# Ensuring both objects in a one-to-many association are not saved without the presence of the other **URL:** \ **Category:** Rails\ **Created:** [October 20, 2008, 5:36am UTC](https://www.ruby-forum.com/t/ensuring-both-objects-in-a-one-to-many-association-are-not-saved-without-the-presence-of-the-other/151306 "2008-10-20T05:36:59Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![evan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/54ee81/32.png) [@evan](https://www.ruby-forum.com/u/evan)\ **Post date:** [October 20, 2008, 5:36am UTC](https://www.ruby-forum.com/t/ensuring-both-objects-in-a-one-to-many-association-are-not-saved-without-the-presence-of-the-other/151306/1 "2008-10-20T05:36:59Z")
Hello. I have an object which is related to a second object through has\_many. The second object (obviously) is related to the first through belongs\_to. I want to ensure that neither object is saved to the database without the presence of the other. How can I do this? Thanks. Evan ---
**Author:** ![evan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/54ee81/32.png) [@evan](https://www.ruby-forum.com/u/evan)\ **Post date:** [October 20, 2008, 6:45am UTC](https://www.ruby-forum.com/t/ensuring-both-objects-in-a-one-to-many-association-are-not-saved-without-the-presence-of-the-other/151306/2 "2008-10-20T06:45:59Z")
Evan wrote: > Hello. > > I have an object which is related to a second object through has\_many. > The second object (obviously) is related to the first through > belongs\_to. I want to ensure that neither object is saved to the > database without the presence of the other. How can I do this? > > Thanks. > > Evan Use transaction ---
**Author:** ![evan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/54ee81/32.png) [@evan](https://www.ruby-forum.com/u/evan)\ **Post date:** [October 20, 2008, 7:01am UTC](https://www.ruby-forum.com/t/ensuring-both-objects-in-a-one-to-many-association-are-not-saved-without-the-presence-of-the-other/151306/3 "2008-10-20T07:01:45Z")
Even with transactions can I save the object containing the foreign key without saving the primary object first? In other words, can I save the object that requires the foreign key to be present if I don’t have the foreign key because the primary object has not yet been saved, thus generating an id for it? ---
**Author:** ![evan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/54ee81/32.png) [@evan](https://www.ruby-forum.com/u/evan)\ **Post date:** [October 20, 2008, 7:45am UTC](https://www.ruby-forum.com/t/ensuring-both-objects-in-a-one-to-many-association-are-not-saved-without-the-presence-of-the-other/151306/4 "2008-10-20T07:45:36Z")
I guess the question I was really getting at is how can I validate the presence and association of both objects before they are saved? I feel more confident when there is code in the model itself to ensure the integrity of the data rather than depending on each programmer to place every save in a transaction block. ---
**Author:** ![evan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/54ee81/32.png) [@evan](https://www.ruby-forum.com/u/evan)\ **Post date:** [October 20, 2008, 7:03am UTC](https://www.ruby-forum.com/t/ensuring-both-objects-in-a-one-to-many-association-are-not-saved-without-the-presence-of-the-other/151306/5 "2008-10-20T07:03:31Z")
Oh wait. I think I just got it. Start a transaction, save the primary object thus getting the id, save the secondary object, end transaction. Right? ---
**Author:** ![evan](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/54ee81/32.png) [@evan](https://www.ruby-forum.com/u/evan)\ **Post date:** [October 20, 2008, 11:45am UTC](https://www.ruby-forum.com/t/ensuring-both-objects-in-a-one-to-many-association-are-not-saved-without-the-presence-of-the-other/151306/6 "2008-10-20T11:45:32Z")
[http://api.rubyonrails.org/classes/ActiveRecord/Validations/ClassMethods.html#M001343](http://api.rubyonrails.org/classes/ActiveRecord/Validations/ClassMethods.html#M001343)