Dependant layered navigation filters in Magento

Although not the best method, we wrote a quick and easy means to remove layered navigation filters that are dependant on other filters being enabled. This code should really be in the block and popped into an extension - with the attributes administrable via the backend, but for the purposes of this tutorial - we are just going to hardcode it into the template and let you decide how you want to improve it.

1

Open ./app/design/frontend/default/default/template/catalogue/layer/view.phtml

Add

 <?php /*Create filter dependencies*/
 $_activeFilters[] = array();
 $_filters = Mage::getSingleton('Mage_Catalog_Block_Layer_State')->getActiveFilters();
 $_depends = array(
 "fits product" => array("product manufacturer")
 );
foreach ($_filters as $_filter):
$_activeFilters[] = strtolower($_filter->getName());
endforeach; 
?>

just before getStateHtml() ?>

Replace the contents of

<dl id="narrow-by-list"> ... </dl>

with

 <?php $_filters = $this->getFilters() ?>
 <?php foreach ($_filters as $_filter): ?>
 <?php if($_filter->getItemsCount()): ?>
 
 <?php /*Hide filters whose dependencies are not enabled*/
 $_showFilter = true;
 if(isset($_depends[strtolower($_filter->getName())])):
 $_filterDepends = &$_depends[strtolower($_filter->getName())];
 foreach ($_filterDepends as $_filterDepend):
 if (!in_array($_filterDepend,$_activeFilters) && $_showFilter) {
$_showFilter = false;
 }
 endforeach;
 endif; 
 ?> 
 
 <?php if($_showFilter): ?>
 <dt><?php echo $this->__($_filter->getName()) ?></dt>
 <dd>
 <?php echo $_filter->getHtml() ?>
 </dd>
 <?php endif; ?>
 
 <?php endif; ?>
 <?php endforeach; ?>

4

Change $_depends in step 1 to reflect the names of the attributes that have dependencies on each other.
```
 $_depends = array(
 "fits product" => array("product manufacturer")
 );
```
Ie. In our example, we do not want to display fits product until product manufacturer has been filtered.

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