Workshop 2 - API REST in Go with Gin

In this workshop we will learn how to use the main functions of the Gin package in Go and how to create a REST API.

💡 A quick documentation about REST API.

Step 0: Initialization

All the required information to install the workshop's dependencies are given in the SETUP.md

Step 0.5: The codebase

We designed a boilerplate for this project, it will be useful to start this project, but also to summarize all the required parts of an API We will have :

controllers: this is where you will design your routes endpoint. it will often be a wrapper that calls other API or the database itself
middlewares: those are functions that can be called to print logs ,check access rights before entering a controller or define a default endpoint
routes: the core of the router, setting up all the routes handler, with their middlewares and controllers

There are plenty of other important package you may need in a real API, but these are the main one you can be sure you'll need one time or another. Now let's code.

Add a route on the endpoint /:

It uses the GET method
It responds "hello: world" in a json format

You can test it with http://localhost:8080/ in a browser or with postman

Step 1: Let's get started

You are now fine with the creation of endpoint. Next step is to create different request method. There is many request method, you already experimented the GET request.

For this step, we will use some others' method:

a GET request /item/template: to get the template of the item as follows.

{
  "name": "name",
  "description": "description",
  "price": 0
}

a POST request /item/display: to display the item passed in the body as follows.

also try to implement a default endpoint for the URL's that doesn't match any routes. (404 notfound error)

This tutorial may help you

You should create a structure item with the following fields:

name

description

price

and bind the request body to the structure to retrieve it (do it in a structure folder).

See how to request with postman 📡

Enter your URL and the method you which to use in the title bar and click Send.

Then the result (if there is any) will be printed out at the bottom.

Step 2: Database interaction

For the following we won't use a real database, but we will use a simple json file as the database. (The configuration would have been too long to explain and to do here) You can see the database.json in the database folder.

Create a GET request /item: to retrieve all the items in the database.
Create a POST request /item: to create a new item in the database.