Searchresult wrong. Mage::registry('current_layer') not set - magento

Question

We redesign a magento shop. That shop had a very costumized searchresult page.
Now, after the redesign, the search does not work anymore.
I broke down the problem to the List.php (Mage\Catalog\Block\Product\List.php) where the function _getProductCollection() is called to get the results. This function gets a layer $layer = $this->getLayer(); and there is the main difference to the old version:
public function getLayer()
{
$layer = Mage::registry('current_layer');
if ($layer) {
return $layer;
}
return Mage::getSingleton('catalog/layer');
}
In the old version the Mage::registry('current_layer'); is set. In the new version its not set! And when it is not set it returns a new one return Mage::getSingleton('catalog/layer'); with all the products in it.
I can't think any further. How could I find the place where this layer is set in the old version?
What else could I do?

Answer 1

The search layer model is registered by the catalogsearch/layer block, which is usually added to the search page by the catalogsearch.xml layout file :
<catalogsearch_result_index translate="label">
<label>Quick Search Form</label>
<reference name="root">
<action method="setTemplate"><template>page/3columns.phtml</template></action>
</reference>
<reference name="left">
<block type="catalogsearch/layer" name="catalogsearch.leftnav" after="currency" template="catalog/layer/view.phtml"/>
</reference>
<!-- ... -->
</catalogsearch_result_index>
As it has certainly gone missing, you should add it back to your layout.