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mongodb - Golang MongoDB 错误 : result argument must be a slice address

转载 作者:IT王子 更新时间:2023-10-29 00:55:31 25 4
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我有一个函数需要从 mongoDB 集合中检索所有用户,当我尝试通过 REST 端点调用它时会抛出错误。函数是:

func (usercontroller UserController) GetAllUsers(w http.ResponseWriter, r *http.Request, p httprouter.Params) {
session := usercontroller.session.Copy()
defer session.Close()

// Stub user
result := models.User{}

// get all users
if err := session.DB("Auth").C("users").Find(nil).All(&result); err != nil {
w.WriteHeader(404)
return
}

// Marshal provided interface into JSON structure
mResult, _ := json.Marshal(result)

// Write content-type, statuscode, and the data package
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(200)
fmt.Fprintf(w, "%s", mResult)
}

错误是:

2016/06/25 16:00:21 http: panic serving 127.0.0.1:49898: result argument must be a slice address
goroutine 13 [running]:
net/http.(*conn).serve.func1(0xc82005e380)
/usr/lib/go-1.6/src/net/http/server.go:1389 +0xc1
panic(0x729b60, 0xc82000ba50)
/usr/lib/go-1.6/src/runtime/panic.go:443 +0x4e9
gopkg.in/mgo%2ev2.(*Iter).All(0xc8201280f0, 0x704600, 0xc82007e360, 0x0, 0x0)
/root/work/src/gopkg.in/mgo.v2/session.go:3696 +0x742
gopkg.in/mgo%2ev2.(*Query).All(0xc8200bc600, 0x704600, 0xc82007e360, 0x0, 0x0)
/root/work/src/gopkg.in/mgo.v2/session.go:3723 +0x4f
Auth-REST-Server/controllers.UserController.GetAllUsers(0xc82000d040, 0x7f3c1b9bf950, 0xc820061c70, 0xc8200c6380, 0x0, 0x0, 0x0)
/root/work/src/Auth-REST-Server/controllers/user.go:34 +0x251
Auth-REST-Server/controllers.(UserController).GetAllUsers-fm(0x7f3c1b9bf950, 0xc820061c70, 0xc8200c6380, 0x0, 0x0, 0x0)
/root/work/src/Auth-REST-Server/server.go:21 +0x5f
github.com/julienschmidt/httprouter.(*Router).ServeHTTP(0xc820016380, 0x7f3c1b9bf950, 0xc820061c70, 0xc8200c6380)
/root/work/src/github.com/julienschmidt/httprouter/router.go:344 +0x195
net/http.serverHandler.ServeHTTP(0xc820122000, 0x7f3c1b9bf950, 0xc820061c70, 0xc8200c6380)
/usr/lib/go-1.6/src/net/http/server.go:2081 +0x19e
net/http.(*conn).serve(0xc82005e380)
/usr/lib/go-1.6/src/net/http/server.go:1472 +0xf2e
created by net/http.(*Server).Serve
/usr/lib/go-1.6/src/net/http/server.go:2137 +0x44e

我在这里做错了什么。我以为我可以调用 Find(nil).All(&result) 并相应地检索所有记录。

最佳答案

在你的代码中你有:

// Stub user
result := models.User{}

因此结果表示单个用户,但您需要数据库中的所有用户,因此应执行以下操作:

// Stub user
result := make([]models.User, 0, 10) // Here you can specify a len and a cap.

这样,结果就是 models.User 的一部分。

此外,在 Golang 中,您永远不应该忽略错误:

// Marshal provided interface into JSON structure
mResult, _ := json.Marshal(result)

应该是:

// Marshal provided interface into JSON structure
mResult, err := json.Marshal(result)
if err != nil {
// do something with the error (log it or write it in the response)
}

编辑:我更新了代码,很抱歉。

关于mongodb - Golang MongoDB 错误 : result argument must be a slice address,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/38033834/

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