PHP implements simple MVC

Using MVC in PHP is becoming more and more popular, especially in some open source frameworks. MVC is sufficient for most situations, but there are some situations where it is not suitable, such as relatively simple personal blogs. For blogs with only a few hundred articles, using MVC feels a bit too complicated; similarly for blogs with only a few hundred articles, MVC is not suitable for most situations. For portal websites such as Sina, using MVC, a large number of files will be loaded, and the impact on speed is unacceptable. Maple Bamboo Dream introduces the basic principles of MVC and a simple implementation. The following introduction is suitable for PHP development.

MVC in PHP (recommended learning: PHP video tutorial)

MVC[1] is a software architecture in software engineering . From a PHP perspective, MVC is a little different.

Model (model), the realization of program application functions and the realization of program logic. Responsible for data management and data generation in PHP.

View (view), graphical interface logic. Responsible for output in PHP, handling how to call templates and required resource files.

Controller (controller) is responsible for forwarding requests and processing requests. In PHP, the view to be called and the data used are determined based on the request.

Why use MVC

The main function of MVC is to layer and classify code.

The main purpose of MVC is to solve the problem of separating development and design work in Web development, making the work relatively independent.

During this process, we also discovered some other advantages. The directory structure of the website is clearer, the website is easier to maintain and expand, and modules can be reused.

MVC implementation

Request URL

First, agree on the URL when requesting the page, and implement it with the following structure:

localhost/index.php?c=demo&a=index¶m=welcome

If you want to get a more beautiful URL structure, you can optimize it. Since this URL structure optimization has little to do with this article, I will share it later.

As can be seen from the above parameters, the file accessed is index.php, which also contains three parameters: c, a, and param.

MVC Directory Structure

Next, plan the directory structure of MVC as follows:

 /*
 ├─www                       # 网站根目录
 │  ├─controller             # 控制器目录
 │  │  ├─democontroller.php  # demo控制器
 │  ├─model                  # 模型目录
 │  │  ├─model.php           # model模型
 │  ├─view                   # 视图目录
 │  │  ├─index.php           # index视图
 │  ├─index.php              # 入口文件
 */

Controller controller

Add the following code to the controller/democontroller.php file.

 // controller/democontroller.php
 class DemoController
 {
     public function index()
     {
     echo 'hello world';
     }
 }// End of the class DemoController
 // End of file democontroller.php

Only one DemoController class is defined in this file, and it only contains an index method for outputting hello world.

Add the following code to the entry file index.php file.

 //index.php
 require('controller/democontroller.php');
 $controller = new DemoController();
 $controller->index();
 // End of index.php

Use the above agreed URL in the browser to access and see the output hello world. Of course, if the URL you request is not like that, but as shown below, you can get the same output.

localhost/index.php?c=abc

It is found that the parameters in the URL have no effect.

If you use the following URL to access, you can expect that there will be no output.

localhost/controller/democontroller.php

You can see that if you want to access this website and get the correct results, you can currently only access it through index.php, which is why it is called the entry file. Now you can only access the same page regardless of the parameters, so how do you decide to display different results? Or what about calling a different controller?

Improve the entry file

The following uses the parameters in the URL to decide which controller to use.

  //index.php
 // get runtime controller prefix
 $c_str = $_GET['c'];
 // the full name of controller
 $c_name = $c_str.'controller';
 // the path of controller
 $c_path = 'controller/'.$c_name.'.php';
 // get runtime action
 $method = $_GET['a'];
 // load controller file
 require($c_path);
 // instantiate controller
 $controller = new $c_name;
 // run the controller  method
 $controller->$method();
 // End of index.php

Similarly use the above agreed URL in the browser to access and see the output hello world. Comments in the code explain the purpose of each step. Of course, you can call different controllers and their methods by changing the c and a values ​​in the URL parameters to output different results.

ViewView

Only used the controller controller before, and dynamically called different controllers in the entry file index.php. Then joining the view will show the separation.

 // view/index.php
 class Index {
     public function display($output) {
         // ob_start();
         echo $output;
     }
 }
 // End of index.php

The Index method is defined in the index.php file in the view directory, and there is only one display() function, which is responsible for outputting the variables passed to it.

Modify the controller file below.

 // controller/democontroller.php
 class DemoController
 {
     private $data = 'Hello furzoom!';
     public function index()
     {
     //echo 'hello world';
     require('view/index.php');
     $view = new Index();
     $view->display($data);
     }
 }// End of the class DemoController
 // End of file democontroller.php

A data private variable is defined in the controller. The index() method no longer outputs directly, but uses the view object to process the output. At this time, when accessing according to the above agreed URL, you will see the output:

Hello furzoom!

Different view classes can be called according to different requests to display data in different forms. This will increase the role of the view, and designers can design the page only for the view.

Model

The above seems to be very cool, but what kind of content is displayed is directly specified in the controller. I hope the content is also specified by the URL, so Leave the data processing to the model.

 // model/model.php
 class Model {
     private $data = array(
                 'title' => 'Hello furzoom',
                 'welcome' => 'Welcome to furzoom.com',
                 );
     public function getData($key) {
         return $this->data[$key];
     }
 }
 // End of model.php

The view file model.php defines a Model class, which defines a getData() method to return the requested data.

At the same time, modify the entry file index.php as follows:

  //index.php
 // get runtime controller prefix
 $c_str = $_GET['c'];
 // the full name of controller
 $c_name = $c_str.'controller';
 // the path of controller
 $c_path = 'controller/'.$c_name.'.php';
 // get runtime action
 $method = $_GET['a'];
 // get runtime parameter
 $param = $_GET['param'];
 // load controller file
 require($c_path);
 // instantiate controller
 $controller = new $c_name;
 // run the controller  method
 $controller->$method($param);
 // End of index.php

Add a parameter $param and use it as a method call parameter of the controller.

You also need to modify the controller method to obtain different data based on different parameters.

 // controller/democontroller.php
 class DemoController
 {
     // private $data = 'Hello furzoom!';
     function index($param)
     {
     // echo 'hello world';
         require('view/index.php');
     require('model/model.php');
     $model = new Model();
     $view = new Index();
     $data = $model->getData($param);
     $view->display($data);
     }
 }// End of the class DemoController
 // End of file democontroller.php

Contains the required view files and model files, then generates the view and model files, then obtains data through the model object, and then uses the view object to output the obtained data.

此时，在浏览器中使用上面的约定的URL进行访问，将得到输出如下：

Welcome to furzoom.com

至此PHP的MVC模式已经基本介绍完成了，剩余的工作就是根据需要进行添加扩充了，很简单吧！！

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