Category Specific Layered Navigation Changes (Disabling Attribute Filters) [closed]

Question

I'm trying to disable a particular attribute filter in layered navigation for a specific category. The attribute filter I wish to disable is the manufacturer in this instance.

I'm trying the following in the 'Custom Design Layout' for the category in question:-

<block type="catalog/layer_view" name="catalog.leftnav" after="currency" template="catalog/layer/view.phtml">
    <action method="unsetChild"><alias>manufacturer_filter</alias></action>
</block>

This is half working, it hides the manufacturer filter in the layered navigation, but it also hides everything else below this in catalog.leftnav.

Any idea how the above needs modifying to prevent that from happening?

To explain what I mean, here are screenshots.

Before the XML update

After the XML update

Answer 1

You can achieve this if you rewrite the Mage_Catalog_Model_Layer::getFilterableAttributes method.
For a specific category you can add a new filter.

Something like this (not tested)

public function getFilterableAttributes()
{
    $setIds = $this->_getSetIds();
    if (!$setIds) {
        return array();
    }
    $collection = Mage::getResourceModel('catalog/product_attribute_collection');
    $collection
        ->setItemObjectClass('catalog/resource_eav_attribute')
        ->setAttributeSetFilter($setIds)
        ->addStoreLabel(Mage::app()->getStore()->getId())
        ->setOrder('position', 'ASC');
    if ($this->getCurrentCategory()->getId() == 7) {
         //if in that specific category...You can even make this a category setting or a config setting so you won't hard code it.  
         $collection->addFieldToFilter('attribute_code', array('neq'=>'manufacturer'));
    }

    $collection = $this->_prepareAttributeCollection($collection);
    $collection->load();

    return $collection;
}