debugging: renderCategoriesMenuHtml returning empty

Question

We have a strange error. When an extension is installed (adds href-lang to head) then menu header is empty (no menu aruments).

Extension on: renderCategoriesMenuHtml returns ""

Extension off: renderCategoriesMenuHtml returns "menu item1; menu item 2 etc"

My conclusion is that $this object might be changed/lost. How can we debug this?

---

** Function called in top.phtml to generate menubar

<?php $_menu = $this->renderCategoriesMenuHtml(0,'level-top') ?>

** File/function in core catalog/block/navigation

public function renderCategoriesMenuHtml($level = 0, $outermostItemClass = '', $childrenWrapClass = '')
{
    $activeCategories = array();
    foreach ($this->getStoreCategories() as $child) {
        if ($child->getIsActive()) {
            $activeCategories[] = $child;
        }
    }
    $activeCategoriesCount = count($activeCategories);
    $hasActiveCategoriesCount = ($activeCategoriesCount > 0);

    if (!$hasActiveCategoriesCount) {
        return 'Goes wrong here when extension is activated';
    }

Part of extension block rewrite: construct ok? extend ok?

class Module_HrefLang_Block_Head extends Mage_Core_Block_Template {

    protected function _construct() {
        parent::_construct();   
    }

    public function getAlternateUrls() {
        return $this->helper('alternatelang')->getAlternateUrls();
    }

}

Answer 1

This question really needs to have the module code, or a link to it, for anyone to answer correctly.

However, I imagine the designers of the extension tested it either with 'flat catalog category' on or with it set to off. Therefore, disable the cache and go to system->config->catalog, find the setting for 'use flat catalog category' and see what is in there.

Ideally you do want to be using the flat catalog category, however, I can see why this has not worked out well with the hreflang tag code you have added. The code in the module needs to load the other views of a given category, and, for reasons I forget, it is not easy to do setStore and load another category 'object' from flat catalog category. I got mine to work eventually with the flat catalog but I had to get deep into Magento internals to get the result I wanted (i.e. with per store seo urls).

For now, disable flat catalog and see if it works. Also try to reindex and make sure that the tables aren't filled with nulls for the flat catalog indexes.