Add AR::Base#just_created? to differentiate records

To clarify the benefit of this over writing out the find_or_initialize song and dance mentioned above there are two cases where having a method to check would be better.

1. Where the find_or_create call is internal to a another wrapper method.
2. Where you need to operate on a saved record [most likely needing the id attribute].

1. It includes/passes tests, and works as advertised, and seems to stick with rails conventions. At first I didn't see the usefulness, but I have to admit after trying it out, I can see how it would be helpful. I like it!

Sorry, my post above started with "+1", but formatting seems to have mangled it. +1

Updated patch per Pratik

I'll +1 this as well. I am doing my own find_or_create'ish code in an update (trying to properly handle proper PUT semantics), and need exactly this. I thought rails had new_record_before_save?, but that appears to be part of the association internals.

I like the method name as well.

I'm not sure what the behavior of multiple saves should be:

item = Item.create
item.save
# should just_created? still be true here

I personally could see an argument for either, but I'd think it should be false after the 2nd save. Especially if the object changed between the saves.