What is a REST API? A Beginner’s Guide for PHP Developers

What is a REST API?

This tutorial we’ll explain What is REST API is, what is important, how it’s works and how PHP developers can build one effectively.

API stance for Application programming interface, it’s use for communicating between two software program. it usefully for developing web apps, build apps, Mobile Apps Request and Operating System. The Google Maps, Twitter and Facebook API are likely examples.

We will use PHP for developing APIs, I like personally cause of it’s ease of use, support multiple Database integrations, RESTful API Support like (GET, POST, PUT, DELETE) and Many other reasons.

Restful architecture allow data to exchanges over HTTP Request using JSON format.

let’s understand the concepts of stateless communication and client-server model.
stateless communication not storing any data request while client-server model client can request for any data and server give them response back.

Key Components of a REST API

Every REST API consists of endpoints that handle different HTTP requests like GET, POST, PUT, DELETE. Let’s understand bit more in below table.

How REST APIs Work in PHP

• Setting Up PHP for API development

If you are localhost install XAMPP and create project directory called API development or if you are on live create directory structure as below:

• Understanding MySQL Database and JSON response format.

REST APIs send data back as JSON response, it’s lightweight and easy to use.

{
    "id": 1,
    "name": "John",
    "email": "john@domain.com", 
    "password" :"12345"
}

• Simple REST API request

Below example, create simple REST API where simply display welcome message using GET Request.

header("Content-Type: application/json");
echo json_encode(["message" => "Welcome to my REST API"]);

Example: Creating a Simple REST API in PHP

Let’s start building simple REST API using PHP that retrieves data from a MySQL database and return data as JSON format.

Create MySQL Table users

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    email VARCHAR(100) NOT NULL UNIQUE,
    password VARCHAR(100) NOT NULL
);

Create Connection config.php file

<?php
$host = "localhost";
$db_name = "new_programmerdesk";
$username = "root";
$password = "";
$conn = new mysqli($host, $username, $password, $db_name);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

Create simple rest api file api.php

<?php
header("Content-Type: application/json");
require 'config.php';

/** 
 * @method GET, POST, PUT, DELETE
 * GET => READ, POST=>INSERT, PUT=>UPDATE, DELETE=>DELETE
 * file_get_contents("php://input"), true) Format data by ROW
 */
 
$method = $_SERVER['REQUEST_METHOD'];

$request = $_GET['request'] ?? '';


switch ($method) {
    case 'GET': 
		$user=!empty($request) ? " WHERE id='".$request."'" : "";
        $sql = "SELECT * FROM users ".$user;
        $result = $conn->query($sql);
        $users = [];
        while ($row = $result->fetch_assoc()) {
            $users[] = $row;
        }
        echo json_encode($users);
        break;

    case 'POST':
        $data = json_decode(file_get_contents("php://input"), true);
        if (!empty($data['name']) && !empty($data['email'])) {
            $stmt = $conn->prepare("INSERT INTO users (name, email) VALUES (?, ?)");
            $stmt->bind_param("ss", $data['name'], $data['email']);
            $stmt->execute();
            echo json_encode(["message" => "User created successfully"]);
        } else {
            echo json_encode(["error" => "Missing name or email"]);
        }
        break;

    case 'PUT': 
        $data = json_decode(file_get_contents("php://input"), true);
        if (!empty($request) && !empty($data['name']) && !empty($data['email'])) {
            $stmt = $conn->prepare("UPDATE users SET name=?, email=? WHERE id=?");
            $stmt->bind_param("ssi", $data['name'], $data['email'], $request);
            $stmt->execute();
            echo json_encode(["message" => "User updated successfully"]);
        } else {
            echo json_encode(["error" => "Missing required parameters"]);
        }
        break;

    case 'DELETE':
        $data = json_decode(file_get_contents("php://input"), true);
        if (!empty($request)) {
            $stmt = $conn->prepare("DELETE FROM users WHERE id=?");
            $stmt->bind_param("i", $request);
            $stmt->execute();
            echo json_encode(["message" => "User deleted successfully"]);
        } else {
            echo json_encode(["error" => "Missing user ID"]);
        }
        break;

    default:
        echo json_encode(["error" => "Invalid request method"]);
}
$conn->close();
?>

Create .htaccess file for user-friendly slug

RewriteEngine On    # Turn on the rewriting engine
RewriteRule ^user$ api.php [NC,L]
RewriteRule ^user/([0-9_-]*)$ api.php?request=$1 [NC,L]

Test REST API using Postman.

• READ : GET (Retrieve all user table data)
  curl -X GET http://localhost/user

• READ : GET (Retrieve single value)
  curl -X GET http://localhost/user/{$id}

• INSERT : POST(Add data in table)
  curl -X POST http://localhost/user

• Update User : PUT
  curl -X POST http://localhost/user/{$id}

• Delete User : DELETE
  curl -X DELETE http://localhost/user/{$id}

Best Practices for Building REST APIs in PHP

Build secure REST API in PHP to use JSON response,

For developing advance level of security, use JWT Authentications or OAuth2. Those mostly use of developing mobile apps request API.

Add validations and implement rate limiting.

Implement Error handling and Optimized Database query for better Performance.

FAQ

header("Content-Type: application/json");
echo json_encode(["message" => "Welcome to my REST API"]);

Conclusion

In this tutorial, we covered :

• What is REST APIs, why that important.
• Key Components of a REST API like GET, POST, PUT, DELETE
• Create Simple REST API using MySQL Database.