golang gin-gonic/gin framework use another param instead of callback

Question

in my case, I want to use anothor param instead of callback

my url: http://example.com?id=1&cb=callback1

but I found this in the source code:

// JSONP serializes the given struct as JSON into the response body.
// It adds padding to response body to request data from a server residing in a different domain than the client.
// It also sets the Content-Type as "application/javascript".
func (c *Context) JSONP(code int, obj interface{}) {
    callback := c.DefaultQuery("callback", "")
    if callback == "" {
        c.Render(code, render.JSON{Data: obj})
        return
    }
    c.Render(code, render.JsonpJSON{Callback: callback, Data: obj})
}

how can I use the param cb instead of callback

Answer 1

You can use middleware for gin. Modifying the query before it is parsed.

package main

import (
    "fmt"
    "github.com/gin-gonic/gin"
    "net/url"
)

func main() {
    r := gin.Default()
    r.Use(func(context *gin.Context) {
        req := context.Request
        urlCopy, _ := req.URL.Parse(req.RequestURI)
        if cb := urlCopy.Query().Get("cb"); cb != "" {
            req.URL.RawQuery += fmt.Sprintf("&callback=%s", url.QueryEscape(cb))
        }
    })

    r.GET("/ping", func(c *gin.Context) {
        c.JSONP(400, 1)
    })
    r.Run() // listen and serve on 0.0.0.0:8080 (for windows "localhost:8080")
}