Rails - Oct 2006 - Understanding rails transactions execution.

Hi,

I''d like to understand how Rail''s handles rollbacks.  Say I
have the
following:

def action(...)

  User.transaction do
    user1 = User.new
    user1.attr1 = 5
    relationship = Relationship.new
    if user1.save
      ...do stuff...
    end

    if relationship.save
      ...do stuff...
    end
  end
end

My question is, say user1.save did not go through due to some UNIQUE 
constraint violoation in the db, does Rails continue execution to 
relationship.save?  Or does it throw an exception, and if so, what''s
the
exception that it throws to tell us that it did a ROLLBACK.  Since I''m 
doing a user1.save without the ''user1.save!'', instead of
throwing an
exception, it''ll return False.  So if that''s the case, does it
just
continue execution with relationship.save?

Thanks,

Sam

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On 10/1/06, Sam Donaldson
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
>
> Hi,
>
> I''d like to understand how Rail''s handles rollbacks.  Say
I have the
> following:
>
> def action(...)
>
>   User.transaction do
>     user1 = User.new
>     user1.attr1 = 5
>     relationship = Relationship.new
>     if user1.save
>       ...do stuff...
>     end
>
>     if relationship.save
>       ...do stuff...
>     end
>   end
> end
>
> My question is, say user1.save did not go through due to some UNIQUE
> constraint violoation in the db, does Rails continue execution to
> relationship.save?  Or does it throw an exception, and if so,
what''s the
> exception that it throws to tell us that it did a ROLLBACK.  Since
I''m
> doing a user1.save without the ''user1.save!'', instead of
throwing an
> exception, it''ll return False.  So if that''s the case,
does it just
> continue execution with relationship.save?

The database adapter would raise ActiveRecord::StatementInvalid. Your
transaction block would rescue the exception, rollback the db transaction,
and reraise the exception.

jeremy


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