How to Use Chi Router in Go: Simple Guide with Examples

To use chi router in Go, first import the github.com/go-chi/chi/v5 package, create a new router with chi.NewRouter(), then define routes using methods like Get or Post. Finally, start the HTTP server with http.ListenAndServe passing the router as the handler.

Syntax

The basic syntax to use chi router involves creating a router instance, defining routes, and starting the server.

• chi.NewRouter(): Creates a new router.
• router.Method(path, handler): Defines a route for HTTP methods like GET, POST.
• http.ListenAndServe(address, router): Starts the HTTP server using the router.

go

package main

import (
	"net/http"

	"github.com/go-chi/chi/v5"
)

func main() {
	r := chi.NewRouter() // create router

	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("Hello, Chi!"))
	})

	http.ListenAndServe(":8080", r) // start server
}

Example

This example shows a simple web server using chi that responds to GET requests on the root path and a dynamic user path.

go

package main

import (
	"net/http"
	"github.com/go-chi/chi/v5"
	"fmt"
)

func main() {
	r := chi.NewRouter()

	r.Get("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte("Welcome to Chi Router!"))
	})

	r.Get("/user/{userID}", func(w http.ResponseWriter, r *http.Request) {
		userID := chi.URLParam(r, "userID")
		fmt.Fprintf(w, "User ID: %s", userID)
	})

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

Output

When you visit http://localhost:8080/ you see:
Welcome to Chi Router!

When you visit http://localhost:8080/user/123 you see:
User ID: 123

Common Pitfalls

Common mistakes when using chi router include:

• Not importing the correct chi/v5 package version.
• Forgetting to call http.ListenAndServe with the router as the handler.
• Using incorrect route patterns or forgetting to extract URL parameters with chi.URLParam.
• Not handling errors from ListenAndServe.

go

/* Wrong: Not passing router to ListenAndServe */
http.ListenAndServe(":8080", nil) // This will not use chi router

/* Right: Pass router */
http.ListenAndServe(":8080", r)

Quick Reference

Function	Description
chi.NewRouter()	Creates a new router instance
router.Get(path, handler)	Handles GET requests for the given path
router.Post(path, handler)	Handles POST requests for the given path
chi.URLParam(r, "param")	Extracts URL parameter from request
http.ListenAndServe(addr, handler)	Starts HTTP server with handler

Key Takeaways

Import and use chi/v5 package to create a router with chi.NewRouter().

Define routes using router methods like Get and Post with path and handler.

Use chi.URLParam to get dynamic URL parameters inside handlers.

Pass the router as the handler to http.ListenAndServe to start the server.

Always check for common mistakes like missing router in ListenAndServe or wrong imports.