Better to pass Activerecord objects or ids as parameters?

Hi all,

I'm wondering what the best practices/conventions are for passing
parameters to models I am writing. Is it better to pass ActiveRecord
objects, or their database IDs?

I personally would pass activerecord objects. Sometimes you might
waste a little if you do just use that object for it's id but I
wouldn't worry about that too much. Apart from anything else doing the
find validates that the id does actually correspond to a real object.
You might consider skipping it for something that's really on the hot
path but I really wouldn't do that from the outset.