Rails 3 advanced queries

In one of my queries I used
.where (:categories => {item_categories {:item_category_id => nil}} for
'item_category_id IS NULL'.
How to write a similar query for 'item_category_id IS NOT NULL' ?

Hi, Rashila

It looks, that the only good solution here is
.where("categories.item_category_id IS NOT NULL")

MaxR