adding products compare to magento using products attributes (category)

Question

Hy ,, Im trying to make Magento compare products by grouping all products with the same cateogry and compare them together ,and group the other and compare them together..etc instead of comparing all them togher, I have tried this code

      collection.php

      class Mage_Catalog_Model_Resource_Product_Collection extends   Mage_Catalog_Model_Resource_Collection_Abstract

      public function addCategoryFilterH($request)
      {

        $this->_productLimitationFilters['category_id'] =$request;
        unset($this->_productLimitationFilters['category_is_anchor']);


        $this->_applyZeroStoreProductLimitations();

        $this->_applyProductLimitations();

            return $this;


}

then i do in products compare this :

          list.phtml
          $this_original=$this;
          $cat15=$this->getItems()->addCategoryFilterH(15);
           ...for loop throw this products ....
          $this=$this_original;
          $cat8=$this->getItems()->addCategoryFilterH(8);
          ...for loop throw this products ....
          ...next category id ... 
          ...for loop ... etc 

but my code did not work , any Help?

Answer 1

in collection.php add this function , you don't need to write class name as i did , i wrote it ensure that you are modifying the correct file

  class Mage_Catalog_Model_Resource_Product_Collection extends   Mage_Catalog_Model_Resource_Collection_Abstract

  public function addCategoryFilterH($request)
  {

    $this->_productLimitationFilters['category_id'] =$request;
    unset($this->_productLimitationFilters['category_is_anchor']);


    $this->_applyZeroStoreProductLimitations();

    $this->_applyProductLimitations();

        return $this;

in list.php "app/design/frontend/base/default/template/catalog/product/compare/list.phtml" add this code at the top of you file

<?php
$thiscount=clone $this;
$this1=clone $this;
$comparecats=array();
?>
 <?php foreach($thiscount->getItems() as $_item): ?>
        <?php


$att=$_item->getCategoryIds();
array_push($comparecats,$att[0]);

 ?>
  <?php endforeach;

echo "<br>";

 ?>

<?php

$comparecats = array_unique($comparecats);

$this2= clone $this;

?>

<?php foreach ($comparecats  as $cateid):
unset($this);
$this2=clone $this1;
$this2->getItems()->addCategoryFilterByCategoryId($cateid);
echo "<br>";
?>
.........for loop your products using this ...............