Optional Parameter Example

April 30, 2026 · View on GitHub

This project demonstrates how to handle optional parameters in a Go application using the Fiber framework.

Prerequisites

Ensure you have the following installed:

Golang
Fiber package

Setup

Clone the repository:

git clone https://github.com/gofiber/recipes.git
cd recipes/optional-parameter

Install dependencies:
```
go get
```

Running the Application

Start the application:
```
go run main.go
```

Example

Here is an example of how to handle optional parameters in a Fiber application:

package main

import (
    "log"
    "strconv"

    "github.com/gofiber/fiber/v3"
)

func main() {
    // user list
    users := [...]string{"Alice", "Bob", "Charlie", "David"}

    // Fiber instance
    app := fiber.New()

    // Route to profile
    app.Get("/:id?", func(c fiber.Ctx) error {
        id, err := strconv.Atoi(c.Params("id")) // transform id to array index
        if err != nil || id < 0 || id >= len(users) {
            return c.SendStatus(fiber.StatusNotFound) // invalid parameter returns 404
        }
        return c.SendString("Hello, " + users[id] + "!") // custom hello message to user with the id
    })

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

In this example:

The :id? parameter in the route is optional.
If no valid id is provided, a 404 Not Found is returned.
Valid id values (0-3) map to users Alice, Bob, Charlie, and David.

References

Fiber Documentation