Forum: Ruby on Rails Use callbacks to determine model field changes?

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Lee S. (Guest)
on 2009-05-27 18:26
(Received via mailing list)
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?
Benjamin C. (Guest)
on 2009-05-27 18:32
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Take a look at
ActiveRecord::Dirty<http://api.rubyonrails.org/classes/ActiveRecord/Di...
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Benjamin C.
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Craig D. (Guest)
on 2009-05-27 18:32
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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 B.' screencast on the topic:

http://railscasts.com/episodes/109-tracking-attrib...

Regards,
Craig


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Craig D.
Mutually Human Software
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Lee S. (Guest)
on 2009-05-28 22:16
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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)...
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