Magento 1.9 – How to Get Active Filters in catalog/layer/view.phtml

You need to change reference block of product_type_data

• from: product.info
• to: product.info.options.wrapper / product_options_wrapper

Just like

   <PRODUCT_TYPE_grouped translate="label" module="catalog">
            <label>Catalog Product View (Grouped)</label>
            <reference name="product_options_wrapper"> 
<!--  product.info  to product_options_wrapper --> 

The event you are observing (controller_action_layout_load_before) is dispatched before layer filters are initialized. That's why you always get empty array when you call Mage::getSingleton('catalog/layer')->getState()->getFilters();.

In fact, I think there is no suitable single event in Magento for what you're trying to do (add custom layout update handle and get all applied filters).

I would like to suggest an alternative approach but I don't know if it will suit you.

Add following layout update via local.xml file:

<catalog_category_layered>
    <reference name="content">
        <block type="foo_bar/category" name="foo.bar.category.cmsblock" before="-"/>
    </reference>
</catalog_category_layered>

And create a block which extends from Mage_Cms_Block_Block class.

class Foo_Bar_Block_Category extends Mage_Cms_Block_Block
{
    protected function _toHtml()
    {
        $filters = array();
        $appliedFilters = Mage::getSingleton('catalog/layer')->getState()->getFilters();
        foreach($appliedFilters as $filter) {
            $filters[] = $filter->getFilter()->getRequestVar();
        }

        if (!empty($filters)) {
            $this->setBlockId(implode('_', $filters));
        }

        return parent::_toHtml();
    }
}

As you can see it's pretty simple. Line $this->setBlockId(implode('_', $filters)); sets the static block identifier and if the given block exists it will be loaded on your category pages.

Hope this helps.