Forum: Rails-core (closed, excessive spam) Inconsistent before_create behavior

Hello.

1. When before_create returns false:
a) active transaction is COMMITED if it was called from  model.save
b) active transaction is ROLLED BACK if it was called from model.save!

Is it intended ? If yes, how to dynamically determine if before_create
semantics - ie. whether it commits or rollbacks on fail (as it depends
on how it was called) ?

2. I create some models in before_create callback. In this process
something my fail. Is it possible to  ROLLBACK the transaction even if
it was invoked by save ?

I tried:

a) wrapping operations on model in Model.transaction do ... end- does
not work as transactions cannot be nested.

b) raise ActiveRecord::Rollback - works with save but when user calls
save! exception isnt thrown on failure (as it is expected to be).

c) calling connection.rollback_db_transaction
Seems to work but it is an ugly hack that has a side effect of
generating:
BEGIN, ..., ROLLBACK, COMMIT/ROLLBACK to the database that results in
warnings.

d) What is correct way of doing it?

e) Maybe I should use different mechanism rather than before_create
callback. Basically I need to attach a few other models to newly
created model. If saving of any model fails, I want to leave database
untouched and report failure to the user.

Regards.

> e) Maybe I should use different mechanism rather than before_create
> callback. Basically I need to attach a few other models to newly
> created model. If saving of any model fails, I want to leave database
> untouched and report failure to the user.

How can you do this in before_create when the new model that you're
attaching to doesn't exist yet? I would have though after_create makes
more sense?

(sorry that doesn't answer your question)

Xav

On 26.5.2008, at 2.28, Xavier Shay wrote:

>
>> e) Maybe I should use different mechanism rather than before_create
>> callback. Basically I need to attach a few other models to newly
>> created model. If saving of any model fails, I want to leave database
>> untouched and report failure to the user.
>
> How can you do this in before_create when the new model that you're
> attaching to doesn't exist yet? I would have though after_create makes
> more sense?

You can, to an extent. The associated objects get actually saved only
when the main object is saved. However, I didn't get this to work
correctly (at least in a fairly complex test setting) recently so I
switched to after_save and everything started to behave correctly. An
after_filter should work as well if everything is inside a transaction
and you use save! for saving the associated objects as well.

//jarkko

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--
Jarkko Laine
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http://dotherightthing.com
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