Golang : Get query string value on a POST request

In this tutorial, we will learn how to configure your Golang web application(in HTTP handler) to accept query string input by POST request such as :

 http://example.com/query?firstparameter=somevalue&secondparameter=somevalue

Golang's net/url.URL.Query will parse query string and returns the corresponding values. All you have to do is the invoke the Get() method to get the values that you are looking for.

For example :

 package main

 import (
 "fmt"
 "net/http"
 )

 func SayHelloWorld(w http.ResponseWriter, r *http.Request) {
 html := "Hello"
 html = html + " World"
 w.Write([]byte(html))
 }

 func QueryReply(w http.ResponseWriter, r *http.Request) {
 query := r.URL.Query()

 fmt.Println("GET parameters string : ", query)

 first := query.Get("first")
 second := query.Get("second")

 w.Write([]byte("First value : " + first + "\n"))
 w.Write([]byte("Second value : " + second + "\n"))

 // because query is a map, we can use it like a hash table
 // map[first:[1] second:[2]]

 // query by the key "first" example
 firstvalue := query["first"]
 fmt.Println(firstvalue)

 }

 func main() {
 mux := http.NewServeMux()
 mux.HandleFunc("/", SayHelloWorld)
 mux.HandleFunc("/query", QueryReply)

 http.ListenAndServe(":8080", mux)
 }

Pointing your browser to http://localhost:8080/query?first=1&second=2 will produce:

First value : 1

Second value : 2

NOTE : query or r.URL.Query() returns a map, you can retrieve the query value by key.

References :

https://golang.org/pkg/net/url/#URL.Query