How to implement MIME-based content type negotiation for language preferences (e.g., Accept-Language) in Go?

To implement MIME-based content type negotiation for language preferences in Go, you can use the net/http package along with the acceptlanguage library.

Here's an example:

Install the acceptlanguage library:

go get github.com/sykora-ondrej/go-accept-language

Import the required packages in your Go code:

import (
	"net/http"
	"strings"
	"github.com/sykora-ondrej/go-accept-language"
)

Create a handler function to handle the HTTP requests:

func myHandler(w http.ResponseWriter, r *http.Request) {
	// Get the "Accept-Language" header from the request
	acceptLanguageHeader := r.Header.Get("Accept-Language")

	// Parse the "Accept-Language" header using the acceptlanguage library
	al := acceptlanguage.Parse(acceptLanguageHeader)

	// Get the user's preferred language from the parsed header
	preferredLanguage := al.Languages[0]

	// Perform content negotiation based on the preferred language
	if strings.HasPrefix(preferredLanguage.Code, "en") {
		// Return English content
		w.Write([]byte("Hello, world!"))
	} else if strings.HasPrefix(preferredLanguage.Code, "fr") {
		// Return French content
		w.Write([]byte("Bonjour, le monde !"))
	} else {
		// Return a default language content
		w.Write([]byte("Hello, world!"))
	}
}

Set up a HTTP server and register the handler function:

func main() {
	http.HandleFunc("/", myHandler)
	http.ListenAndServe(":8080", nil)
}

In the example above, when a client sends a request, the server extracts the "Accept-Language" header from the request and uses the acceptlanguage library to parse it. It then performs content negotiation based on the preferred language and returns the corresponding content.

Note: Make sure to handle any potential errors related to parsing the "Accept-Language" header or performing content negotiation to ensure the correct behavior of your code.