Question

All,

I am studying some sample code given in my web dev class as an example of MVC (again, for the web). In this code, there’s a system to navigate from the index.php page to the various controllers (which then call the Model and View modules), and then back into index.php.

I understand how the MVC works.

What I’m grappling with is the navigation mechanism. I am having difficulties understanding how all the pieces work together.

Could anyone take a look at the code below and tell me if this matches a well known method / pattern to deal with dynamic website navigation? (Maybe the Front Controller?) If it does, then my hope is that I can more easily do some more research on it.

Many thanks!

JDelage

Index.php

<?php
require_once("User.php");
session_start();

if (isset($_GET['action'])) 
  $action= $_GET['action'];
 else
   $action="";

switch ($action) {
 case 'login':
   require_once('Login.php');
   $command= new LoginControler();
   break;
 case 'logoff':
   require_once('Logoff.php');
   $command= new LogoffControler();
   break;
// Several other cases
 default:
   require_once('Unknown.php');
   $command= new UnknownControle();
}


$command->execute();
require_once('EntryMenu.php'); // Those are objects that represent both the 
// menu label and the links.
$menu= array(
         new EntryMenu("Login", "index.php", array("action" => "logon")),
         new EntryMenu("Logoff", "index.php", array("action" => "logoff")),
         new EntryMenu("Write", "index.php", array("action" => "write")),
         new EntryMenu("Read", "index.php", array("action" => "read"))
);

if ($command->redirect) {
  header('Location: ' . $command->redirect);
 } else if ($command->page) {

  include("ui/header.php");
  include("ui/menu.php");
  echo "<div class='content'>";
  include("ui/". $command->page);
  echo "</div>";
  include("ui/footer.php");
 }
?>

Controler.php

<?php
class Controler {
    public $page= "problem.php";
    function execute() {}
}
?>

LogoffControler.php

<?php
require_once('Controler.php');
class LogoffControler extends Controler {

  function execute() {
    $this->redirect= "index.php";
    unset($_SESSION['user']);
  } 
}
?>

LoginControler.php

<?php
 require_once('LoginModel.php'); // This manages the exchanges with the user db
 require_once('Controler.php');

 class ConnexionControle extends Controler {
  public $page= "LoginForm.php";

  function execute() {

  // More code to deal with incorrectly filled login forms

  $login = new LoginModel();
  $login->loginUser($_POST['login'], $_POST['password']);
  if ($login->userLogedIn()) {
    $_SESSION['user']= $login->user;
    $this->redirect= "index.php";
  }

// More code to deal with invalid logins

 } 
}
?>

Answer 1

I am assuming you understand the controller part, and is asking about the switch..case statements. I haven’t come across an official name for that yet,but most MVC frameworks for PHP (Kohana, CakePHP, CodeIgniter, Fat Free and etc.) calls that ‘routing’. It’s mapping of a URL to a controller.

Using a switch..case sets of statement is one of the easier ways. More sophisticated solutions use RegEx to match pre-defined URL patterns to resolve what controller to invoke, and what are its parameters (usually bundled as a ‘request’)

Other methods include using URL rewriting to come up with pretty urls, such as /articles/month/nov/article-id/3

which in ‘ugly url form’ is :

action=articles&month=nov&article-id=3