Rails - Jun 2008 - 2.1 bug?: AR save doesn't work after gsub! on an attribute

All,

Rails 2.1
MySQL 5.x
Mac OS X 10.5

I think I''ve found a significant bug in ActiveRecord::save relating to
the use of gsub! on String attributes.

Given: A model m with one attribute x, a string.

If I attempt to update the value of x using m.x.gsub!, I can''t get the
modified value to save.  Here''s an example - notice how even though I
update the string value using gsub!, when I save the record, the change
doesn''t stick.  This definitely used to work before 2.1.
>> m = MyModel.create(:x => ''abc'')
=> #<MyModel id: 13, x: "abc", created_at: "2008-06-19
07:47:52",
updated_at: "2008-06-19 07:47:52">
>> m.x.gsub!(''abc'', ''123'')
=> "123"
>> m.x
=> "123"
>> m.save
=> true
>> m.id
=> 13
>> MyModel.find(13)
=> #<MyModel id: 13, x: "abc", created_at: "2008-06-19
07:47:52",
updated_at: "2008-06-19 07:47:52">

Notice, however, that if I use m.x = m.x.gsub, it will work:
>> m = MyModel.create(:x => ''abc'')
=> #<MyModel id: 14, x: "abc", created_at: "2008-06-19
07:52:50",
updated_at: "2008-06-19 07:52:50">
>> m.x = m.x.gsub(''abc'', ''123'')
=> "123"
>> m.x
=> "123"
>> m.save
=> true
>> m.id
=> 14
>> MyModel.find(14)
=> #<MyModel id: 14, x: "123", created_at: "2008-06-19
07:52:50",
updated_at: "2008-06-19 07:53:07">

Is this a bug in AR?  What''s changed about string attribute handling
that could explain this behavior?

Thanks,
Wes
-- 
Posted via http://www.ruby-forum.com/.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

On Jun 19, 8:54 am, Wes Gamble
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> All,
>
> Rails 2.1
> MySQL 5.x
> Mac OS X 10.5
>
> I think I''ve found a significant bug in ActiveRecord::save
relating to
> the use of gsub! on String attributes.
Have you got partial updates turned on? If you do that, then you can''t
edit attributes in place (ie using gsub!)

Fred

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

> Have you got partial updates turned on? If you do that, then you
can''t
> edit attributes in place (ie using gsub!)
> 
> Fred
Hmm... I don''t know.  Are they turned on by default?  How do I check?

Wes
-- 
Posted via http://www.ruby-forum.com/.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

On Jun 19, 9:06 am, Wes Gamble
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> > Have you got partial updates turned on? If you do that, then you
can''t
> > edit attributes in place (ie using gsub!)
>
> > Fred
>
> Hmm... I don''t know.  Are they turned on by default?  How do I
check?
>
Can''t remember the defaults. Check environment.rb or the initializers,
but if it''s on, ActiveRecord::Base.partial_updates will be true

Fred
> Wes
> --
> Posted viahttp://www.ruby-forum.com/.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

OK, fair enough.

0000isp37920l:Rails 2.1 Reference weyus$ script/console
Loading development environment (Rails 2.1.0)
>> ActiveRecord::Base.partial_updates
=> true

Can you explain why when partial_updates are enabled that updating a 
string attribute in place will not work, or point me to a relevant 
explanation?  I''m having trouble thinking that through - granted it is 
3:15 AM as well ;)...

Wes

-- 
Posted via http://www.ruby-forum.com/.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

On Jun 19, 9:19 am, Wes Gamble
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> OK, fair enough.
>
> 0000isp37920l:Rails 2.1 Reference weyus$ script/console
> Loading development environment (Rails 2.1.0)>>
ActiveRecord::Base.partial_updates
>
> => true
>
> Can you explain why when partial_updates are enabled that updating a
> string attribute in place will not work, or point me to a relevant
> explanation?  I''m having trouble thinking that through - granted
it is
> 3:15 AM as well ;)...
>
Because it doesn''t detect that that attribute has changed (since
it''s
the same object).
see also
http://groups.google.com/group/rubyonrails-core/browse_thread/thread/fc1a9575d316a52d/08f2b2fb8be6b5e6?lnk=gst&q=partial+updates#08f2b2fb8be6b5e6

"That''s going to be the way for Active Record attributes. If you
want
dirty tracking (and partial updates), you don''t get to do inplace
modifications."

Fred


> Wes
>
> --
> Posted viahttp://www.ruby-forum.com/.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

6:23pm here :)
(this is my vague understanding - haven''t played with this myself yet)

ActiveRecord tracks changes to fields based on calls to "model.field="
and (presumably) other things that change the value of the field
through a call to a method on the model object.

However, if you say:
   m.x.gsub!(''abc'', ''123'')
you are getting the value of m.x as a string, and then calling gsub!
which modifies the string in place.

ActiveRecord has no easy way to know you''ve done this - it would have
to somehow track all object changes to know that m.x is dirty and
needs saving.

If you said:
  m.x = m.x.gsub(''abc'',''123'')
everything would work fine, as the call to "=" marks the field as
changed.

- Korny

On Thu, Jun 19, 2008 at 6:19 PM, Wes Gamble
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
> OK, fair enough.
>
> 0000isp37920l:Rails 2.1 Reference weyus$ script/console
> Loading development environment (Rails 2.1.0)
>>> ActiveRecord::Base.partial_updates
> => true
>
> Can you explain why when partial_updates are enabled that updating a
> string attribute in place will not work, or point me to a relevant
> explanation?  I''m having trouble thinking that through - granted
it is
> 3:15 AM as well ;)...
>
> Wes
>
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>


-- 
Kornelis Sietsma korny at my surname dot com

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

From
>
http://groups.google.com/group/rubyonrails-core/browse_thread/thread/fc1a9575d316a52d/08f2b2fb8be6b5e6?lnk=gst&q=partial+updates#08f2b2fb8be6b5e6
> 

"Naturally, we can''t just change this as existing implementations
may
break. But I think we should make partial updates the default for apps
created with 2.1. And then finally the default for all by 3.0. We can
do this by making an option like config.active_record.partial_updates
= true that''s only set for apps created post-2.1 and when that option
is not set, we complain in the log about the deprecated status. "

FWIW, my app. was created on Rails 1.0, and this totally broke for me 
when I upgraded to 2.1, so I suspect that this sentiment didn''t get 
carried through.

Wes
-- 
Posted via http://www.ruby-forum.com/.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

On 19 Jun 2008, at 09:36, Wes Gamble wrote:
>
> From
>>
http://groups.google.com/group/rubyonrails-core/browse_thread/thread/fc1a9575d316a52d/08f2b2fb8be6b5e6?lnk=gst&q=partial+updates#08f2b2fb8be6b5e6
>>
>
>
> "Naturally, we can''t just change this as existing
implementations may
> break. But I think we should make partial updates the default for apps
> created with 2.1. And then finally the default for all by 3.0. We can
> do this by making an option like config.active_record.partial_updates
> = true that''s only set for apps created post-2.1 and when that
option
> is not set, we complain in the log about the deprecated status. "
>
> FWIW, my app. was created on Rails 1.0, and this totally broke for me
> when I upgraded to 2.1, so I suspect that this sentiment didn''t
get
> carried through.
THere was some flip-flopping over what the default should be - can''t  
remember what the final decision was.

Fred
>
>
> Wes
> -- 
> Posted via http://www.ruby-forum.com/.
>
> >

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Of course, you can just tell AR that you used gsub by calling
m.x_has_changed!
Or switch off partial updates in environment.rb.
-jm


On Jun 19, 11:01 am, Frederick Cheung
<frederick.che...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> On 19 Jun 2008, at 09:36, Wes Gamble wrote:
>
>
>
>
>
> > From
>
>>http://groups.google.com/group/rubyonrails-core/browse_thread/thread/...
>
> > "Naturally, we can''t just change this as existing
implementations may
> > break. But I think we should make partial updates the default for apps
> > created with 2.1. And then finally the default for all by 3.0. We can
> > do this by making an option like config.active_record.partial_updates
> > = true that''s only set for apps created post-2.1 and when
that option
> > is not set, we complain in the log about the deprecated status. "
>
> > FWIW, my app. was created on Rails 1.0, and this totally broke for me
> > when I upgraded to 2.1, so I suspect that this sentiment
didn''t get
> > carried through.
>
> THere was some flip-flopping over what the default should be -
can''t  
> remember what the final decision was.
>
> Fred
>
>
>
> > Wes
> > --
> > Posted viahttp://www.ruby-forum.com/.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Fjan,

Thanks for the tip.  That helps.

I have mixed feelings about this feature - since it requires me to write 
more verbose code in order to take advantage of it.  But I guess I can 
look at it as a performance optimization that I''m making a concession 
(code-wise) to get.

On the other hand, I see how managing the in-place updates is a bear (do 
you enumerate and override _all_ of the methods that modify stuff in 
place?  Is that even possible?).

I wonder why this happened on my upgraded app. even though it appears 
that it shouldn''t have?  Makes me wonder how an upgraded app. is 
distinguished from a new 2.1 app.?

Thanks,
Wes

-- 
Posted via http://www.ruby-forum.com/.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

On Thu, Jun 19, 2008 at 10:47 AM, Wes Gamble
<rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
>
> Fjan,
>
> Thanks for the tip.  That helps.
>
> I have mixed feelings about this feature - since it requires me to write
> more verbose code in order to take advantage of it.  But I guess I can
> look at it as a performance optimization that I''m making a
concession
> (code-wise) to get.
>
> On the other hand, I see how managing the in-place updates is a bear (do
> you enumerate and override _all_ of the methods that modify stuff in
> place?  Is that even possible?).
>
> I wonder why this happened on my upgraded app. even though it appears
> that it shouldn''t have?  Makes me wonder how an upgraded app. is
> distinguished from a new 2.1 app.?
All 2.1 apps have partial updates enabled.

I would prefer to freeze all attributes so you get an exception when
you try to modify them in-place. This is what the dirty plugin does.
Unfortunately there are too many quirks with certain frozen classes
(such as Date, which modifies itself) to make this change in 2.1.

Perhaps for 2.2.

jeremy

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

> Because it doesn''t detect that that attribute has changed (since
it''s
> the same object).
> see also
>
http://groups.google.com/group/rubyonrails-core/browse_thread/thread/fc1a9575d316a52d/08f2b2fb8be6b5e6?lnk=gst&q=partial+updates#08f2b2fb8be6b5e6
Note also that
instance.attribute = instance.attribute << ''a'' <<
''b'' also doesn''t
"qualify" as a changed attribute, since it reassigns it the same
object.
Go figure.
-R
-- 
Posted via http://www.ruby-forum.com/.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Fjan wrote:
> Of course, you can just tell AR that you used gsub by calling
> m.x_has_changed!
> Or switch off partial updates in environment.rb.
> -jm
> 
> 
I can''t find any reference to this type of method (_has_changed!) in
any
of my Rails gems.  It doesn''t appear to exist.

Wes
-- 
Posted via http://www.ruby-forum.com/.

--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---

Wes,

I think Fjan meant:

m.x_will_change!

Before modifying an attribute in-place:
  person.name_will_change!
  person.name << ''by''
  person.name_change    # => [''uncle bob'', ''uncle
bobby'']

http://api.rubyonrails.com/classes/ActiveRecord/Dirty.html

On Aug 27, 12:51 pm, Wes Gamble
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> Fjan wrote:
> > Of course, you can just tell AR that you used gsub by calling
> > m.x_has_changed!
> > Or switch off partial updates in environment.rb.
> > -jm
>
> I can''t find any reference to this type of method (_has_changed!)
in any
> of my Rails gems.  It doesn''t appear to exist.
>
> Wes
> --
> Posted viahttp://www.ruby-forum.com/.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
"Ruby on Rails: Talk" group.
To post to this group, send email to
rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
To unsubscribe from this group, send email to
rubyonrails-talk+unsubscribe@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/rubyonrails-talk?hl=en
-~----------~----~----~----~------~----~------~--~---