# Subset of a model instance's collection

**URL:** <https://www.ruby-forum.com/t/subset-of-a-model-instances-collection/139624>\
**Category:** Rails\
**Created:** [June 5, 2008, 4:18pm UTC](https://www.ruby-forum.com/t/subset-of-a-model-instances-collection/139624 "2008-06-05T16:18:42Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![schof](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/8dc957/32.png) [@schof](https://www.ruby-forum.com/u/schof)\
**Post date:** [June 5, 2008, 4:18pm UTC](https://www.ruby-forum.com/t/subset-of-a-model-instances-collection/139624/1 "2008-06-05T16:18:42Z")

</div>

I need to get a subset of an objects collection. Sort of like  
named\_scope but for a specific model instance.

Foo has\_many :bar  
Bar has\_many :buzz

I want all of the bars for a specific foo but I only want to consider  
bars without buzz.

The best I can come up with is using a “select”

foo.bars.select { |bar| bar.buzzs.empty? }

Is there a better way to do this?

TIA

Sean