Magento - get filterable attributes by category

Question

I have created a custom navigation module specifically for a website, but I really want to be able to list filterable attributes by a specific category. So for instance my main

Answer 1

Magento uses the model Catalog_Model_Layer to accomplish this, so I'm guessing this may be your best bet. Caveat emptor, I have not tested this code yet:

$layer = Mage::getModel("catalog/layer");
foreach($categories as $categoryid) {
    $category = Mage::getModel("catalog/category")->load($categoryid);
    $layer->setCurrentCategory($category);
    $attributes = $layer->getFilterableAttributes();
    // do something with your attributes
}

Each iteration here will give you an object of the class Mage_Catalog_Model_Resource_Eav_Mysql4_Attribute_Collection, which you should be able to iterate over in a foreach loop to get your desired output.

For caching, try enabling block caching on your site and give the block a cache tag like the following. Magento will cache the HTML output and all will be right with the world:

protected function _construct() {
    $this->addData(array(
        'cache_lifetime' => 3600,
        'cache_tags'     => array(Mage_Catalog_Model_Product::CACHE_TAG),
        'cache_key'      => $someUniqueIdentifierYouCreate,
    ));
}

The cache will only be valid for the key you pass, so make sure that, if the menu is to change (w/o flushing the cache, for instance), that the cache key is different.

Hope that helps!

Thanks, Joe