REST Api Alternate Model Lookups

Hi, I’ve got an Yii REST web service working by creating an ApiController. The following works and loads the Item db record in JSON format by ItemId:

localhost/foodle/index.php/api/items/100000

My question is how do I provide an alternate method for loading an Item record, other than ItemId. For example, I would like to be able to load the Item record by UPC Code. Something like this:

localhost/foodle/index.php/api/items/upc/0018571082004

I tried adding a custom Action function to the ApiController, but I’m missing something as the URL request generates a 404 error: The system is unable to find the requested action “items”.

public function actionUpc()

{

}

Any idea how I can make this work?

Aaron