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AssociationCollection + Optimistic Locking + Save callback break things

#2307

Consider the following models:

class User has_many :posts end

class Comment belongs_to :user

after_save :update_user

def update_user

// do some weird stuff
user.save

end end

In case you have Optimistic locking enabled on User model, the following code fragment will fail:

@user.posts = [@post1, @post2] ... @user.save

This occured on ActiveRecord 2.1.0.

The cause is simple: when @post1 and @post2 get saved, they invoke their :update_user callbacks, but every model uses its own instance of same User model. The optimistic locking counter gets increased in the models and in the DB, but when you try to save your user model, it has an obsolete version.

An alternative fix is to add a callback: :before_add => lambda { |post, user| r.send :user=, o }, but it's kinda dirty hack I think.

Reported by mail2lf (at gmail) · March 21st, 2009 @ 11:40 AM

Activity

mail2lf (at gmail)
Crap, guys, I'm new here, sorry for breaking the code text a bit:

class User has_many :posts end

class Comment belongs_to :user

after_save :update_user

def update_user
```
// do some weird stuff
user.save
```
end end
March 21st, 2009 @ 11:43 AM
mail2lf (at gmail)
- Assigned user set to DHH
March 24th, 2009 @ 05:00 PM

schorsch

I have similar probs with callbacks from related records changing their parents. In my case its an invoice which is to be destroyed. Its attaxched payments have a callback which changes the status of the parent invoice in an after_destroy callback.

when the transaction reaches the invoice its locking version has been increased and the destroy fails.

@@@ruby class Payment

belongs_to :invoice

after_destroy :change_status

def change status #change the invoice unless self.invoice.to_be_destroyed

end



I had to enhance the stale error output in /activerecord/lib/active_record/locking/optimistic.rb to track my probs down

Yes it might be a bad design and i'll try to avoid such things in the future but for now i need a way to figure out if the object referenced in the callback in inside a (destroy) transaction.

I tried setting an instance var @to_be_destroyed but as i just read both objects(invoice / payment.invoice) are no equal. Maybe a thread variable could help or an explicit destroy switch in the db-table? 

Or has anybody another suggestion?

April 16th, 2009 @ 08:43 PM

schorsch
I have similar probs with callbacks from related records changing their parents. In my case its an invoice which is to be destroyed. Its attaxched payments have a callback which changes the status of the parent invoice in an after_destroy callback.

when the transaction reaches the invoice its locking version has been increased and the destroy fails.

class Payment

belongs_to :invoice

after_destroy :change_status

def change status #change the invoice unless self.invoice.to_be_destroyed

end

end

I had to enhance the stale error output in /activerecord/lib/active_record/locking/optimistic.rb to track my probs down

Yes it might be a bad design and i'll try to avoid such things in the future but for now i need a way to figure out if the object referenced in the callback in inside a (destroy) transaction.

I tried setting an instance var @to_be_destroyed but as i just read both objects(invoice / payment.invoice) are no equal. Maybe a thread variable could help or an explicit destroy switch in the db-table?

Or has anybody another suggestion?

.... to dumb for using formatting

April 16th, 2009 @ 08:45 PM
Jeremy Kemper
- Milestone changed from 2.x to 3.x
[bulk edit]

May 4th, 2010 @ 06:48 PM

Neeraj Singh

Milestone changed from 3.x to 2.x
Importance changed from to

I am not able to reproduce this in rails 3.

ActiveRecord::Schema.define(:version => 20100628071959) do
  create_table "brakes", :force => true do |t|
    t.string  "name"
    t.integer "car_id"
  end
  create_table "cars", :force => true do |t|
    t.string  "name"
    t.integer "lock_version", :default => 0
  end
end

class Brake < ActiveRecord::Base
  belongs_to :car
  after_save :update_car
  def update_car
    car.save
  end
end

class Car < ActiveRecord::Base
  has_many :brakes
end

Car.create
Car.first.brakes.create
Car.first.brakes.create
Car.create

Car.last.brakes = [Brake.first, Brake.last]

June 28th, 2010 @ 08:32 AM

Santiago Pastorino
Neeraj can you try this on 2-3-stable?

June 29th, 2010 @ 02:28 AM
Neeraj Singh
works fine on latest 2-3-stable.

June 29th, 2010 @ 02:44 AM
Santiago Pastorino
mail2lf, schorsch: can you try the git versions of rails 3 and 2-3 to see if you can reproduce the problem?.
Thanks.

June 29th, 2010 @ 05:09 AM
Neeraj Singh
- State changed from new to invalid
Closing this ticket. If it could be reproduced then it will be opened.

July 29th, 2010 @ 09:19 PM
Ryan Bigg
- Tag cleared.
Automatic cleanup of spam.

October 9th, 2010 @ 10:04 PM
Jeff Kreeftmeijer
Automatic cleanup of spam.

November 7th, 2010 @ 04:54 PM