# Proper Way to Force Model to be Creation-time Only Member of another

**URL:** <https://www.ruby-forum.com/t/proper-way-to-force-model-to-be-creation-time-only-member-of-another/177215>\
**Category:** Rails\
**Created:** [October 13, 2009, 2:54pm UTC](https://www.ruby-forum.com/t/proper-way-to-force-model-to-be-creation-time-only-member-of-another/177215 "2009-10-13T14:54:52Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ambrice](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/d9b06d/32.png) [@ambrice](https://www.ruby-forum.com/u/ambrice)\
**Post date:** [October 13, 2009, 2:54pm UTC](https://www.ruby-forum.com/t/proper-way-to-force-model-to-be-creation-time-only-member-of-another/177215/1 "2009-10-13T14:54:52Z")

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Hi all,

What is the proper way to do this. I have a Bundle model. And I wish  
for it to be able to have many Products. But I wish that the products  
that a bundle has only be able to be set at the creation time of the  
Bundle. That is once a Bundle is created I should not be able to  
remove or add Products to it.

thanks,  
Aaron