How to Use Gorilla Mux in Go: Simple Routing Guide

To use gorilla/mux in Go, first import the package, create a new router with mux.NewRouter(), then define routes using methods like HandleFunc. Finally, start the server with http.ListenAndServe passing the router as the handler.

Syntax

The basic syntax to use Gorilla Mux involves creating a router, defining routes, and starting the HTTP server.

• mux.NewRouter(): Creates a new router instance.
• router.HandleFunc(path, handler): Registers a route with a path and a handler function.
• http.ListenAndServe(address, router): Starts the server on the given address using the router to handle requests.

go

package main

import (
	"net/http"
	"github.com/gorilla/mux"
)

func main() {
	router := mux.NewRouter() // Create router
	router.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("Hello, Gorilla Mux!"))
	}) // Define route

	http.ListenAndServe(":8080", router) // Start server
}

Example

This example shows how to create a simple web server with Gorilla Mux that responds to two routes: the home page and a user page with a dynamic parameter.

go

package main

import (
	"fmt"
	"net/http"
	"github.com/gorilla/mux"
)

func homeHandler(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("Welcome to the Home Page!"))
}

func userHandler(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r) // Get route variables
	userID := vars["id"]
	response := fmt.Sprintf("User ID: %s", userID)
	w.Write([]byte(response))
}

func main() {
	router := mux.NewRouter()
	router.HandleFunc("/", homeHandler).Methods("GET")
	router.HandleFunc("/user/{id}", userHandler).Methods("GET")

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

Output

When you visit http://localhost:8080/ you see: Welcome to the Home Page!
When you visit http://localhost:8080/user/123 you see: User ID: 123

Common Pitfalls

Common mistakes when using Gorilla Mux include:

• Not importing github.com/gorilla/mux properly.
• Forgetting to call http.ListenAndServe with the router as the handler.
• Not specifying HTTP methods, which can cause unexpected route matches.
• Incorrectly using route variables without mux.Vars(r).

Always check that your routes are registered before starting the server.

go

package main

import (
	"net/http"
	"github.com/gorilla/mux"
)

func main() {
	router := mux.NewRouter()

	// Wrong: Missing route variable extraction
	router.HandleFunc("/user/{id}", func(w http.ResponseWriter, r *http.Request) {
		// This will not get the id correctly
		w.Write([]byte("User page"))
	}).Methods("GET")

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

// Correct way:
// vars := mux.Vars(r)
// id := vars["id"]
// Use id in response

Quick Reference

Here is a quick summary of Gorilla Mux usage:

Function	Purpose
mux.NewRouter()	Create a new router instance
router.HandleFunc(path, handler)	Register a route with a handler function
router.HandleFunc(path, handler).Methods("GET")	Register a route for specific HTTP methods
mux.Vars(r)	Extract variables from route parameters
http.ListenAndServe(address, router)	Start HTTP server with router

Key Takeaways

Import and create a router with mux.NewRouter() before defining routes.

Use router.HandleFunc to register routes and specify HTTP methods for clarity.

Extract route variables using mux.Vars(r) inside handler functions.

Pass the router to http.ListenAndServe to handle incoming requests.

Check for common mistakes like missing imports or incorrect route variable usage.