Building APIs with PostgreSQL

1. Introduction

APIs (Application Programming Interfaces) are essential for enabling communication between different software applications. In this lesson, we'll explore how to build robust APIs using PostgreSQL as the database backend.

2. Key Concepts

• **RESTful API**: A style of web service that uses HTTP requests to manage data.
• **CRUD Operations**: Create, Read, Update, Delete - the four basic functions of persistent storage.
• **PostgreSQL**: An open-source relational database system that emphasizes extensibility and SQL compliance.

3. Step-by-Step Guide

3.1 Setting Up PostgreSQL

First, ensure you have PostgreSQL installed. You can download it from the official site and follow the installation instructions.

3.2 Creating a Database

CREATE DATABASE my_api_db;

3.3 Defining a Table

Define a table to store data. For example, a simple users table:

CREATE TABLE users (
                id SERIAL PRIMARY KEY,
                username VARCHAR(50) NOT NULL,
                password VARCHAR(50) NOT NULL
            );

3.4 Building the API

Using a backend framework like Flask or Express, you can create endpoints to interact with your PostgreSQL database. Below is an example in Node.js with Express:

const express = require('express');
const { Pool } = require('pg');
const app = express();
app.use(express.json());

const pool = new Pool({
    user: 'your_user',
    host: 'localhost',
    database: 'my_api_db',
    password: 'your_password',
    port: 5432,
});

app.get('/users', async (req, res) => {
    const result = await pool.query('SELECT * FROM users');
    res.json(result.rows);
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

3.5 Testing the API

Use tools like Postman or Curl to send requests to your API endpoints and validate responses.

4. Best Practices

• Always validate user input to prevent SQL injection.
• Use environment variables for sensitive data like database credentials.
• Implement pagination for large datasets to improve performance.
• Use proper HTTP status codes in API responses.

5. FAQ