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Custom 404 Not Found Handler Example

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This example demonstrates how to implement a custom 404 Not Found handler using the Fiber web framework in Go. The purpose of this example is to show how to handle requests to undefined routes gracefully by returning a 404 status code.

Description​

In web applications, it's common to encounter requests to routes that do not exist. Handling these requests properly is important to provide a good user experience and to inform the user that the requested resource is not available. This example sets up a simple Fiber application with a custom 404 handler to manage such cases.

Requirements​

Running the Example​

To run the example, use the following command:

go run main.go

The server will start and listen on localhost:3000.

Example Routes​

  • GET /hello: Returns a simple greeting message.
  • Undefined Routes: Any request to a route not defined will trigger the custom 404 handler.

Custom 404 Handler​

The custom 404 handler is defined to catch all undefined routes and return a 404 status code with a "Not Found" message.

Code Overview​

main.go​

package main

import (
    "log"
    "github.com/gofiber/fiber/v2"
)

func main() {
    // Fiber instance
    app := fiber.New()

    // Routes
    app.Get("/hello", hello)

    // 404 Handler
    app.Use(func(c *fiber.Ctx) error {
        return c.SendStatus(404) // => 404 "Not Found"
    })

    // Start server
    log.Fatal(app.Listen(":3000"))
}

// Handler
func hello(c *fiber.Ctx) error {
    return c.SendString("I made a ☕ for you!")
}

Conclusion​

This example provides a basic setup for handling 404 Not Found errors in a Fiber application. It can be extended and customized further to fit the needs of more complex applications.

References​