i want to check the currently applied layered navigation filters using an observer. When specific filter values are selected an additional layout handle should be added which adds a static block to the content.

For this i created a module which registers on the event controller_action_layout_load_before. In my observer method i call

  $appliedFilters = Mage::getSingleton('catalog/layer')->getState()->getFilters();

But somehow the filter array is always empty, no matter what i tried.

I thought allready of dispatching my own event and passing the filters as an argument, but that might be the dirty way.

Anyone has an idea why i can't access that data? I can access it in the template files.

Thanks a lot for your help!




class My_CustomModule_Model_Observer 
    public function __construct()

    public function checkActiveFilters($observer)
        $layout = $observer->getEvent()->getLayout();
        $appliedFilters = Mage::getSingleton('catalog/layer')->getState()->getFilters();
        foreach($appliedFilters as $filter) {
            Mage::log('Yay! appliedFilters is not empty!');

1 Answer 1


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:

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

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.

  • Yeah! Your answer helped me a lot! I owe you a beer! With your approach i could add a block depending on the filter and its values. My only problem now is that the toHtml method is only called when i load the page, not when i remove or add filters with ajax (i am using the ManaDev SEO Layered Navigation Plus Extension). Any idea how i can make this block being updated as well?
    – phillensen
    Commented Jan 23, 2015 at 10:16
  • I could finally figure it out myself. I had to call <?php echo $this->getChildHtml('foo.bar.category.cmsblock') ?> in the appropriate template file. Now the block is updating according to the applied filters. Thanks again for your help!
    – phillensen
    Commented Jan 23, 2015 at 13:13

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