Go Gorilla Mux MiddlewareFunc 与 r.Use 并返回错误答案

【问题标题】：Go Gorilla Mux MiddlewareFunc with r.Use and returning errorsGo Gorilla Mux MiddlewareFunc 与 r.Use 并返回错误
【发布时间】：2019-01-31 01:00:06
【问题描述】：

您如何设置 Gorilla Mux r.Use 以在中间件链中返回错误？ https://godoc.org/github.com/gorilla/mux#Router.Use

Main.go

r := mux.NewRouter()

r.Use(LoggingFunc)
r.Use(AuthFunc)

基本中间件

从日志中间件开始，它可以捕获和处理更下游的错误

type HandlerFunc func(w http.ResponseWriter, r *http.Request) error

func LoggingFunc(next HandlerFunc) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        // Logging middleware

        defer func() {
            if err, ok := recover().(error); ok {
                w.WriteHeader(http.StatusInternalServerError)
            }
        }()

        err := next(w, r)
        if err != nil {
            // log error
        }
    })
}

下一个中间件处理身份验证并向日志中间件返回错误。

func AuthFunc(next HandlerFunc) HandlerFunc {
    return func(w http.ResponseWriter, r *http.Request) error {

        if r.GET("JWT") == "" {
            return fmt.Errorf("No JWT")
        }

        return next(w, r)
    }
}

我不断收到类似的错误

  cannot use AuthFunc (type func(handlers.HandlerFunc) http.Handler) as type mux.MiddlewareFunc in argument to r.Use

谢谢

【问题讨论】：

AuthFunc 应该返回 http.Handler 而不是 HandlerFunc 类型

标签： go

【解决方案1】：

根据mux.Use doc，它的参数类型是MiddlewareFunc，返回类型是http.Handler而不是错误类型。你必须定义哪个返回类型是http.HandlerFunc

type Middleware func(http.HandlerFunc) http.HandlerFunc

func main() {
    r := mux.NewRouter()

    //  execute middleware from right to left of the chain
    chain := Chain(SayHello, AuthFunc(), LoggingFunc())
    r.HandleFunc("/", chain)

    println("server listening :  8000")
    http.ListenAndServe(":8000", r)
}

// Chain applies middlewares to a http.HandlerFunc
func Chain(f http.HandlerFunc, middlewares ...Middleware) http.HandlerFunc {
    for _, m := range middlewares {
        f = m(f)
    }
    return f
}

func LoggingFunc() Middleware {
    return func(next http.HandlerFunc) http.HandlerFunc {
        return func(w http.ResponseWriter, r *http.Request) {
            // Loggin middleware

            defer func() {
                if _, ok := recover().(error); ok {
                    w.WriteHeader(http.StatusInternalServerError)
                }
            }()

            // Call next middleware/handler in chain
            next(w, r)
        }
    }
}

func AuthFunc() Middleware {
    return func(next http.HandlerFunc) http.HandlerFunc {
        return func(w http.ResponseWriter, r *http.Request) {

            if r.Header.Get("JWT") == "" {
                fmt.Errorf("No JWT")
                return
            }

            next(w, r)
        }
    }

}

func SayHello(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "Hello client")
}

它将执行LogginFunc，然后是AuthFunc，然后是SayHello方法，这是您通过所有这些中间件后想要的方法。

【讨论】：