PHP development: Using CodeIgniter to implement MVC pattern and RESTful API-PHP Tutorial-php.cn

As web applications continue to evolve, it is important to develop applications more quickly and efficiently. And, with the widespread use of RESTful APIs in web applications, it is imperative for developers to understand how to create and implement RESTful APIs. In this article, we will discuss how to implement MVC pattern and RESTful API using CodeIgniter framework.

Introduction to MVC pattern

MVC (Model-View-Controller), that is, model-view-controller, is a common architectural design pattern in object-oriented programming. In the MVC pattern, the application is divided into three parts:

Model - the part that handles data and data logic.
View - The part that handles the user interface and user input.
Controller (Controller) - The part that handles requests and ensures correct responses.

MVC architecture is one of the widely adopted patterns in web application development. It allows developers to split applications into manageable parts and makes development easier.

Introduction to RESTful API pattern

REST (Representational State Transfer), that is, presentation layer state transfer, is a pattern for creating Web services. RESTful API is a common type of web service that uses the HTTP protocol for data transfer and communication.

In the RESTful API pattern, data is represented as resources and accessed as Uniform Resource Identifiers (URIs). Clients can perform operations on data using HTTP verbs (GET, POST, PUT, DELETE). This makes RESTful APIs easy to understand, extensible, easy to develop, and have a higher degree of interoperability.

CodeIgniter Framework

CodeIgniter is a lightweight PHP development framework that is easy to install and use. It is a powerful tool for developing web applications, with rich libraries and tools that allow developers to quickly build complex web applications.

Use CodeIgniter to implement the MVC pattern

The CodeIgniter framework itself is developed based on the MVC pattern. Let’s see how we can use it to implement the MVC pattern.

Model layer

In CodeIgniter, the Model component is responsible for processing data and data logic, and communicating with the database. You can create your own model classes in the application/models directory.

The following is a simple model class example:

<?php
class Users_model extends CI_Model {

   public function __construct() {
      $this->load->database();
   }

   public function get_users() {
      $query = $this->db->get('users');
      return $query->result_array();
   }
}

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The above example code will return all data in the table named users. Use the $this->db->get() method to get data from the database.

View layer

In CodeIgniter, the View component is responsible for handling the user interface, and the view files are stored in the application/views directory. You can create your own view files.

The following is a simple view file example:

<html>
   <head>
      <title>Users List</title>
   </head>
   <body>
      <h1>Users List</h1>
      <table>
         <thead>
            <tr>
               <th>ID</th>
               <th>Name</th>
            </tr>
         </thead>
         <tbody>
            <?php foreach ($users as $item) { ?>
               <tr>
                  <td><?php echo $item['id']; ?></td>
                  <td><?php echo $item['name']; ?></td>
               </tr>
            <?php } ?>
         </tbody>
      </table>
   </body>
</html>

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The above example code will return the data in the custom array $users. Use a foreach loop to iterate through the data and render it into an HTML table.

Controller layer

In CodeIgniter, the Controller component is responsible for processing user requests and calling the appropriate Model and View components based on the request. You can create your own controller classes in the application/controllers directory.

The following is a simple controller class example:

<?php
class Users extends CI_Controller {

   public function __construct() {
      parent::__construct();
      $this->load->model('users_model');
   }

   public function index() {
      $data['users'] = $this->users_model->get_users();
      $this->load->view('users', $data);
   }
}

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In the above example code, when the user accesses the URL, the index method will be called, which returns this data from the Model component and It and the view are rendered into HTML pages in response to user requests.

Use CodeIgniter to implement RESTful API

In CodeIgniter, you can easily create web services using RESTful API. Let’s see how to implement a RESTful API using CodeIgniter.

Installation and Configuration

First, you need to use Composer to install the REST Server library. Add the following code to the composer.json file.

{
    "require": {
        "chriskacerguis/codeigniter-restserver": "^3.1"
    }
}

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Run the following command to install REST Server:

composer install

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Then, you need to enable the REST Server library. In CodeIgniter, use the following statement to enable the REST Server library.

$this->load->library('rest', array(
      'rest_server' => array(
           'server' => 'http://localhost',
           'port' => 80,
           'api_key' => 'YOUR_API_KEY',
           'api_name' => 'YOUR_API_NAME',
           'api_email' => 'YOUR_API_EMAIL',
           'api_description' => 'YOUR_API_DESCRIPTION',
           'api_maintenance' => FALSE
      ),
      'rest_client' => array(),
));

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Implementing a RESTful API

In CodeIgniter, a RESTful API request is defined as a resource name and an HTTP action. Therefore, controllers and methods need to be defined for each resource. These controllers and methods will handle various HTTP actions for the corresponding resources.

The following is an example of defining a user resource unique identifier (URI):

<?php
class Users extends CI_Controller {

   public function __construct() {
      parent::__construct();
      $this->load->model('users_model');
      $this->load->library('form_validation');
   }

   public function index_get() {
      $users = $this->users_model->get_users();
      $this->response($users, 200);
   }

   public function show_get($id) {
      $users = $this->users_model->get_user($id);
      $this->response($users, 200);
   }

   public function create_post() {
      $this->form_validation->set_rules('name', 'Name', 'required');
      $name = $this->input->post('name');

      if ($this->form_validation->run()) {
         $this->users_model->create_user($name);
         $this->response(['User created'], 200);
      } else {
         $this->response([
               'error' => true,
               'message' => validation_errors()
         ], 422);
      }
   }

   public function update_put($id) {
      $this->form_validation->set_rules('name', 'Name', 'required');
      $name = $this->input->put('name');

      if ($this->form_validation->run()) {
         $this->users_model->update_user($id, $name);
         $this->response(['User updated'], 200);
      } else {
         $this->response([
               'error' => true,
               'message' => validation_errors()
         ], 422);
      }
   }

   public function delete_delete($id) {
      $this->users_model->delete_user($id);
      $this->response(['User deleted'], 200);
   }
}

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The above example code will define a resource with the following URI:

GET /users - Get a list of all users.
GET /users/:id - Get individual user information.
POST /users - Create users.
PUT /users/:id - Update user information.
DELETE /users/:id - Delete a user.

Conclusion

In this article, we discussed how to implement MVC pattern and RESTful API using CodeIgniter framework. We explored how to combine the three parts of the CodeIgniter framework (Model, View, and Controller) to create complex web applications. We also introduced RESTful APIs, which can be used to simplify web services development in CodeIgniter. Hopefully these sample codes will help you better understand how to implement the MVC pattern and RESTful API using the CodeIgniter framework.

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