Notifier/Observer problem editing Real World Example 1

[dale88]

Hi, i am having problem understanding the wiki developer's api tutorial. i followed the first real world example and it works perfectly fine. what i don't understand is "$this->attach($this, array('NOTIFIER_CART_ADD_CART_END'))" why is that the "$this" is attached to the event and in the real world example 1 is attached in a $_SESSION['class']. can anyone explain to me why. and also i have experimented in the real world example 1. i removed the condition "if ($_SESSION['cart']->show_total() >= $this->freeAmount && !$_SESSION['cart']->in_cart($this->freeProductID) )
{

}" and when i tried to add a product in the cart an error occur. the error is INTERNAL SERVER ERROR 500. can anyone tell me why is that happening it is just a statement why is an error comes up.

[dale88]

Anyone i haven't found a solution to this problem for over a month now

[dale88]

any help would be appreciated

[lat9]

I've seen 500-errors when my changes caused an infinite loop.

[dale88]

i don't think its a looping issue cause i can't find any infinite loop in the code

[Ajeh]

Best I can tell you is the line in the real world is calling the other one ...

You could be addressing a class at the wrong point or something ...

There is not enough information on what you are trying to do here ...

Perhaps later, when wilt or DrByte are free and handy they can help you further on that ...

[dale88]

<?php
/**
 * Observer class used to add a free product to the cart if the user spends more than $x
 *
 */
class freeProduct extends base {
  /**
   * The threshold amount the customer needs to spend.
   * 
   * Note this is defined in the shops base currency, and so works with multi currency shops
   *
   * @var decimal
   */
  var $freeAmount = 50;
  /**
   * The id of the free product.
   * 
   * Note. This must be a true free product. e.g. price = 0 Also make sure that if you don't want the customer
   * to be charged shipping on this, that you have it set correctly.
   *
   * @var integer
   */
  var $freeProductID = 57;
  /**
   * constructor method
   * 
   * Attaches our class to the $_SESSION['cart'] class and watches for 2 notifier events.
   */
  function freeProduct() {
    $_SESSION['cart']->attach($this, array('NOTIFIER_CART_ADD_CART_END', 'NOTIFIER_CART_REMOVE_END'));
  }
  /**
   * Update Method
   * 
   * Called by observed class when any of our notifiable events occur
   *
   * @param object $class
   * @param string $eventID
   */
  function update(&$class, $eventID, $paramsArray = array()) {
  
    if ($eventID == 'NOTIFIER_CART_REMOVE_END' && (isset($_SESSION['freeProductInCart']) && $_SESSION['freeProductInCart'] == TRUE ))
  {
    if (!$_SESSION['cart']->in_cart($this->freeProductID))
    {
      $_SESSION['userRemovedFreeProduct'] = TRUE;
    }
  }

  if (!isset($_SESSION['userRemovedFreeProduct']) || $_SESSION['userRemovedFreeProduct'] != TRUE) 
  {
    if ($_SESSION['cart']->show_total() >= $this->freeAmount && !$_SESSION['cart']->in_cart($this->freeProductID) ) // when this statement is removed i get an error  
    {    
      
      $_SESSION['cart']->add_cart($this->freeProductID);
      $_SESSION['freeProductInCart'] = TRUE;  
    }
  }
 
  if ($_SESSION['cart']->show_total() < $this->freeAmount && $_SESSION['cart']->in_cart($this->freeProductID) ) 
  {
    $_SESSION['cart']->remove($this->freeProductID);
  }

 
  if ($_SESSION['cart']->in_cart($this->freeProductID)) 
  {
    $_SESSION['cart']->contents[$this->freeProductID]['qty'] = 1;
  }
   
  }  
}

?>

thanks man. that is the code on wiki. "if ($_SESSION['cart']->show_total() >= $this->freeAmount && !$_SESSION['cart']->in_cart($this->freeProductID) ) " when that statement is remove i get an error the page wont load properly.

[dale88]

can you tell me what does it mean when I attach an event to a class just like $_SESSION['cart']->attach($this, array('NOTIFIER_CART_ADD_CART_END', 'NOTIFIER_CART_REMOVE_END'));. Is it like I will include that script to that function?? that is why I can't easily use an add_cart method because other function is using that method?

[wilt]

Hi,

When you do

$_SESSION['cart']->attach($this, array('NOTIFIER_CART_ADD_CART_END', 'NOTIFIER_CART_REMOVE_END'));

you are telling the observer/notifier system(ONS) that you want to watch for 2 events 'NOTIFIER_CART_ADD_CART_END', 'NOTIFIER_CART_REMOVE_END'

Whenever those events happen, the ONS will call the update method of the class you passed a reference for($this, which in the example is the freeProduct class)

the update method for the freeProduct class will be called twice. Once when the NOTIFIER_CART_ADD_CART_END happens and again when the 'NOTIFIER_CART_REMOVE_END event happens.

When the update method is called it receives a copy of the class that called it(In the example the $_SESSION['cart'] class, and details of the notifier that caused the event to happen. (ie either NOTIFIER_CART_ADD_CART_END or NOTIFIER_CART_REMOVE_END

HTH

Ian

[dale88]

Thank you very much for the explanation, i kind of get it now how it works.