Building a Powerful JSON API with Golang: Step-by-Step Guide
Table of Contents:
- Introduction
- Choosing a Name for the Project
- Setting up the Project
- Creating the API Server
- Handling Account Operations
5.1. Handling Get Account
5.2. Handling Create Account
5.3. Handling Delete Account
5.4. Handling Transfer
- Writing JSON Output
- Handling HTTP Methods
- Creating Account Structure
- Implementing Database Storage
- Dockerizing the Project
- Conclusion
Introduction
In this tutorial, I will guide You on how to Create a complete JSON API project in Golang. We will be building a bank where we can transfer money, create accounts, and authenticate everything with JSON web tokens. We will also integrate with Postgres as our database and test the project thoroughly. Finally, we will dockerize the project for easy deployment. So, let's get started!
Choosing a Name for the Project
To begin, we need to come up with a suitable name for our project. Let's call it "Go Bank" as it accurately represents the functionality We Are aiming for.
Setting up the Project
First, we need to set up the project and create the necessary files. We will start by creating a Makefile to bootstrap common tasks such as building, running, and testing the project. Next, we will create a main.go
file that will serve as the entry point for our application. We will use VS Code as our editor, but feel free to use any editor you prefer.
Creating the API Server
In this section, we will create the API server and define our handlers. We will start by defining the API server structure, which will include the listening address and database configuration. Then, we will create a function to initialize the API server.
Handling Account Operations
Now, let's focus on handling different account operations such as retrieving, creating, deleting, and transferring money. We will create separate handlers for each operation to keep our code organized and modular.
Handling Get Account
The first operation we will handle is retrieving an account. We will create a handler function handleGetAccount
that takes an HTTP response Writer and request as parameters, and returns an error. We will extract the account ID from the request and fetch the corresponding account from the database. Finally, we will return the account details in JSON format.
Handling Create Account
Next, we will implement the handler for creating an account. The handleCreateAccount
function will take an HTTP response writer and request as parameters, and return an error. We will extract the necessary information from the request body, generate a new account ID, and save the account in the database. We will then return the created account details in JSON format.
Handling Delete Account
In this section, we will handle the deletion of an account. The handleDeleteAccount
function will take an HTTP response writer and request as parameters, and return an error. We will extract the account ID from the request and delete the corresponding account from the database. Finally, we will return a success message in JSON format.
Handling Transfer
The last operation we will handle is transferring money between accounts. The handleTransfer
function will take an HTTP response writer and request as parameters, and return an error. We will extract the necessary information from the request body, validate the accounts and the transfer amount, and update the account balances accordingly. Finally, we will return the updated account details in JSON format.
Writing JSON Output
To simplify the process of writing JSON responses, we will create a Helper function writeJSON
that takes an HTTP response writer, status code, and value as parameters. This function will set the appropriate headers, encode the value into JSON, and write it to the response writer.
Handling HTTP Methods
To handle different HTTP methods for our API endpoints, we will use the Gorilla Mux Package. We will import the package and create a new router. Then, we will define the routes and handlers for each method using the router. Finally, we will start our API server and listen for incoming requests.
Creating Account Structure
To represent an account in our application, we will define an Account
structure with fields for ID, first name, last name, account number, and balance. We will also create a constructor function NewAccount
to create a new account with the given details.
Implementing Database Storage
In order to store and retrieve account data, we will integrate a Postgres database with our API. We will create an interface Storage
that defines the methods for interacting with the database. Then, we will implement this interface using the Postgres driver and connect to the database. Finally, we will update our handlers to use the storage methods for retrieving, creating, deleting, and transferring accounts.
Dockerizing the Project
To make our project easily deployable, we will dockerize it. We will create a Dockerfile and define the necessary steps to build and run our application within a container. This will allow us to HAND over the project to our DevOps team and enjoy margaritas at the beach while they handle the deployment.
Conclusion
In this tutorial, we have learned how to create a complete JSON API project in Golang. We started by setting up the project, defining the API server, and handling account operations. We also wrote JSON output, handled different HTTP methods, and implemented database storage. Finally, we dockerized the project for easy deployment. By following these steps, you can build powerful and scalable APIs using Golang.