# Validating the presence of two associated objects from both models **URL:** \ **Category:** Rails\ **Created:** [December 31, 2009, 12:31am UTC](https://www.ruby-forum.com/t/validating-the-presence-of-two-associated-objects-from-both-models/180887 "2009-12-31T00:31:32Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![evanchaney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/58f4c7/32.png) [@evanchaney](https://www.ruby-forum.com/u/evanchaney)\ **Post date:** [December 31, 2009, 12:31am UTC](https://www.ruby-forum.com/t/validating-the-presence-of-two-associated-objects-from-both-models/180887/1 "2009-12-31T00:31:32Z")
I have a model “Conversation” and a model “Leader”. A Conversation is always led by exactly 1 Leader. I’ve overridden Conversation’s “validate” method to validate the presence of an associated Leader model. If I add a similar validation to the Leader model, however, Conversations can no longer be saved on creation because the Leader model is invalid. On creation of both a new Conversation and new Leader how can I validate in each model that it is associated with the other? Is there a best practice? The closest I’ve come is to override Leader’s “validate\_on\_update” method to ensure the presence of a Conversation but that still allows new Leader objects to be created without a Conversation, filling my tables with junk. – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Talk” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). ---
**Author:** ![evanchaney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/58f4c7/32.png) [@evanchaney](https://www.ruby-forum.com/u/evanchaney)\ **Post date:** [December 31, 2009, 12:40am UTC](https://www.ruby-forum.com/t/validating-the-presence-of-two-associated-objects-from-both-models/180887/2 "2009-12-31T00:40:54Z")
How about this: class Conversation \< ActiveRecord::Base validates\_presence\_of :leader end That way you can’t save a conversation without assigning it a leader, but the leader doesn’t have to be saved yet. On Dec 30, 3:30 pm, Evan C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I have a model “Conversation” and a model “Leader”. A Conversation is always led by exactly 1 Leader. > > I’ve overridden Conversation’s “validate” method to validate the presence of an associated Leader model. > > If I add a similar validation to the Leader model, however, Conversations can no longer be saved on creation because the Leader model is invalid. > > On creation of both a new Conversation and new Leader how can I validate in each model that it is associated with the other? Is there a best practice? The closest I’ve come is to override Leader’s “validate\_on\_update” method to ensure the presence of a Conversation but that still allows new Leader objects to be created without a Conversation, filling my tables with junk. – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Talk” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). ---
**Author:** ![evanchaney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/58f4c7/32.png) [@evanchaney](https://www.ruby-forum.com/u/evanchaney)\ **Post date:** [December 31, 2009, 12:52am UTC](https://www.ruby-forum.com/t/validating-the-presence-of-two-associated-objects-from-both-models/180887/3 "2009-12-31T00:52:37Z")
> That way you can’t save a conversation without assigning it a leader, > but the leader doesn’t have to be saved yet. Well, that’s where I’m at right now. I’d like to be in a situation where Conversation validates that it has a Leader and Leader validates it has a Conversation before either is saved. – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Talk” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). ---
**Author:** ![evanchaney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/58f4c7/32.png) [@evanchaney](https://www.ruby-forum.com/u/evanchaney)\ **Post date:** [December 31, 2009, 1:04am UTC](https://www.ruby-forum.com/t/validating-the-presence-of-two-associated-objects-from-both-models/180887/4 "2009-12-31T01:04:19Z")
Evan, Don’t overdo your requirements. Take your requirements lightly. From what I can see in your example, Leader plays a larger role in your domain, so it has priority over the Conversation. I would model Leader having zero or more (0…\*) Conversations, Conversation having 1 Leader. A simple one to many relationship between those domain objects. As from what I can tell, your are trying to create both at the same time in the view, thus sending both objects over to the controller. While creating a Conversation, you could give the user the opportunity to create a Leader, if its currently not available, or he wants to get a new one. You could use AJAX to access the create action in the leader controller having it available prior to saving the Conversation. Check out this resource by Ryan B… > **[\#57 Create Model Through Text Field - RailsCasts](http://railscasts.com/episodes/57-create-model-through-text-field)** > > Short Ruby on Rails screencasts containing tips, tricks and tutorials. Great for both novice and experienced web developers. Regards, Rodrigo D. IBM - IGF Project Manager “Communication is the key” On Wed, Dec 30, 2009 at 8:50 PM, Evan C. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > “Ruby on Rails: Talk” group. > To post to this group, send email to removed\_email\_address@domain.invalid. > To unsubscribe from this group, send email to > removed\_email\_address@domain.invalid[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > . > For more options, visit this group at > [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). – You received this message because you are subscribed to the Google Groups “Ruby on Rails: Talk” group. To post to this group, send email to removed\_email\_address@domain.invalid. To unsubscribe from this group, send email to removed\_email\_address@domain.invalid. For more options, visit this group at [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). ---
**Author:** ![evanchaney](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/e/58f4c7/32.png) [@evanchaney](https://www.ruby-forum.com/u/evanchaney)\ **Post date:** [December 31, 2009, 6:41am UTC](https://www.ruby-forum.com/t/validating-the-presence-of-two-associated-objects-from-both-models/180887/5 "2009-12-31T06:41:55Z")
Evan C. wrote: > > That way you can’t save a conversation without assigning it a leader, > > but the leader doesn’t have to be saved yet. > > Well, that�s where I�m at right now. I�d like to be in a situation where > Conversation validates that it has a Leader and Leader validates it has > a Conversation before either is saved. Just validate that there are keys: Conversation validates\_presence\_of :leader, Leader validates\_presence\_of :conversation (perhaps). Do the rest with foreign key constraints in the DB. As you’ve discovered, the application layer is the wrong place for this sort of simple integrity check. > – > > You received this message because you are subscribed to the Google > Groups “Ruby on Rails: Talk” group. > To post to this group, send email to removed\_email\_address@domain.invalid. > To unsubscribe from this group, send email to > removed\_email\_address@domain.invalid. > For more options, visit this group at > [http://groups.google.com/group/rubyonrails-talk?hl=en](http://groups.google.com/group/rubyonrails-talk?hl=en). ## Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid