Codeigniter 5: How to Handle CRUD Operations in a CodeIgniter REST API

CRUD operations (Create, Read, Update, Delete) form the foundation of most APIs. In this guide, we’ll explore how to implement these operations in a CodeIgniter REST API using a sample users table.

Step 1: Prepare Your Database

Create a users table in your database:

CREATE TABLE users (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    email VARCHAR(100) NOT NULL UNIQUE,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

Step 2: Set Up a Model

Create a model to interact with the users table:

1. Navigate to the app/Models directory.
2. Create a new file named UserModel.php.
3. Add the following code:

namespace App\Models;

use CodeIgniter\Model;

class UserModel extends Model {
    protected $table = 'users';
    protected $primaryKey = 'id';
    protected $allowedFields = ['name', 'email'];
    protected $useTimestamps = true;
}

Step 3: Create a Controller

Create a controller to handle API requests:

1. Navigate to the app/Controllers directory.
2. Create a new file named UserController.php.
3. Add the following code:

namespace App\Controllers;

use App\Models\UserModel;
use CodeIgniter\RESTful\ResourceController;

class UserController extends ResourceController {
    protected $modelName = 'App\Models\UserModel';
    protected $format = 'json';

    // Fetch all users
    public function index() {
        $users = $this->model->findAll();
        return $this->respond($users);
    }

    // Fetch a single user by ID
    public function show($id = null) {
        $user = $this->model->find($id);
        if (!$user) {
            return $this->failNotFound('User not found');
        }
        return $this->respond($user);
    }

    // Create a new user
    public function create() {
        $data = $this->request->getPost();
        if (!$this->model->insert($data)) {
            return $this->failValidationErrors($this->model->errors());
        }
        return $this->respondCreated($data, 'User created successfully');
    }

    // Update a user
    public function update($id = null) {
        $data = $this->request->getRawInput();
        if (!$this->model->update($id, $data)) {
            return $this->failNotFound('User not found or data invalid');
        }
        return $this->respondUpdated($data, 'User updated successfully');
    }

    // Delete a user
    public function delete($id = null) {
        if (!$this->model->delete($id)) {
            return $this->failNotFound('User not found');
        }
        return $this->respondDeleted(['id' => $id], 'User deleted successfully');
    }
}

Step 4: Define Routes

Add routes for the CRUD operations in app/Config/Routes.php:

$routes->group('users', function($routes) {
    $routes->get('/', 'UserController::index');
    $routes->get('(:num)', 'UserController::show/$1');
    $routes->post('/', 'UserController::create');
    $routes->put('(:num)', 'UserController::update/$1');
    $routes->delete('(:num)', 'UserController::delete/$1');
});

Step 5: Test Your API

Use a tool like Postman or cURL to test the API:

1. GET /users: Fetch all users.
2. GET /users/{id}: Fetch a specific user by ID.
3. POST /users: Create a new user. Send data like:

   {
       "name": "John Doe",
       "email": "john@example.com"
   }

4. PUT /users/{id}: Update an existing user. Send data like:

   {
       "name": "John Updated",
       "email": "john_updated@example.com"
   }

5. DELETE /users/{id}: Delete a user by ID.

Conclusion

Congratulations! You’ve successfully implemented CRUD operations in a CodeIgniter REST API. These foundational operations are the building blocks for more advanced API features. In the next blog, we’ll discuss authentication and authorization to secure your API.