Magento filter product collection by multiple categories

Question

Is there an easy way to filter a product collection by multiple categories? To get all items in any of the listed categories? addCategoryFilter doesn\'t seem to

Answer 1

Filter Product Collection using multiple category ids

$all_categories = array('3','13','113');   
$productCollection = Mage::getModel('catalog/product')->getCollection();
$productCollection->joinField('category_id', 'catalog/category_product', 'category_id', 
                    'product_id = entity_id', null, 'left')
                  ->addAttributeToSelect('*')
                  ->addAttributeToFilter('type_id', array('eq' => 'simple'))
                  ->addAttributeToFilter('category_id', array($all_categories));
foreach($productCollection as $product)
{
    echo $product->getId() .$product->getName() . "
";
}

You can remove the condition for product type i.e type_id or modify it as per requirement.