Golang无法在MongoDB中创建文档

问题内容

我正在尝试将文档插入 mongodb，但尽管成功连接到 mongo，但我仍然收到以下错误：

http: panic serving 172.27.0.8:40176: runtime error: invalid memory address or nil pointer dereference

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我正在初始化数据库连接的 main.go 看起来像这样

func main(){

//connect to mongo
mongoclient,err:=connecttomongo()
if err!=nil{
log.panic(err)
}
client=mongoclient

//create a context that mongo needs in order to disconnect
ctx,_:=context.withtimeout(context.background(), 15*time.second)
// ctx,cancel:=context.withtimeout(context.background(), 15*time.second)
//defer cancel()

//close connection
defer func () {
if err =client.disconnect(ctx); err!=nil{
panic(err)
}
}()

muxrouter := mux.newrouter().strictslash(true)

//specify who's allowed to connect
c:=cors.new(cors.options{
allowedorigins: []string{"https://*", "http://*"},
allowedmethods: []string{"get", "post", "put", "delete", "options"},
allowedheaders: []string{"accept", "authorization", "content-type", "x-csrf-token"},
exposedheaders: []string{"link"},
allowcredentials: true,
maxage: 300,
})
router := addroutes(muxrouter)
handler := c.handler(router)
log.println("service stratring at o port ",webport)

sterr := http.listenandserve(":9090", handler) //uncomment this line when using docker
if sterr != nil {
log.fatal("error starting http server :: ", err)
return
}

log.println("service started at port ",webport)

}

func connecttomongo()(*mongo.client,error){
mongousername := os.getenv("mongousername")
mongopassword := os.getenv("mongopassword")
//create connection options
clientoptions:=options.client().applyuri(mongourl)
clientoptions.setauth(options.credential{
username: mongousername,
password: mongopassword,
})

//connect
c,err:=mongo.connect(context.todo(),clientoptions)
if err!=nil{
log.println("error connecting to mongo",err)
return nil,err
}
log.println("connected to mongo")
return c,nil
}

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在一个单独的文件 models.go 中，我尝试将数据插入数据库，如下所示：

var client *mongo.Client
func Insert(entry LogEntry)error{
log.Printf("Attempting to insert %s", entry)
log.Printf("client s %s", client)
//db:=client.Database("logs")
//log.Printf("database is %s", db)

collection:=client.Database("logs").Collection("logsCollection")
log.Printf("collection is %s", collection)

_,err :=collection.InsertOne(context.TODO(), LogEntry{
Name: entry.Name,
Data: entry.Data,
CreatedAt: time.Now(),
UpdatedAt: time.Now(),
})
if err!=nil{
log.Println("Error inserting new record into logs collection",err)
return err
}
log.Println("insert successful")
return nil
}

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有人能发现我做错了什么吗？

解决方法

由于错误是通用的（例如，未提供错误的行号），我将分享一个可行的解决方案，也许可以帮助您找出问题所在。我先分享一下代码。

main.go 文件

package main

import (
"context"
"fmt"
"time"

"go.mongodb.org/mongo-driver/bson"
"go.mongodb.org/mongo-driver/mongo"
"go.mongodb.org/mongo-driver/mongo/options"
)

type LogEntry struct {
Name string
Data string
CreatedAt time.Time
UpdatedAt time.Time
}

func main() {
ctx, cancel := context.WithTimeout(context.Background(), time.Second*20)
defer cancel()

clientOptions := options.Client().ApplyURI("mongodb://root:root@localhost:27017")
mongoClient, err := mongo.Connect(ctx, clientOptions)
if err != nil {
panic(err)
}
defer mongoClient.Disconnect(ctx)

demoDb := mongoClient.Database("demodb")
myCollection := demoDb.Collection("myCollection")

// delete documents
if _, err := myCollection.DeleteMany(ctx, bson.M{}); err != nil {
panic(err)
}

// insert data
insertRes, err := myCollection.InsertOne(ctx, LogEntry{
Name: "lorem ipsum",
Data: "lorem ipsum",
CreatedAt: time.Now(),
UpdatedAt: time.Now(),
})
if err != nil {
panic(err)
}
fmt.Println(insertRes.InsertedID)

// query data
cursor, err := myCollection.Find(ctx, bson.M{})
if err != nil {
panic(err)
}
var logEntries []bson.M
if err = cursor.All(ctx, &logEntries); err != nil {
panic(err)
}
for _, v := range logEntries {
fmt.Println(v)
}
}

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为了演示，我将所有逻辑放在一个文件中。在此文件中，我执行了以下步骤：

最后要提到的是我用来运行容器的 docker 命令：

docker运行-d -p 27017:27017 --name mymongo -e mongo_initdb_root_username=root -e mongo_initdb_root_password=root mongo:latest

如果您坚持使用我的解决方案，您应该能够毫无问题地插入文档。如果不是这样，请告诉我，我会尽力帮助您！

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