Magento 1.7 Filter products by multiple categories

Question

I am looking for a way to filter the products being returned on a category page by the current category AND an optional sub-category. Every solution I have seen so far has b

Answer 1

look here: http://vibrantdrive.com/how-to-filter-magento-products-using-2-or-more-category-filters/

To get products in Category 4 AND category 5

$_productCollection = Mage::getModel('catalog/product')
 ->getCollection()
 ->joinField('category_id', 'catalog/category_product', 'category_id', 'product_id = entity_id', null, 'left')
 ->addAttributeToSelect('*')
 ->addAttributeToFilter('category_id', array(
     array('finset' => '4'),
     array('finset' => '5'))
 )
 ->addAttributeToSort('created_at', 'desc');

To get product in Category 4 OR category 5

$_productCollection = Mage::getModel('catalog/product')
 ->getCollection()
 ->joinField('category_id', 'catalog/category_product', 'category_id', 'product_id = entity_id', null, 'left')
 ->addAttributeToSelect('*')
 ->addAttributeToFilter('category_id', array(
     array('finset' => array('4', '5')),
 )
 ->addAttributeToSort('created_at', 'desc');