How to determine if any field in a model / nested model changed?

Question

Is there some quick way to find out if any of a model\'s fields or any fields of it\'s nested models (a.k.a. associations) changed?

Answer 1

To see if a ActiveRecord object has changed, you can call:

instance.changed?

To see if a specific attribute was changed, you can do:

instance.attr_changed?

where attr is the attribute you want to check.

To check for if a nested model changed, you can just do:

instance.nested_model.changed?