go-gin中如何在中间件之间共享变量

Question

例如在 ExpressJS 中，我的路线看起来像这样router.patch('/:id/approve', AuthMiddleware.verifyToken,    AuthMiddleware.isSuperAdmin, AccommodationMiddleware.param, Accommodation.accommodationApprove);我会创建一个全局变量并在任何地方访问它 req.somevariable = somevariable这在 go-gin 中是否可行，那么如何？我需要跨中间件传递数据，但我不知道如何

Answer 1

你可以使用Context这种东西，这里是一个例子：

package main

import (

    "log"

    "net/http"

    "github.com/gin-gonic/gin"

    "github.com/gin-gonic/gin/binding"

)

type ParamsOne struct {

    Username string `json:"username"`

}

type ParamsTwo struct {

    Username string `json:"username"`

}

func first(c *gin.Context) {

    c.Set("variable", "foo")

    c.Next()

}

func second(c *gin.Context) {

    v := c.MustGet("variable")

    log.Printf("in middleware %s", v)

    c.Next()

}

func main() {

    r := gin.New()

    r.Use(first)

    r.Use(second)

    r.POST("/", func(c *gin.Context) {

        var f ParamsOne

        if err := c.ShouldBindBodyWith(&f, binding.JSON); err != nil {

            log.Printf("%+v", err)

        }

        log.Printf("%+v", f)

        var ff ParamsTwo

        if err := c.ShouldBindBodyWith(&ff, binding.JSON); err != nil {

            log.Printf("%+v", err)

        }

        log.Printf("%+v", ff)

        v := c.MustGet("variable")

        log.Printf("in route %s", v)

        c.IndentedJSON(http.StatusOK, f)

    })

    r.Run(":4000")

}

输出：

example$ ./example

[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.

 - using env:   export GIN_MODE=release

 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] POST   /                         --> main.main.func1 (3 handlers)

[GIN-debug] Listening and serving HTTP on :4000

2020/07/05 13:11:06 in middleware foo

2020/07/05 13:11:06 {Username:somename}

2020/07/05 13:11:06 {Username:somename}

2020/07/05 13:11:06 in route foo