after_commit :my_callback, :on => :create fires on update too

[basvk]

After upgrading from 4.0.0.beta1 to 4.1.0.rc2 my after_commit hooks are now getting triggered on update too, despite the :on => :create option.

[rafaelfranca]

@basvk could you check with 4.0.4?

[basvk]

Checked with Rails 4.0.4: I can confirm this happens in 4.0.4 as well.

I also realized that I'm actually updating the record inside the after_commit callback... (setting a status when the after_commit task was successful).

[rafaelfranca]

Could you create a gist reproducing the issue. You can found a template in the contributing guide.

[basvk]

Sure, here: https://gist.github.com/basvk/9807527

[laurocaetano]

Hi @basvk, I think your gist is not doing what you have described in this issue. Could you check this one to see if it is correct?

[basvk]

@laurocaetano The issue apparently is caused by doing an update (at the db level) of the record inside the after_commit callback.
In my gist, I trigger that by means of the increment! call.
This was working fine in 4.0.0.beta1 and older, but stopped functioning after that.
(In real life, the business logic behind updating the record is much more complex than this particular example of course).

In your gist, you are not saving the updated attribute inside the after_commit, and the issue does not get triggered. Actually the updated attribute does not get persisted until the post.save line, so in real life the change to the attribute would actually be lost.

So as it is currently, it is not possible to update the record in an after_commit callback without getting into an infinite loop, despite the :on => :create...

[basvk]

BTW here is a real life example:

"After committing the new record to the db, a report file should be automatically created, and the url to the newly created report should be saved in that changed record."

[laurocaetano]

Hi @basvk. You are right.

See: 9d2146a. As you can see in the revert message, the fix introduced a bug and the behavior now is the same as 3.2.

It means this is a bug since 3.2. Also, I think this issue is similar to #8937, could you confirm?

[basvk]

#8937 sure looks related from the description, but I have no way to confirm for sure. I guess it is all connected to each other anyway.

I can only confirm that the issue described in this ticket did not occur in 4.0.0.beta1, I had it in production for a couple of months without problems.

[basvk]

The revert indeed fixes the issue for me, thanks.

[laurocaetano]

I think there is no easy way to make this work 😿

Correct me if I'm wrong, but when the after_commit callback is called the transaction is already finished. If you call save inside the callback, it will trigger another callback again and again and again.

The easy way to have this working, could be something like this:

class User
  after_commit :do_after_commit, on: :create

  def do_after_commit
    name = 'New name'
  end
end

user = User.create! # triggers the `after_commit` callback.

user.save # does the update here.

[abacha]

+1