I have added custom attribute for Categories section .I want to fetch specific categories only based on custom attribute value in header . I want to modify this code :


$_menu = $this->getHtml('level-top')

I found this method getHtml() , but I am not understanding where to alter query to get specific categories.

  • you need to modify the block file of this. Commented Jan 10, 2017 at 6:57

1 Answer 1



you need to override method _getDefaultCollection in Mage_Catalog_Model_Resource_Category_Tree :

protected function _getDefaultCollection($sorted = false)
    $this->_joinUrlRewriteIntoCollection = true;
    $collection = Mage::getModel('catalog/category')->getCollection();
    /** @var $collection Mage_Catalog_Model_Resource_Category_Collection */
    // your filters here
    $collection = $collection->addAttributeToFilter('attribute_code', 'attribute_value');


More detailed description:

The category tree rendering on frontend starts in app/code/core/Mage/Page/Block/Html/Topmenu.php

when event page_block_html_topmenu_gethtml_before is fired:

public function getHtml($outermostClass = '', $childrenWrapClass = '')
    Mage::dispatchEvent('page_block_html_topmenu_gethtml_before', array(
        'menu' => $this->_menu,
        'block' => $this

This event is listened by observer in Mage_Catalog_Block_Category::addCatalogToTopmenuItems which calls method getStoreCategories of catalog/category helper:

public function addCatalogToTopmenuItems(Varien_Event_Observer $observer)
        Mage::helper('catalog/category')->getStoreCategories(), $observer->getMenu(), $block

Which eventually leads to :

public function getStoreCategories($sorted=false, $asCollection=false, $toLoad=true)
    $storeCategories = $category->getCategories($parent, $recursionLevel, $sorted, $asCollection, $toLoad);

Where getCategories method is lead to Mage_Catalog_Model_Resource_Category_Tree resource model method.

  • Can you please tell me what is the use of page_block_html_topmenu_gethtml_before & page_block_html_topmenu_gethtml_after dispatch event ? & how did u understand that observer is Mage_Catalog_Block_Category::addCatalogToTopmenuItems? Commented Jan 10, 2017 at 7:17
  • page_block_html_topmenu_gethtml_before is used in core to add category elements into a tree and page_block_html_topmenu_gethtml_after for custom purposes, and as far as I know not used in system. considering observer and addCatalogToTopmenuItems method, i looked into a code and when i did not found collection calls in it, i searched config.xml in modules for string page_block_html_topmenu_gethtml_before (I used in phpstorm find in path )
    – Ilja
    Commented Jan 10, 2017 at 8:01
  • & how did you find getCategories belong to Mage_Catalog_Model_Resource_Category_Tree? Commented Jan 10, 2017 at 8:23
  • take a look into Mage_Catalog_Model_Category::getCategories it is calling Mage_Catalog_Model_Resource_Category::getCategories which is calling Mage::getResourceModel('catalog/category_tree')->addCollectionData() which is calling $this->addCollectionData() and from then skipping couple others methods it is calling _getDefaultCollection method
    – Ilja
    Commented Jan 10, 2017 at 8:34
  • Thank you so much!you explained really well.Can I ask you one more question? Commented Jan 10, 2017 at 8:37

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