With the development of mobile Internet, instant messaging has become more and more important and popular. For many companies, live chat is more like a communication service, providing a convenient communication method that can quickly and effectively solve business problems. Based on this, this article will introduce how to use the PHP framework CodeIgniter to develop a real-time chat application.

1. Understand the CodeIgniter framework

CodeIgniter is a lightweight PHP framework that provides a series of simple tools and libraries to help developers quickly develop better app. Its advantages include:

• Simple and easy to use, low entry barrier
• Provides rich libraries and tools, high development efficiency
• Has many community supports and excellent Document
• Very flexible, very suitable for small applications and simple projects

2. Developing real-time chat applications

2.1 Environment configuration

Before running our application, we first need to install the CodeIgniter framework. You can use Composer to install CodeIgniter, a PHP dependency management tool.

Go into your project folder and install CodeIgniter:

composer require codeigniter/framework

After successful installation, use the following command to quickly start a local server:

php -S localhost:8000

This will start a Local server, listening on port 8000. You can access your application by typing localhost:8000 in your browser.

2.2 Establishing a database

The real-time chat application needs to create a database to store chat records and user information. Create a database named "chat" in phpMyAdmin or other database interface, and create the following two tables:

• users: stores the user's basic information, such as username and password
• messages: Store chat records

The following is the structure of the table:

users:

CREATE TABLE `users` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(255) NOT NULL,
`password` varchar(255) NOT NULL,
`created_at` datetime NOT NULL,
`updated_at` datetime NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=16 DEFAULT CHARSET=utf8;

messages:

CREATE TABLE `messages` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`sender_id` int(11) NOT NULL,
`receiver_id` int(11) NOT NULL,
`message` text NOT NULL,
`created_at` datetime NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=22 DEFAULT CHARSET=utf8;

2.3 Implement user registration and Login function

In CodeIgniter, you can use CodeIgniter's default database connection library CI_DB_driver, which can be instantiated simply through the constructor.

Add database configuration in the application's config.php file:

$config['hostname'] = 'localhost';
$config['username'] = 'root';
$config['password'] = 'root';
$config['database'] = 'chat';
$config['dbdriver'] = 'mysqli';
$config['dbprefix'] = '';
$config['pconnect'] = FALSE;
$config['db_debug'] = TRUE;
$config['cache_on'] = FALSE;
$config['cachedir'] = '';
$config['char_set'] = 'utf8';
$config['dbcollat'] = 'utf8_general_ci';
$config['swap_pre'] = '';
$config['encrypt'] = FALSE;
$config['compress'] = FALSE;
$config['stricton'] = FALSE;
$config['failover'] = array();
$config['save_queries'] = TRUE;

Next, we need to define a User Model to handle user registration and login. Create a file named User_model.php in the application/models folder. The code is as follows:

<?php defined('BASEPATH') OR exit('No direct script access allowed');

class User_model extends CI_Model
{
  public function register($data)
  {
    $this->db->insert('users', $data);
  }

  public function login($username, $password)
  {
    $this->db->select('*');
    $this->db->from('users');
    $this->db->where('username', $username);
    $this->db->where('password', $password);
    $query = $this->db->get();
    return $query->row_array();
  }
}

The above code defines two methods: register() method and login() method. The register() method is used to insert user data into the users table, and the login() method is used to obtain user data from the database.

2.4 Implementing the real-time chat function

Create a file named chat.php in the views folder of the application. This page contains two parts: chat interface and input box.

First, we need to get the chat records from the server through Ajax. When a user is logged in, we will always display the latest chat history. Get the latest chat history through the following code:

function getMessages() {
    $.ajax({
        url: '/chat/getMessages',
        type: 'POST',
        dataType: 'json',
        success: function(data) {
            // 將聊天記錄插入到聊天界面
        }
    });
}

setInterval(function() {
    getMessages();
}, 1000);

The above code uses jQuery's Ajax to request the getMessages() method on the server. The setInterval() method sets the timer to trigger the getMessages() method every second.

Next, we need to implement the logic of sending messages. After the user enters the message, they can press Enter or click the Send button to send the message. We need to get the message from the input box and send it to the server via Ajax:

function sendMessage() {
    var message = $('#message').val();
    $('#message').val('');
    $.ajax({
        url: '/chat/sendMessage',
        type: 'POST',
        data: {message: message},
        success: function(data) {
            // 消息已發(fā)送
        }
    });
}

$('#send').click(function() {
    sendMessage();
});

$('#message').keydown(function(event) {
    if (event.keyCode == 13) {
        sendMessage();
    }
});

sendMessage() method gets the message from the input box and sends it to the server. This method can be triggered by clicking the send button or pressing the Enter key.

Next, we need to implement the getMessages() method and sendMessage() method in the Chat controller. Create a file named Chat.php in the application/controllers folder. The code is as follows:

<?php defined('BASEPATH') OR exit('No direct script access allowed');

class Chat extends CI_Controller
{
    public function __construct()
    {
        parent::__construct();
        $this->load->model('message_model');
    }

    public function index()
    {
        // 顯示 頁面
    }

    public function getMessages()
    {
        $data = $this->message_model->get();
        header('Content-Type: application/json');
        echo json_encode($data);
    }

    public function sendMessage()
    {
        $message = $this->input->post('message');
        $this->message_model->send($message);
    }
}

The above code defines 3 methods: index() method, getMessages() method and sendMessage() method. The index() method is used to display the chat.php page, the getMessages() method is used to obtain the latest chat records from the database, and the sendMessage() method receives messages from the client and stores them in the database.

2.5 Implementing the user list

We need to create a file named users.php in the views folder of the application. This page consists of a list showing users who are online. We need to use Ajax to get the list of online users from the server:

function getUsers() {
    $.ajax({
        url: '/chat/getUsers',
        type: 'POST',
        dataType: 'json',
        success: function(data) {
            // 將在線用戶列表插入到列表中
        }
    });
}

setInterval(function() {
    getUsers();
}, 2000);

The above code uses jQuery's Ajax to request the getUsers() method on the server. The setInterval() method sets the timer to trigger the getUsers() method every 2 seconds.

Next, we need to implement the getUsers() method in the Chat controller. This method will return the list of online users:

public function getUsers()
{
    $data = $this->message_model->getUsers();
    header('Content-Type: application/json');
    echo json_encode($data);
}

2.6 Complete the application

Finally, we need to add the login() method and register() method in the Index controller. The login() method is used to display the login page, and the register() method is used to display the registration page. The registration and login pages are simple HTML forms.

After completing the above steps, we developed a real-time chat application using the PHP framework CodeIgniter. Users can log in by entering their username and password, send messages and chat with online users.

3. Summary

This article introduces how to use the PHP framework CodeIgniter to develop a real-time chat application. Features of the app include user registration and login, live chat, online user list, etc. CodeIgniter is a framework that is very suitable for small and medium-sized applications. It provides a series of simple but powerful tools and libraries that can help developers quickly build web applications. Furthermore, there are many aspects to consider during the development of a live chat application. If you are developing a similar application, we recommend that you adopt the approach described in this article and adapt it accordingly to your needs.

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