Build a REST API with Deno and Postgres: A Step-by-Step Guide

Unlock the Power of Deno: A Secure and Modular JavaScript Runtime

What is Deno?

Imagine a JavaScript runtime that combines the best of Node.js with added security, modularity, and ease of use. Meet Deno, the brainchild of the Node.js creators, designed to provide a more robust and efficient development experience. Deno’s sandboxed environment ensures secure code execution, while its decentralized module system and TypeScript support make it an attractive choice for developers.

Setting Up a Deno Project

To get started with Deno, you’ll need:

• Your preferred IDE (e.g., VS Code)
• A Postgres server and GUI tool
• Deno installed on your machine (version 1.22.0 recommended)

Deno Project Structure

Create a project folder with the following structure:

• controllers: Handle incoming requests and responses
• db: Hosts SQL creation script and Postgres database connection
• repositories: Manage database operations
• services: Handle business logic and data transformations

Building the Application

Let’s create a simple CRUD API using Deno, JavaScript, and a Postgres database. We’ll use Oak, a middleware framework inspired by Koa, to handle request and response management.

Index.js: The Entry Point

Create an index.js file with the following code:
javascript
import { Application } from 'https://deno.land/x/[email protected]/mod.ts';
const app = new Application();
// Add error handler, controllers, routing system, and start the server

Config.js: Configuration Settings

Create a config.js file with the following code:
javascript
export const config = {
// Database connection settings
};

Routing with Oak

Create a routes.js file with the following code:
javascript
import { Router } from 'https://deno.land/x/[email protected]/mod.ts';
const router = new Router();
// Define routes for CRUD operations

Database and Repository

Create a database.js file with the following code:
javascript
import { Client } from 'https://deno.land/x/[email protected]/mod.ts';
const client = new Client({
// Postgres connection settings
});

Create a beerRepo.js file with the following code:
javascript
import { client } from './database.js';
// Define CRUD operations using client.queryArray()

Services Layer

Create a beerService.js file with the following code:
javascript
import { beerRepo } from './beerRepo.js';
// Define service methods for CRUD operations

Controllers

Create controller files (e.g., getBeers.js, createBeer.js, updateBeer.js, deleteBeer.js) with the following code:
javascript
import { beerService } from './beerService.js';
// Define controller logic for each CRUD operation

Testing the API

Run the Deno project with the following command:

deno run --allow-net --allow-env index.js

Use a tool like Postman to test the API endpoints.

Conclusion

In this article, we’ve explored the basics of Deno and built a simple CRUD API using JavaScript, Deno, and a Postgres database. With Deno’s secure and modular architecture, you can develop efficient and scalable applications with ease.