How to deal with validation errors from DAO layer.

Question

I have been pondering on how to deal with validation errors from DAO layer.
Lets say you have a DAO that can save a car object. A car has a year, make, model, vin and so on. During the save operation of this DAO, it validates the car attributes to see if they pass some business rules. If it does not it throws some validation exception that contains all the validation errors. These validation errors know nothing about jsf or my components it just knows what attributes on the object are invalid and why.
If I just want to show those errors at the top of the page that would be no problem I could just create some FacesMessage objects and add them to the FacesContext messages. But if the DAO layer is telling me that the make attribute is invalid it would be nice to map it to the make field on the screen. I am wondering if any of you have tackled this problem or have some ideas on how to tackle it?
Brian

Answer 1

Let it throw an exception with a self explaining message, then catch it and embed that message in a FacesMessage.
Or let it throw more specific exception types (InvalidCarMakeException extends CarDAOException and so on) and let JSF handle it with own FacesMessage message.