PHP - What is wrong? Learning MVC - Beginner - php

Question

Hy,
i started learning PHP and i created a simple MVC Style Codebase.
The Script just generates a random number and displays this numer. I also write a function to display the number shown before but it does not work. The value is empty. Can you help me out, i have no clue whats wrong and there is no php error thrown.
view.php
<?php
class View
{
private $model;
private $view;
public function __construct()
{
$this->model = new Model();
}
public function output()
{
echo 'Current Entry: ';
echo $this->model->getData();
echo '<br />';
echo 'Update';
echo '<br />';
echo 'Last';
}
public function getModel()
{
return $this->model;
}
}
controller.php
<?php
class Controller
{
private $model;
private $view;
public function __construct($view)
{
$this->view = $view;
$this->model = $this->view->getModel();
}
public function get($request)
{
if (isset($request['action']))
{
if ($request['action'] === 'update')
{
for ($i = 0; $i<6; $i++)
{
$a .= mt_rand(0,9);
}
$this->model->setData($a);
}
elseif ($request['action'] === 'preview')
{
$this->model->setLast();
}
else
{
$this->model->setData('Wrong Action');
}
}
else
{
$this->model->setData('Bad Request');
}
}
}
model.php
<?php
class Model
{
private $data;
private $last;
public function __construct()
{
$this->data = 'Default';
}
public function setData($set)
{
if ( ! (($set == 'Wrong Action') && ($set == 'Bad Request')))
{
$this->last = $this->data;
}
$this->data = $set;
}
public function getData()
{
return $this->data;
}
public function setLast()
{
$this->data = $this->last;
}
public function getLast()
{
return $this->last;
}
}
index.php
<?php
require_once 'controller.php';
require_once 'view.php';
require_once 'model.php';
$view = new View();
$controller = new Controller($view);
if (isset($_GET) && !empty($_GET)) {
$controller->get($_GET);
}
$view->output();
Are there any other, bad mistakes in the Script?
Any input very welcome! :)

Answer 1

The problem with your code is that PHP does not preserve variable values between requests, therefore, when you set your $model->last value here:
$this->last = $this->data;
It gets reset on your next request.
You may want to store $last value in a session or a cookie instead. Something like:
$_SESSION['last'] = $this->data;
And then when you are instantiating your model you could initialize it with a value stored in a session if available:
index.php - add session_start() at the beginning
model.php:
public function __construct()
{
$this->data = isset($_SESSION['last']) ? $_SESSION['last'] : 'Default';
}
public function setData($set)
{
$this->data = $set;
if ( ! (($set == 'Wrong Action') && ($set == 'Bad Request')))
{
$_SESSION['last'] = $this->data;
}
}
controller.php
elseif ($request['action'] === 'preview')
{
//Remove this
//$this->model->setLast();
}