# Question on Model v Observer

**URL:** <https://www.ruby-forum.com/t/question-on-model-v-observer/136260>\
**Category:** Rails\
**Created:** [April 30, 2008, 7:04am UTC](https://www.ruby-forum.com/t/question-on-model-v-observer/136260 "2008-04-30T07:04:22Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jufemaiz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/b2d939/32.png) [@jufemaiz](https://www.ruby-forum.com/u/jufemaiz)\
**Post date:** [April 30, 2008, 7:04am UTC](https://www.ruby-forum.com/t/question-on-model-v-observer/136260/1 "2008-04-30T07:04:22Z")

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I’ll throw this out to people and get your opinions.

Should callbacks when used in the model be used for manipulating that  
model only and use observers to do external model manipulation or are  
the callbacks within the model acceptable for external model  
modification?

I’ve got a rather complex model of the electricity distribution system  
and I need to update “upstream” data (cached information effectively)  
on changes downstream.

Thoughts?

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**Author:** ![jufemaiz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/b2d939/32.png) [@jufemaiz](https://www.ruby-forum.com/u/jufemaiz)\
**Post date:** [April 30, 2008, 4:41pm UTC](https://www.ruby-forum.com/t/question-on-model-v-observer/136260/2 "2008-04-30T16:41:13Z")

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Unless it breaks something I typically just make it a one-liner, to  
make the ‘real’ code less intense.  
-R

On Tue, Apr 29, 2008 at 11:04 PM, jufemaiz: joel courtney

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**Author:** ![jufemaiz](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/b2d939/32.png) [@jufemaiz](https://www.ruby-forum.com/u/jufemaiz)\
**Post date:** [April 30, 2008, 7:11pm UTC](https://www.ruby-forum.com/t/question-on-model-v-observer/136260/3 "2008-04-30T19:11:43Z")

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I like this blog post:

[http://www.robbyonrails.com/articles/2007/04/28/q-a-activerecord-observers-and-you](http://www.robbyonrails.com/articles/2007/04/28/q-a-activerecord-observers-and-you)

Regards,  
Craig