#338 √ resolved
Luke Redpath

Invalid has_one association causes parent object save to fail

Reported by Luke Redpath | June 5th, 2008 @ 11:16 AM

This ticket on the old Rails trac supplied a patch that changes the behaviour of has_one; now, if the associated record is invalid, the parent object will not save. This was supposedly to make it consistent with has_many and was introduced in this changeset

I'm am opening this ticket because I consider this a bug and an undocumented feature change and I'm struggling to understand why this was introduced; it has broken part of an application that I'm attempting to upgrade to Rails 2.1 and I have spent the best part of a few hours trying to track this down.

The reason I consider this a bug is because there is already a way of producing this behaviour explicitly using validates_associated. Why, if this can be done manually (when required) is this being done automatically?

The last post in the old Trac ticket demonstrates a catch-22 situation which is what lead to my own test failures. Here is an example that fails as a result of this new behaviour: 

class Snippet
  has_one :wiki_entry
end

class WikiEntry
  belongs_to :snippet
  validates_presence_of :snippet_id <= this is the important bit!
end

s = Snippet.new
s.build_wiki_entry
s.save # => FAIL!

WikiEntry fails validation because it requires a snippet_id. It cannot get a snippet_id until it's parent Snippet has been saved. But we cannot save the parent Snippet because it's child WikIEntry is valid; catch-22.

Comments and changes to this ticket

Please Login or create a free account to add a new comment.

You can update this ticket by sending an email to from your email client. (help)

Create your profile

Help contribute to this project by taking a few moments to create your personal profile. Create your profile »

Source available from github

The Git repository resides at http://github.com/rails

Check out the current development trunk (Edge Rails) with:

git clone git://github.com/rails/rails.git

Creating or reviewing a patch

See the contributor guide.

Creating a feature request

Please don't. If you want a new feature in Rails, you'll have to pull up your sleeves and get busy yourself. Or convince someone else to do it. See the contributor guide on how to get going. But posting them here is just going to lead to ticket root.

Creating a bug report

When creating a bug report, be sure to include as much relevant information as possible. Post the code sample that causes the problem. Preferably, alter the unit tests and show through either changed or added tests how the expected behavior is not occuring.

Security vulnerabilities should be reported via an email to security@rubyonrails.org, do not use trac for reporting security vulnerabilities. All content in trac is publicly available as soon as it is posted.

Then don't get your hopes up. Unless you have a "Code Red, Mission Critical, The World is Coming to an End" kinda bug, you're creating this ticket in the hope that others with the same problem will be able to collaborate with you on solving it. Do not expect that the ticket automatically will see any activity or that others will jump to fix it. Creating a ticket like this is mostly to help yourself start on the path of fixing the problem and for others to sign on to with a "I'm having this problem too".

Shared Ticket Bins

People watching this ticket

Tags