URLEncoder

How to URL Encode a String in Golang

Rajeev Singh3 mins

How to do URL Encoding in Golang

In this article, you’ll learn how to URL Encode a query string or path segment in Golang. URL Encoding, also known as percent encoding, converts a string containing unprintable, reserved, or non-ASCII characters to a universally accepted format that can be transmitted over the internet.

URL Encoded data is also referred to as application/x-www-form-urlencoded MIME format.

URL Encoding a Query string in Golang

Go’s net/url package contains a built-in method called QueryEscape to escape/encode a string so that it can be safely placed inside a URL query. The following example demonstrates how to encode a query string in Golang -

package main

import (
	"fmt"
	"net/url"
)

func main() {
	query := "Hellö Wörld@Golang"
	fmt.Println(url.QueryEscape(query))
}
# Output
Hell%C3%B6+W%C3%B6rld%40Golang

URL Encoding multiple Query parameters in Golang

If you want to encode multiple query parameters at once, then you can create a url.Values struct consisting of Query param to value mapping and encode all the query params using the url.Values.Encode() method.

Here is an example -

package main

import (
	"fmt"
	"net/url"
)

func main() {
	params := url.Values{}
	params.Add("name", "@Rajeev")
	params.Add("phone", "+919999999999")

	fmt.Println(params.Encode())
}
# Output
name=%40Rajeev&phone=%2B919999999999

URL Encoding a Path Segment in Golang

Just like QueryEscape, the net/url package in Go has another function named PathEscape() to encode a string so that it can be safely placed in the path segment of a URL -

package main

import (
	"fmt"
	"net/url"
)

func main() {
	path := "path with?reserved+characters"
	fmt.Println(url.PathEscape(path))
}
# Output
path%20with%3Freserved+characters

Building a complete URL by encoding individual parts

Finally, Let’s see a complete example of URL parsing and URL encoding in Golang -

package main

import (
	"fmt"
	"net/url"
)

func main() {
	// Let's start with a base url
	baseUrl, err := url.Parse("http://www.mywebsite.com")
	if err != nil {
		fmt.Println("Malformed URL: ", err.Error())
		return
	}

	// Add a Path Segment (Path segment is automatically escaped)
	baseUrl.Path += "path with?reserved characters"

	// Prepare Query Parameters
	params := url.Values{}
	params.Add("q", "Hello World")
	params.Add("u", "@rajeev")

	// Add Query Parameters to the URL
	baseUrl.RawQuery = params.Encode() // Escape Query Parameters

	fmt.Printf("Encoded URL is %q\n", baseUrl.String())
}
# Output
Encoded URL is "http://www.mywebsite.com/path%20with%3Freserved%20characters?q=Hello+World&u=%40rajeev"

Also Read: How to do URL decoding in Golang

References