How can I pass multiple attributes to find_or_create_by in Rails 3?

I want to use find_or_create_by, but this statement does NOT work. It does not "find" or "create" with the other attributes.

productproperty = ProductProperty.find_or_create_by_product_id(:product_id => product.id, :property_id => property.id, :value => d[descname])

There seems to be very little, or no, information on the use of dynamic finders in Rails 3. "and"-ing these together gives me a an unknown method error.

UPDATE:

Originally I couldn't get the following to work. Please assume I'm not an idiot and "product" is an instance of Product AR model.

product.product_properties.find_or_create_by_property_id_and_value(:property_id => 1, :value => "X")

The error methods was:

no such keys: property_id, value

I couldn't figure that out. Only this morning did I find the reference to passing the values like this instead:

product.product_properties.find_or_create_by_property_id_and_value(1, "X")

And voilá, it works fine. I would have expected a hash to work in the same situation but I guess not.

So I guess you get a down vote if you miss something on the internet?