄漏
  31. 	defer cancel()
  33. 	defer client.Disconnect(ctx)
  35. 	// 检查数据库连接
  36. 	err = client.Ping(context.Background(), readpref.Primary())
  37. 	if err != nil {
  38. 		log.Fatal("Ping, mongoDB：", err)
  39. 	}
  41. 	log.Printf("数据库已连接！")
  43. 	// 创建一个数据库
  44. 	DB = client.Database("golang-test")
  46. 	return
  47. }
  49. // 在Golang中，init()函数在调用包时总是初始化。
  50. // 因此，每当调用DB变量时，init()函数都会初始化
  51. func init() {
  52. 	connectToMongo()
  53. }

controllers/mongo.controller/mongo.controller.go

  1. package mongocontroller
  3. import (
  4. 	"log"
  6. 	"github.com/gofiber/fiber/v2"
  7. 	service "gitlab.com/.../services/mongoservice"
  8. )
  10. // GetPersons godoc
  11. // @Summary 获取人员信息。
  12. // @Description 获取人员信息
  13. // @Tags persons
  14. // @Produce json
  15. // @Success 200 {object} []service.Person
  16. // @Failure 400 {object} httputil.HTTPError
  17. // @Failure 404 {object} httputil.HTTPError
  18. // @Failure 500 {object} httputil.HTTPError
  19. // @Router /v1/persons [get]
  20. func GetPersons(c *fiber.Ctx) error {
  21. 	res, err := service.GetPersons()
  22. 	if err != nil {
  23. 		log.Fatal("ERROR: 在控制器中...", err)
  24. 	}
  26. 	return c.JSON(res)
  27. }

services/mongoservice/mongo.service.go

  1. package mongoservice
  3. import (
  4. 	"context"
  5. 	"log"
  7. 	database "gitlab.com/.../database"
  8. 	"go.mongodb.org/mongo-driver/bson"
  9. 	"go.mongodb.org/mongo-driver/bson/primitive"
  10. )
  12. // Person : ...
  13. type Person struct {
  14. 	ID   primitive.ObjectID `bson:"_id,omitempty" json:"_id,omitempty"`
  15. 	Name string             `bson:"name,omitempty" json:"name,omitempty"`
  16. 	Age  int                `bson:"age,omitempty" json:"age,omitempty"`
  17. }
  20. func GetPersons() ([]Person, error) {
  22. 	ctx := context.Background()
  24. 	persons := []Person{}
  26. 	log.Printf("mongo数据...", ctx)
  28. 	cur, err := database.DB.Collection("persons").Find(ctx, bson.M{})
  29. 	if err != nil {
  30. 		log.Fatal(err)
  31. 	}
  33. 	// 遍历返回的游标。
  34. 	for cur.Next(ctx) {
  35. 		var person Person
  36. 		cur.Decode(&person)
  37. 		persons = append(persons, person)
  38. 	}
  40. 	defer cur.Close(ctx)
  42. 	return persons, err
  43. }

这是我存储在数据库中的数据：

Go: 客户端已断开连接

问题是，服务中的**cur, err := database.DB.Collection("persons").Find(ctx, bson.M{})**这一行总是抛出Client is disconnected的错误。

感谢您的帮助！

谢谢。

英文:

It's been few weeks since I joined in Gophers team. So far so good.
I started a new project using a fiber web framework to build backend APIs.

I am using MongoDB as my database.

database/db.go

  1. package database
  3. import (
  4. 	"context"
  5. 	"log"
  6. 	"time"
  8. 	"go.mongodb.org/mongo-driver/mongo"
  9. 	"go.mongodb.org/mongo-driver/mongo/options"
  10. 	"go.mongodb.org/mongo-driver/mongo/readpref"
  11. )
  13. var DB *mongo.Database
  15. // InitMongo : Initialize mongodb...
  16. func connectToMongo() {
  17. 	log.Printf("Initializing database")
  19. 	client, err := mongo.NewClient(options.Client().ApplyURI("mongodb://localhost:27017"))
  20. 	if err != nil {
  21. 		log.Fatal("Could not able to connect to the database, Reason:", err)
  22. 	}
  23. 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
  25. 	err = client.Connect(ctx)
  26. 	if err != nil {
  27. 		log.Fatal("Context error, mongoDB:", err)
  28. 	}
  30. 	//Cancel context to avoid memory leak
  31. 	defer cancel()
  33. 	defer client.Disconnect(ctx)
  35. 	// Ping our db connection
  36. 	err = client.Ping(context.Background(), readpref.Primary())
  37. 	if err != nil {
  38. 		log.Fatal("Ping, mongoDB:", err)
  39. 	}
  41. 	log.Printf("Database connected!")
  43. 	// Create a database
  44. 	DB = client.Database("golang-test")
  46. 	return
  47. }
  49. // In Golang, init() functions always initialize whenever the package is called.
  50. // So, whenever DB variable called, the init() function initialized
  51. func init() {
  52. 	connectToMongo()
  53. }

controllers/mongo.controller/mongo.controller.go

  1. package mongocontroller
  3. import (
  4. 	"log"
  6. 	"github.com/gofiber/fiber/v2"
  7. 	service "gitlab.com/.../services/mongoservice"
  8. )
  10. // GetPersons godoc
  11. // @Summary Get persons.
  12. // @Description Get persons
  13. // @Tags persons
  14. // @Produce json
  15. // @Success 200 {object} []service.Person
  16. // @Failure 400 {object} httputil.HTTPError
  17. // @Failure 404 {object} httputil.HTTPError
  18. // @Failure 500 {object} httputil.HTTPError
  19. // @Router /v1/persons [get]
  20. func GetPersons(c *fiber.Ctx) error {
  21. 	res, err := service.GetPersons()
  22. 	if err != nil {
  23. 		log.Fatal("ERROR: in controller...", err)
  24. 	}
  26. 	return c.JSON(res)
  27. }

services/mongoservice/mongo.service.go

  1. package mongoservice
  3. import (
  4. 	"context"
  5. 	"log"
  7. 	database "gitlab.com/.../database"
  8. 	"go.mongodb.org/mongo-driver/bson"
  9. 	"go.mongodb.org/mongo-driver/bson/primitive"
  10. )
  12. // Person : ...
  13. type Person struct {
  14. 	ID   primitive.ObjectID `bson:"_id,omitempty" json:"_id,omitempty"`
  15. 	Name string             `bson:"name,omitempty" json:"name,omitempty"`
  16. 	Age  int                `bson:"age,omitempty" json:"age,omitempty"`
  17. }
  20. func GetPersons() ([]Person, error) {
  22. 	ctx := context.Background()
  24. 	persons := []Person{}
  26. 	log.Printf("mongo data...", ctx)
  28. 	cur, err := database.DB.Collection("persons").Find(ctx, bson.M{})
  29. 	if err != nil {
  30. 		log.Fatal(err)
  31. 	}
  33. 	// Iterate through the returned cursor.
  34. 	for cur.Next(ctx) {
  35. 		var person Person
  36. 		cur.Decode(&person)
  37. 		persons = append(persons, person)
  38. 	}
  40. 	defer cur.Close(ctx)
  42. 	return persons, err
  43. }

Here is my data stored in the database:

Go: 客户端已断开连接

The problem is, the line cur, err := database.DB.Collection("persons").Find(ctx, bson.M{}) from service always throwing Client is disconnected.

Any help is appreciated!

Thank you.

答案1

得分: 8

你正在同一个函数中调用defer client.Disconnect(ctx)，而这个函数是用来创建连接的（connectToMongo），所以在调用完函数后会关闭连接。你应该在完成任务后返回连接并关闭。我指的是这些部分：
defer cancel()
defer client.Disconnect(ctx)

英文:

You are calling defer client.Disconnect(ctx) in the same function which is creating the connection (connectToMongo ) so it will close the connection after calling the function. You should return the connection and close after finishing your task. I mean these parts:
defer cancel()
defer client.Disconnect(ctx)

huangapple
  • 本文由 发表于 2021年8月17日 20:09:53
  • 转载请务必保留本文链接：https://go.coder-hub.com/68817123.html
  • go
  • go-fiber
  • mongodb
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定