#922 new
2 College Bums

has_many through transaction rollback

Reported by 2 College Bums | August 28th, 2008 @ 04:32 AM | in 2.3

When saving a model that contains a has_many through association, the entire transaction fails to rollback when the validation fails. Specifically xxx_ids= should not modify the association unless all validations pass.

Example: Let's assume we have a Paper model that contains a title attribute and a has_many through relationship with Categories. We validate to ensure a paper has at least one category and the title is not invalid.

If the title is invalid and the categories are empty and an "update_attributes" occurs even after the validation fails, all associations to categories are lost. The title is not updated as expected. Preferably, the association to categories would not be affected unless a save is successful.


a = Paper.first
a.categories # => [#category1, #category2]
a.update_attributes(:category_ids => [], :title => "invalid") # => false
a.categories # => []
a.title # => "invalid"
a.valid? # => false
a.errors.full_messages # => ["title cannot be invalid", "At least one category must be assigned"]
a.reload
a.title # => "Original"
a.categories # => []
a.valid? # => false

There is a quick fix that doesn't completely solve the problem. In the model where the update_attributes occurs we can force a "rollback" using the following code:


  def update_attributes_with_rollback(*args)
    old_category_ids = self.category_ids
    saved_properly = update_attributes_without_rollback(*args)
    self.category_ids = old_category_ids unless saved_properly
    saved_properly
  end
  alias_method_chain :update_attributes, :rollback

Here are some resources which aided us and may help:

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

Repository is at http://github.com/rails/rails

Check out the development master (Edge Rails):

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

Attachments

Tags