Develop a simple MVC in php

This article introduces the method of developing a simple mvc using php through examples, which serves as a starting point. This article is more suitable for friends who are new to mvc. MVC is actually the abbreviation of the three words Model, Controller and View. The main task of Model is to read data from databases or other file systems in the way we need. View, which is mainly responsible for the page, displays the data to the user in the form of html. Controller is mainly responsible for business logic and allocates requests according to the user's Request. For example, to display the login interface, you need to call the loginAction method of a controller userController to display it.

This article introduces how to use PHP to create a simple MVC structure system.

First create a single point of entry, the bootstrap file index.php, as the only entrance to the entire MVC system. What is a single point of entry? The so-called single point of entry means that there is only one entrance for the entire application, and all implementations are forwarded through this entrance. Why do we need a single point of entry? There are several benefits to having a single point of entry: First, some variables, classes, and methods processed globally by the system can be processed here. For example, you need to perform preliminary filtering of data, you need to simulate session processing, you need to define some global variables, and you even need to register some objects or variables into the register. Second, the program structure is clearer.

include("core/ini.php");
initializer::initialize();
$router = loader::load("router");
dispatcher::dispatch( $router);

This file only has 4 sentences, let’s analyze them sentence by sentence now. include("core/ini.php");

Let’s take a look at core/ini.php

set_include_path(get_include_path() . PATH_SEPARATOR . "core/main");
//set_include_path — Sets the include_path configuration option
function __autoload($object){
 require_once("{$ object}.php");
}

This file first sets include_path, that is, if we want to find included files, we tell the system to search in this directory. In fact, we define the __autoload() method. This method was added in PHP5. When we instantiate a function, if the file does not exist, the file will be automatically loaded. The official explanation is: Many developers writing object-oriented applications create one PHP source file per-class definition. One of the biggest annoyances is having to write a long list of needed includes at the beginning of each script (one for each class).

In PHP 5, this is no longer necessary. You may define an __autoload function which is automatically called in case you are trying to use a class/interface which hasn't been defined yet. By calling this function the scripting engine is given a last chance to load the class before PHP fails with an error.

Let’s look at the following sentence initializer::initialize(); This means calling initialize, a static function of the initializer class. Because we set include_path and defined __autoload in ini.php, the program will automatically search for initializer.php in the core/main directory. The initializer.php file is as follows:

class initializer
{
 public static function initialize() {
 set_include_path(get_include_path().PATH_SEPARATOR . "core/main");
 set_include_path(get_include_path().PATH_SEPARATOR . "core /main/cache");
 set_include_path(get_include_path().PATH_SEPARATOR . "core/helpers");
 set_include_path(get_include_path().PATH_SEPARATOR . "core/libraries");
 set_include_path(get_include_path().PATH_SEPARATOR . "app /controllers");
 set_include_path(get_include_path().PATH_SEPARATOR."app/models");
 set_include_path(get_include_path().PATH_SEPARATOR."app/views");
 //include_once("core/config/config.php ");
 }
}
?>

This function is very simple. It only defines a static function, the initialize function. This function is to set include_path. In this way, if files or __autoload are included in the future, they will be searched in these directories.

OK, let’s continue and look at the third sentence $router = loader::load("router");

This sentence is also very simple, it is the static function load that loads the loader function. Next, let’s loader.php

class loader
{
 private static $loaded = array();
 public static function load($object){
 $valid = array( "library",
 "view",
 "model",
 "helper",
 "router",
 "config",
 "hook",
 "cache",
 "db");
 if (!in_array($object,$valid)){
 throw new Exception("Not a valid object '{$object}' to load");
 }
 if (empty(self::$loaded[$object])){
 self::$loaded[$object] = new $object();
 }
 return self::$loaded[$object];
 }
}

This file is to load objects, because we may enrich this MVC system in the future, There will be components such as model, helper, config, etc. If the loaded component is not within the valid range, we throw an exception. If so, we instantiate an object. In fact, the singleton design pattern is used here. That is to say, this object can actually only be an instantiated object. If it is not instantiated, create one. If it exists, it will not be instantiated.

Okay, because what we want to load now is the router component, let’s take a look at the router.php file. The function of this file is to map URLs and parse URLs. router.php

class router
{
 private $route;
 private $controller;
 private $action;
 private $params;
 public function __construct()
 {
 $path = array_keys($ _GET);
 if (!isset($path[0])){
 if (!empty($default_controller))
 $path[0] = $default_controller;
 else
 $path[0] = "index";
 }
 $route= $path[0];
 $this->route = $route;
 $routeParts = split( "/",$route);
 $this->controller=$routeParts[0] ;
 $this->action=isset($routeParts[1])? $routeParts[1]:"base";
 array_shift($routeParts);
 array_shift($routeParts);
 $this->params= $routeParts;
 }
 public function getAction() {
 if (empty($this->action)) $this->action="main";
 return $this->action;
 }
 public function getController() {
 return $this->controller;
 }
 public function getParams() {
 return $this->params;
 }
}

We can see that first we We get $_GET, the URL of the user's request, and then we parse the Controller, Action, and Params from the URL. For example, our address is http://www.tinoweb.cn/user/profile/id/3 So from the above address, we can get that the controller is user, the action seems to be profile, the parameters are id and 3

OK let’s look at the last sentence, that is dispatcher::dispatch($router);

The meaning of this sentence is very clear, it is to get the result of URL parsing, and then use the dispatcher to distribute the controller and action to respond to the user Okay, let’s take a look at the dispatcher.php file

class dispatcher
{
 public static function dispatch($router)
 {
 global $app;
 ob_start();
 $start = microtime(true);
 $controller = $router->getController();
 $action = $router->getAction();
 $params = $router->getParams();
 $controllerfile = "app/controllers/{$controller }.php";
 if (file_exists($controllerfile)){
 require_once($controllerfile);
 $app = new $controller();
 $app->setParams($params);
 $app-> $action();
 if (isset($start)) echo "
Tota1l time for dispatching is : ".(microtime(true)-$start)." seconds.";
 $output = ob_get_clean();
 echo $output;
 }else{
 throw new Exception("Controller not found");
 }
 }
}

This class is obvious. It gets $router and looks for the controller and action in the file to respond to the user's request. OK, we have a simple MVC structure, that's it. Of course, this is not a complete MVC because it does not involve View and Model. I will add more here when I have time. Let's write a Controller file to test the above system. We create a user.php file under app/controllers/ //user.php

class user
{
 function base()
 {
 }
 public function login()
 {
 echo 'login html page';
 }
 public function register()
 {
 echo 'register html page';
 }
 public function setParams($params){
 var_dump($params);
 }
}

Then, you can enter http:// in the browser localhost/index.php?user/register or http://localhost/index.php?user/login to test.