How do you use Observers?

Daniel Waite wrote:

Clarification: I'm asking how YOU use them, not how TO use them.

I ask because after reading a post over at Pivotal Blabs (a very good blog, btw), it appears the Observer isn't quite meant to do what I thought it was. Example:

class UserObserver

  def before_validation(user)     user.errors.add_to_base("Can't delete.") if user.admin?   end


I would expect the above to halt the saving of the object because it now fails validation. But it doesn't. The record gets saved anyway.

Then I tried...

class UserObserver

  def before_validation(user)     user.admin?   end


Perhaps returning false would halt the process. Not so. In fact, the only way to stop a save inside an observer is to raise an exception:

I ran into exactly the same problem when I first began experimenting with observers: