Building Your First API with Go and Gin

Go (or Golang) has become a popular choice for backend development, thanks to its performance, simplicity, and strong concurrency features. In this tutorial, we’ll build a simple REST API using Go and Gin, a fast and minimalistic web framework.

Prerequisites

Before we start, make sure you have Go installed on your machine (version 1.18 or newer).

Step 1: Setting Up the Project

First, create a new directory for your project and initialize a Go module.

mkdir go-gin-api
cd go-gin-api
go mod init example.com/go-gin-api

Next, let’s add Gin as a dependency.

go get -u github.com/gin-gonic/gin

Step 2: Writing the Code

Create a file named main.go and add the following code. We’ll create a simple API with a single endpoint that returns a JSON response.

package main

import (
	"net/http"
	"github.com/gin-gonic/gin"
)

func main() {
	// Initialize a Gin router with default middleware
	router := gin.Default()

	// Define a route for GET /hello
	router.GET("/hello", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{
			"message": "Hello, World from Gin!",
		})
	})

	// Run the server on port 8080
	router.Run(":8080")
}

What’s happening here?

1. We import the necessary packages: net/http for status codes and gin.
2. gin.Default() creates a router with some helpful middleware, like a logger and a recovery mechanism.
3. We define a handler for GET requests to the /hello path.
4. The handler function receives a gin.Context, which carries request details and allows us to write a response.
5. c.JSON() serializes the given gin.H (a shortcut for map[string]interface{}) into a JSON response with a 200 OK status code.
6. router.Run(":8080") starts the HTTP server and makes it listen for requests on port 8080.

Step 3: Running Your API

You can now run your API from the terminal:

go run main.go

You should see output from Gin indicating the server is running. Now, open a new terminal or your web browser and access http://localhost:8080/hello.

You will receive the following JSON response:

{
  "message": "Hello, World from Gin!"
}

Congratulations! You’ve just built and run your first API with Go and Gin. This is just the beginning. From here, you can explore routing parameters, handling different HTTP methods, connecting to a database, and much more.