Pointers 运行时错误：公用指针中的内存地址无效或无指针取消引用

我是一名nodejs开发人员，我通常为我的应用程序使用一个结构，其中包含一个配置包/对象，该配置包/对象包含对我经常使用的libs和配置选项的引用。通常，这个配置对象也保存我的数据库连接，并且可以通过我的应用程序访问它

我试图在go中构建类似的功能，但失败得很惨

我的计划是构建一个公共变量，它保存对我的配置结构的引用。但是当我试图调用我的

Config.Database

时，我会感到恐慌：

2017/02/19 14:05:44 http: panic serving 127.0.0.1:53554: runtime error: invalid memory address or nil pointer dereference
    goroutine 50 [running]:
    net/http.(*conn).serve.func1(0xc42027c000)
        /usr/local/go/src/net/http/server.go:1491 +0x12a
    panic(0x9f45c0, 0xc42000c100)
        /usr/local/go/src/runtime/panic.go:458 +0x243
    main.SignUp(0xc4202780e0)
        /home/attila/dev/gopath/src/github.com/attilasatan/helloiris/handlers.go:31 +0x258
    github.com/kataras/iris.HandlerFunc.Serve(0xafaf00, 0xc4202780e0)
        /home/attila/dev/gopath/src/github.com/kataras/iris/http.go:211 +0x30
    github.com/kataras/iris.(*Context).Do(0xc4202780e0)
        /home/attila/dev/gopath/src/github.com/kataras/iris/context.go:152 +0x4d
    github.com/kataras/iris.(*serveMux).BuildHandler.func1(0xc4202780e0)
        /home/attila/dev/gopath/src/github.com/kataras/iris/http.go:1059 +0x6ea
    github.com/kataras/iris.(*Framework).Build.func1.1(0xd87e20, 0xc4202701a0, 0xc420284000)
        /home/attila/dev/gopath/src/github.com/kataras/iris/iris.go:411 +0x72
    net/http.HandlerFunc.ServeHTTP(0xc420235080, 0xd87e20, 0xc4202701a0, 0xc420284000)
        /usr/local/go/src/net/http/server.go:1726 +0x44
    net/http.serverHandler.ServeHTTP(0xc420089f80, 0xd87e20, 0xc4202701a0, 0xc420284000)
        /usr/local/go/src/net/http/server.go:2202 +0x7d
    net/http.(*conn).serve(0xc42027c000, 0xd88820, 0xc42015c200)
        /usr/local/go/src/net/http/server.go:1579 +0x4b7
    created by net/http.(*Server).Serve
        /usr/local/go/src/net/http/server.go:2293 +0x44d
    2017/02/19 14:05:44 http: panic serving 127.0.0.1:53560: runtime error: invalid memory address or nil pointer dereference
    goroutine 51 [running]:
    net/http.(*conn).serve.func1(0xc42027c180)
        /usr/local/go/src/net/http/server.go:1491 +0x12a
    panic(0x9f45c0, 0xc42000c100)
        /usr/local/go/src/runtime/panic.go:458 +0x243
    main.SignUp(0xc4202ac070)
        /home/attila/dev/gopath/src/github.com/attilasatan/helloiris/handlers.go:31 +0x258
    github.com/kataras/iris.HandlerFunc.Serve(0xafaf00, 0xc4202ac070)
        /home/attila/dev/gopath/src/github.com/kataras/iris/http.go:211 +0x30
    github.com/kataras/iris.(*Context).Do(0xc4202ac070)
        /home/attila/dev/gopath/src/github.com/kataras/iris/context.go:152 +0x4d
    github.com/kataras/iris.(*serveMux).BuildHandler.func1(0xc4202ac070)
        /home/attila/dev/gopath/src/github.com/kataras/iris/http.go:1059 +0x6ea
    github.com/kataras/iris.(*Framework).Build.func1.1(0xd87e20, 0xc4202a60d0, 0xc4202840f0)
        /home/attila/dev/gopath/src/github.com/kataras/iris/iris.go:411 +0x72
    net/http.HandlerFunc.ServeHTTP(0xc420235080, 0xd87e20, 0xc4202a60d0, 0xc4202840f0)
        /usr/local/go/src/net/http/server.go:1726 +0x44
    net/http.serverHandler.ServeHTTP(0xc420089f80, 0xd87e20, 0xc4202a60d0, 0xc4202840f0)
        /usr/local/go/src/net/http/server.go:2202 +0x7d
    net/http.(*conn).serve(0xc42027c180, 0xd88820, 0xc42015c480)
        /usr/local/go/src/net/http/server.go:1579 +0x4b7
    created by net/http.(*Server).Serve

这是我的配置文件。如您所见，我正在使用

tideland/golib/redis

进行redis连接

配置。转到

package main

import (
    "fmt"
    "strconv"
    "time"

    "github.com/tideland/golib/redis"
)

/*Configuration is the main type of app configuration */
type Configuration struct {
    Database *redis.Connection
}

/*Config is app configuration holder */
var Config *Configuration

/*Configure handles database connection */
func Configure() (*Configuration, error) {

    db, err := redis.Open(redis.TcpConnection("127.0.0.1:6379", 30*time.Second))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }
    conn, err := db.Connection()

    n, _ := conn.DoInt("INCR", "IDIDID")

    fmt.Printf(strconv.Itoa(n))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }

    /*Config is the main configuration object*/

    Config := &Configuration{conn}

    return Config, err
}

func SignUp(ctx *iris.Context) {
    mail := ctx.FormValue("email")
    password := ctx.FormValue("password")
    passwordConfirm := ctx.FormValue("password-confirm")

    if password != passwordConfirm {
        ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
    } else {

        user := User{mail, password, 0}
        db := Config.Database

        userID, err := db.DoInt("INCR", "HELLOIRIS:ID")

        if err != nil {
            ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
        } else {

            user.ID = userID

            fmt.Printf("SAVED")

            ctx.Render("signup-success.html", nil)
        }
        ctx.JSON(200, user)
    }
}

func Configure() (Config *Configuration, err error) {

    if Config != nil {
    return
    }
}

config, err := Configure()

if err != nil {
    ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"try again later"})
    return
}

user := User{mail, password, 0}
db := config.Database

这里是我使用

Config.Database

的地方

处理程序。转到

package main

import (
    "fmt"
    "strconv"
    "time"

    "github.com/tideland/golib/redis"
)

/*Configuration is the main type of app configuration */
type Configuration struct {
    Database *redis.Connection
}

/*Config is app configuration holder */
var Config *Configuration

/*Configure handles database connection */
func Configure() (*Configuration, error) {

    db, err := redis.Open(redis.TcpConnection("127.0.0.1:6379", 30*time.Second))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }
    conn, err := db.Connection()

    n, _ := conn.DoInt("INCR", "IDIDID")

    fmt.Printf(strconv.Itoa(n))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }

    /*Config is the main configuration object*/

    Config := &Configuration{conn}

    return Config, err
}

func SignUp(ctx *iris.Context) {
    mail := ctx.FormValue("email")
    password := ctx.FormValue("password")
    passwordConfirm := ctx.FormValue("password-confirm")

    if password != passwordConfirm {
        ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
    } else {

        user := User{mail, password, 0}
        db := Config.Database

        userID, err := db.DoInt("INCR", "HELLOIRIS:ID")

        if err != nil {
            ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
        } else {

            user.ID = userID

            fmt.Printf("SAVED")

            ctx.Render("signup-success.html", nil)
        }
        ctx.JSON(200, user)
    }
}

func Configure() (Config *Configuration, err error) {

    if Config != nil {
    return
    }
}

config, err := Configure()

if err != nil {
    ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"try again later"})
    return
}

user := User{mail, password, 0}
db := config.Database

失败后，我更改了

配置
功能，如下所示：

配置。转到

package main

import (
    "fmt"
    "strconv"
    "time"

    "github.com/tideland/golib/redis"
)

/*Configuration is the main type of app configuration */
type Configuration struct {
    Database *redis.Connection
}

/*Config is app configuration holder */
var Config *Configuration

/*Configure handles database connection */
func Configure() (*Configuration, error) {

    db, err := redis.Open(redis.TcpConnection("127.0.0.1:6379", 30*time.Second))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }
    conn, err := db.Connection()

    n, _ := conn.DoInt("INCR", "IDIDID")

    fmt.Printf(strconv.Itoa(n))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }

    /*Config is the main configuration object*/

    Config := &Configuration{conn}

    return Config, err
}

func SignUp(ctx *iris.Context) {
    mail := ctx.FormValue("email")
    password := ctx.FormValue("password")
    passwordConfirm := ctx.FormValue("password-confirm")

    if password != passwordConfirm {
        ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
    } else {

        user := User{mail, password, 0}
        db := Config.Database

        userID, err := db.DoInt("INCR", "HELLOIRIS:ID")

        if err != nil {
            ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
        } else {

            user.ID = userID

            fmt.Printf("SAVED")

            ctx.Render("signup-success.html", nil)
        }
        ctx.JSON(200, user)
    }
}

func Configure() (Config *Configuration, err error) {

    if Config != nil {
    return
    }
}

config, err := Configure()

if err != nil {
    ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"try again later"})
    return
}

user := User{mail, password, 0}
db := config.Database

我改变了handler的用法

处理程序。转到

package main

import (
    "fmt"
    "strconv"
    "time"

    "github.com/tideland/golib/redis"
)

/*Configuration is the main type of app configuration */
type Configuration struct {
    Database *redis.Connection
}

/*Config is app configuration holder */
var Config *Configuration

/*Configure handles database connection */
func Configure() (*Configuration, error) {

    db, err := redis.Open(redis.TcpConnection("127.0.0.1:6379", 30*time.Second))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }
    conn, err := db.Connection()

    n, _ := conn.DoInt("INCR", "IDIDID")

    fmt.Printf(strconv.Itoa(n))

    if err != nil {
        fmt.Printf("Database connection error")
        return nil, err
    }

    /*Config is the main configuration object*/

    Config := &Configuration{conn}

    return Config, err
}

func SignUp(ctx *iris.Context) {
    mail := ctx.FormValue("email")
    password := ctx.FormValue("password")
    passwordConfirm := ctx.FormValue("password-confirm")

    if password != passwordConfirm {
        ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
    } else {

        user := User{mail, password, 0}
        db := Config.Database

        userID, err := db.DoInt("INCR", "HELLOIRIS:ID")

        if err != nil {
            ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"passwords dont match"})
        } else {

            user.ID = userID

            fmt.Printf("SAVED")

            ctx.Render("signup-success.html", nil)
        }
        ctx.JSON(200, user)
    }
}

func Configure() (Config *Configuration, err error) {

    if Config != nil {
    return
    }
}

config, err := Configure()

if err != nil {
    ctx.RenderWithStatus(iris.StatusBadRequest, "400.html", ErrorPageData{"try again later"})
    return
}

user := User{mail, password, 0}
db := config.Database

。。。一切都开始完美运转

我的问题是我不明白为什么。。。为什么当我使用一个公共指针时会有这种恐慌，为什么当我从一个函数返回同一个指针时不会有这种恐慌

Config := &Configuration{conn}

此行创建了一个新的本地变量
Config
，因此全局
Config
永远不会设置为任何值。删除
：
以不创建新变量，并改用全局
配置
。
您会遇到此问题，因为您的
配置
全局变量未设置或仍然保持零值。正如错误所说：

运行时错误：无效内存地址或零指针取消引用

一定要打电话
func Configure（）

当您在配置文件中将
conn
redis分配给全局变量时，请删除
：
，如下所示：

Config = &Configuration{conn}