Query Param - Replacing + by blank in golang

I am using golang

func (ph *testHandler) GetData() gin.HandlerFunc {
	return func(ctx *gin.Context) {
		params := ctx.Request.URL.Query()
        search = strings.TrimSpace(params.Get("data"))
   } 
}

here I am passing 'test+test' in url but I am getting 'test test'

How can I do query parsing in golang

If you look at the source

func (u *URL) Query() Values {
        v, _ := ParseQuery(u.RawQuery)
        return v
}

Calls ParseQuery which calls unescape in the "encodeQueryComponent" mode
as part of the things it does.

this code fragment is relevant

            case '+':
                    if mode == encodeQueryComponent {
                            t.WriteByte(' ')
                    } else {
                            t.WriteByte('+')
                    }

this is simply RFC compliant parsing, it's normal, the behaviour
you are seeing is expected

see https://cs.opensource.google/go/go/+/refs/tags/go1.16.6:src/net/url/url.go;drc=refs%2Ftags%2Fgo1.16.6;l=182

The browsers treats + and %20 signs in URL as space character so test+test in query parameter will have value test test.
To prevent this you have to manually add URL encoded value of + character literal in the URL - https://example.com?data=test%2Btest

For other URL encoded values see w3schools.

The plus sign in the value of your query parameter is actually an URL-encoded ASCII space. If you want to obtain "test+test" in the backend, you should percent-encode the plus sign in the value of the URL's query param: test%2Btest.

Some minimal server code to fix ideas:

package main

import (
	"fmt"
	"log"
	"net/http"
)

func main() {
	http.HandleFunc("/", handle)
	if err := http.ListenAndServe(":8080", nil); err != nil {
		log.Fatal(err)
	}
}

func handle(w http.ResponseWriter, r *http.Request) {
	data := r.URL.Query().Get("data")
	w.Header().Set("Content-type", "text/plain")
	fmt.Fprint(w, data)
}

Results:

• http://localhost:8080/?data=test+test prints test test, whereas
• http://localhost:8080/?data=test%2Btest prints test+test.