Golang CRUD REST API with Gin

This is a simple CRUD (Create, Read, Update, Delete) REST API in Go using the Gin web framework.

Before learning about implementation of REST API in Go using GIN, I suggest learn the basics of GO first. Checkout the repository here to learn about the basic implementation in GO.

Getting Started

Follow these instructions to get a copy of the project up and running on your local machine.

Prerequisites

• Go (at least version 1.11)

Cloning the Project

git clone https://github.com/Shikha-code36/golang-crud-rest-api-gin.git
cd golang-crud-rest-api-gin

Initializing the Project

go mod init github.com/Shikha-code36/golang-crud-rest-api-gin

Downloading Dependencies

go mod tidy

Running the Application

go run main.go

The application will start running at http://localhost:8080.

Explanation of Code

main.go

The main.go file is the entry point of our application. Here's a breakdown of its structure and functionality:

package main

This line defines the package that this file belongs to. In Go, the main package is special. It's the entry point of the application, and it must contain a main function.

import (
    "github.com/gin-gonic/gin"
    "github.com/Shikha-code36/golang-crud-rest-api-gin/handlers"
)

This block imports two packages. The first one, github.com/gin-gonic/gin, is the Gin web framework that we're using to build our API. The second one, github.com/Shikha-code36/golang-crud-rest-api-gin/handlers, is the package that contains our handler functions.

func main() {
    r := gin.Default()

This is the main function where our application starts. gin.Default() creates a new Gin engine with some default middleware (logger and recovery). This engine is used to set up our routes and start the server.

    r.GET("/users", handlers.GetUsers)
    r.GET("/user/:id", handlers.GetUser)
    r.POST("/create_user", handlers.CreateUser)
    r.PUT("/update_user/:id", handlers.UpdateUser)
    r.DELETE("/delete_user/:id", handlers.DeleteUser)

These lines define our API routes. For each route, we specify an HTTP method (GET, POST, PUT, DELETE), a path, and a handler function. When a request is received that matches a route's method and path, the corresponding handler function is called.

    r.Run()
}

Finally, r.Run() starts the Gin server and begins listening for requests. By default, it listens on localhost:8080, but you can pass a different address as an argument to Run if you want.

That's the basic structure of our main.go file. It sets up our server, defines our routes, and starts the server.

users.go in handlers

The users.go file in the handlers directory contains the handler functions for our routes. You can find the detailed explanation here.

API Endpoints

• GET /users: Fetch all users.
• GET /user/:id: Fetch a user by ID.
• POST /create_user: Create a new user. The request body should be a JSON object with a name field, like this: {"name": "Alice"}. The ID will be assigned automatically.
• PUT /update_user/:id: Update a user by ID. The request body should be a JSON object with a name field, like this: {"name": "Bob"}.
• DELETE /delete_user/:id: Delete a user by ID.

Testing the API

You can use a tool like curl or Postman to test the API. Here are some examples:

• Fetch all users:

curl -X GET http://localhost:8080/users

• Fetch a user by ID:

curl -X GET http://localhost:8080/user/1

• Create a new user:

curl -X POST -H "Content-Type: application/json" -d '{"name":"Alice"}' http://localhost:8080/create_user

• Update a user by ID:

curl -X PUT -H "Content-Type: application/json" -d '{"name":"Bob"}' http://localhost:8080/update_user/1

• Delete a user by ID:

curl -X DELETE http://localhost:8080/delete_user/1