Magento - Set category in layered navigation - magento

Question

Whenever I search a product using the search box, on the left side there is a filter by category. The code that creates this filter is this one:
<dl id="narrow-by-list">
<?php $_filters = $this->getFilters() ?>
<?php foreach ($_filters as $_filter): ?>
<?php if($_filter->getItemsCount()): ?>
<?php if($_filter->getName() != "Category"){ ?>
<dt><?php echo $this->__($_filter->getName()) ?></dt>
<dd>
<?php echo $_filter->getHtml() ?>
</dd>
<?php } endif; ?>
<?php endforeach; ?>
</dl>
This shows only the main category in the filter, and I'd like to show its subcategories. I tried to set another category programmatically with this code:
<?php
$layer = Mage::getSingleton('catalog/layer');
$_categ = Mage::getModel('catalog/category')->load(5);
$layer->setCurrentCategory($_categ);
?>
... but nothing changed. Any thoughts?

Answer 1

When you try to set the other category on the layer singleton from a template, it's too late as all the treatments were already applied.
What you can do is to copy the file app/code/core/Mage/CatalogSearch/Model/Layer.php into app/code/local/Mage/CatalogSearch/Model/ and to add a modified version of the base Mage_Catalog_Model_Layer::getCurrentCategory() method, looking like this :
public function getCurrentCategory()
{
$category = $this->getData('current_category');
if (is_null($category)) {
if ($category = Mage::registry('current_category')) {
$this->setData('current_category', $category);
}
else {
$category = Mage::getModel('catalog/category')->load(5); // Put here the ID of the category you want to use as basis for category filtering
$this->setData('current_category', $category);
}
}
return $category;
}