Gin wrong response after returning error at middleware

Description

i have my own middelware which takes data from queryParama and adds it to the context (in my example it's name) if name is not given, an error is returned and the request is not further processed with a response code of 400. The problem is that if I call a non-existent URL, e.g. /xxxhello , without the name parameter, I also get a 400, and I would expect a 404. I can get a 404 if I add the ?name=value parameter, but that doesn't make much sense

How to reproduce

package main

import (
    "context"
    "errors"
    "github.com/gin-gonic/gin"
    "log"
    "net/http"
)

func main() {
    g := gin.Default()
    g.Use(myMiddleware())
    g.GET("/hello", func(c *gin.Context) {
        c.String(200, "Hello %s", c.Request.Context().Value("name"))
    })
    g.Run(":9000")
}

func myMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        req := c.Request
        nameParam := req.URL.Query().Get("name")
        if nameParam == "" {
            log.Println("param is empty")
            c.AbortWithError(http.StatusBadRequest, errors.New("param is empty"))
            return
        }
        req = req.WithContext(context.WithValue(req.Context(), "name", nameParam))
        c.Request = req
        c.Next()
    }
}

Expectations

$ curl http://localhost:9000/xxxhello
404 - not found

Actual result

$ curl -i http://localhost:9000/xxxhello
400 - bad request

Environment

• go version: 1.21.0
• gin version (or commit ref): v1.9.0
• operating system: Linux/Windows

Comment From: AuroraTea

if !c.Writer.Written() {
    // TODO: 404
}

Comment From: VarusHsu

You should group your router at first. Let the middleware only affect a group instead of the global location.

package main

import (
    "context"
    "errors"
    "github.com/gin-gonic/gin"
    "log"
    "net/http"
)

func main() {
    g := gin.Default()

    group := g.Group("")
    group.Use(myMiddleware())
    {
        group.GET("/hello1", func(c *gin.Context) {
            c.String(200, "Hello1 %s", c.Request.Context().Value("name"))
        })
        group.GET("/hello2", func(c *gin.Context) {
            c.String(200, "Hello2 %s", c.Request.Context().Value("name"))
        })
        group.GET("/hello3", func(c *gin.Context) {
            c.String(200, "Hello3 %s", c.Request.Context().Value("name"))
        })
    }
    g.GET("/hello", func(c *gin.Context) {
        c.String(200, "Hello %s", c.Request.Context().Value("name"))
    })
    g.Run(":9000")
}

func myMiddleware() gin.HandlerFunc {
    return func(c *gin.Context) {
        req := c.Request
        nameParam := req.URL.Query().Get("name")
        if nameParam == "" {
            log.Println("param is empty")
            c.AbortWithError(http.StatusBadRequest, errors.New("param is empty"))
            return
        }
        req = req.WithContext(context.WithValue(req.Context(), "name", nameParam))
        c.Request = req
        c.Next()
    }
}

Comment From: mkruczek

@VarusHsu yours solution is good for me, thank you :)