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 mainimport (    "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 :40002020/07/05 13:11:06 in middleware foo2020/07/05 13:11:06 {Username:somename}2020/07/05 13:11:06 {Username:somename}2020/07/05 13:11:06 in route foo