如何在中间件 go-chi 中获取 url 参数

Question

我为特定的路由集使用特定的中间件

r.Route("/platform", func(r chi.Router) {
    r.Use(authService.AuthMiddleware)
    r.Get("/{id}/latest", RequestPlatformVersion)
})

现在我如何访问这个AuthMiddleware 中间件中的id url 参数

func (s *Service) AuthMiddleware(h http.Handler) http.Handler {
    fn := func(w http.ResponseWriter, r *http.Request) {
        fmt.Println(chi.URLParam(r, "id"))
        id := chi.URLParam(r, "id")
        
        if id > 100 {
          http.Error(w, errors.New("Error").Error(), http.StatusUnauthorized)
          return
        }
    }
    return http.HandlerFunc(fn)
}

但是，即使正在运行中间件并且正在调用特定路由，id 参数也会打印为空字符串

Answer 1

您将chi.URLParam 放在路径参数{id} 之前，而您忘记将.ServeHTTP(w, r) 放在中间件中。如果你不放那个东西，你的请求就不会进入 Route 内部的路径中。

这是工作示例：

package main

import (
    "fmt"
    "net/http"

    "github.com/go-chi/chi"
)

func AuthMiddleware(h http.Handler) http.Handler {
    fn := func(w http.ResponseWriter, r *http.Request) {
        fmt.Println(chi.URLParam(r, "id"))
        h.ServeHTTP(w, r)
    }
    return http.HandlerFunc(fn)
}

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

    r.Route("/platform/{id}", func(r chi.Router) {
        r.Use(AuthMiddleware)
        r.Get("/latest", func(rw http.ResponseWriter, r *http.Request) {
            fmt.Println("here ", chi.URLParam(r, "id")) // <- here
        })
    })

    http.ListenAndServe(":8080", r)
}

我将{id} 移动到platform/{id} 以便中间件获得id 路径值，并在中间件中添加h.ServeHTTP(w, r)。

尝试访问http://localhost:8080/platform/1/latest

输出将是：

1
here  1

更新

在代码之后运行验证不好，你必须修复你定义路径的方式，并在验证后移动.ServeHTTP。

这是一个例子：

package main

import (
    "errors"
    "fmt"
    "net/http"
    "strconv"

    "github.com/go-chi/chi"
)

func AuthMiddleware(h http.Handler) http.Handler {
    fn := func(w http.ResponseWriter, r *http.Request) {
        fmt.Printf("Middleware First, id: %+v\n", chi.URLParam(r, "id"))
        id, _ := strconv.Atoi(chi.URLParam(r, "id"))

        if id > 100 {
            http.Error(w, errors.New("Error").Error(), http.StatusUnauthorized)
            return
        }
        h.ServeHTTP(w, r)
    }
    return http.HandlerFunc(fn)
}

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

    // This works too ()
    // r.Route("/platform/{id}", func(r chi.Router) {
    //  r.Use(AuthMiddleware)
    //  r.Get("/latest", func(rw http.ResponseWriter, r *http.Request) {
    //      fmt.Println("second: ", chi.URLParam(r, "id")) // <- here
    //  })
    // })

    // Other Solution (Wrapping Middleware)
    r.Route("/platform", func(r chi.Router) {
        r.Get("/{id}/latest", AuthMiddleware(http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
            fmt.Println("second: ", chi.URLParam(r, "id")) // <- here
        })).ServeHTTP)
    })

    http.ListenAndServe(":8080", r)
}