Rails - May 2009 - Use callbacks to determine model field changes?

What''s the best way to examine what fields on a model are changing?
Would you use a callback to do that and how?

I guess the simplest example of this is how lighthouseapp documents
changes that a person makes to a ticket:

Milestone changed from “2.x” to “3.0”

State changed from “new” to “open”

How could I accomplish the same thing?

Take a look at
ActiveRecord::Dirty<http://api.rubyonrails.org/classes/ActiveRecord/Dirty.html>
--
Benjamin Curtis
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On Wed, May 27, 2009 at 7:25 AM, JL Smith
<autiger02-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>
> What''s the best way to examine what fields on a model are
changing?
> Would you use a callback to do that and how?
>
> I guess the simplest example of this is how lighthouseapp documents
> changes that a person makes to a ticket:
>
> Milestone changed from “2.x” to “3.0”
>
> State changed from “new” to “open”
>
> How could I accomplish the same thing?
> >
>
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If you''re on Rails >= 2.1, you can track attribute changes:

http://api.rubyonrails.org/classes/ActiveRecord/Dirty.html

You might also like Ryan Bates'' screencast on the topic:

http://railscasts.com/episodes/109-tracking-attribute-changes

Regards,
Craig


-- 
Craig Demyanovich
Mutually Human Software
http://mutuallyhuman.com

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Thanks for the help guys.

However, I''ve now hit the trap where I need session data in the
observer (who is changing the model)...