go - 即使初始化后变量也为零

Question

This question already has answers here:

How to use global var across files in a package?

(2个答案)



global error variable remains nil after initialization

(2个答案)


6个月前关闭。




这是代码
config / config.go

const PROJECT_ID = "projectid"

var Ctx = context.Background()

var DSClient *datastore.Client

type Logger struct {
    Pkg string
}

func (l *Logger) Error(v ...interface{}) {
    log.Print("Error|", l.Pkg, ": ", v)
}

func (l *Logger) Info(v ...interface{}) {
    log.Print("Info|", l.Pkg, ": ", v)
}
var propFile = "${env}.properties"
var Props *properties.Properties

func init(){
    Props = properties.MustLoadFile(propFile, properties.UTF8)
    DSClient, err := datastore.NewClient(Ctx, PROJECT_ID)
    if err != nil {
        log.Fatal("Couldn't connect to DataStore: ", err)
    }
    log.Print("DataStore Client: ", DSClient)
}

index / index.go

    import (
    ...
    "github.com/shwetanka19/project/internal/config"
)
    urs := [] user.User{}
    q := datastore.NewQuery("users").Filter("email=", greq.Email).Limit(1)
    logger.Info("Now Client: ", config.DSClient)
    keys, err := config.DSClient.GetAll(config.Ctx, q, &urs)

日志

DataStore Client: &{0xc000010840 0xc000119d40 projectid}

[Now Client:  <nil>]

为什么客户端已经初始化时现在为零？在API调用期间会调用index.go中的代码。服务器启动时调用config时。

最佳答案

当你做

DSClient, err := datastore.NewClient(Ctx, PROJECT_ID)

您创建了一个新的 DSClient变量，该变量遮盖了另一个变量。您只需要将其更改为:

var err error
DSClient, err = datastore.NewClient(Ctx, PROJECT_ID)

关于go - 即使初始化后变量也为零，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/60861633/

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Answer 1

当你做

DSClient, err := datastore.NewClient(Ctx, PROJECT_ID)

您创建了一个新的 DSClient变量，该变量遮盖了另一个变量。您只需要将其更改为:

var err error
DSClient, err = datastore.NewClient(Ctx, PROJECT_ID)