Rails core - Jan 2009 - [PATCH] Fix for obscure bug with eager-loading and nested includes

Hi all,

Here''s a patch for fixing a bug with nested includes and missing data
when
you use the old-style single query eager loading.

http://rails.lighthouseapp.com/projects/8994/tickets/1696

It''s a fairly obscure bug; we only saw it in a live 1.2.6 app after
it''d
been out for about a year and with 2.x''s multi-query eager loading for
most
cases it''s even less likely to occur, but it''s a bug
none-the-less.  What it
boils down to is: doing a find with 3 nested includes where the first
include has no data will cause a NoMethodError.  The problem is that
JoinDependency uses 2 arrays (associaitons and joins) to interrogate rows of
data and assumes they never get out of sync, which in this case, they do.
The fix is to find the correct join in the second array for the association
we are constructing, rather than just using the first join in the array.

I''d appreciate some more eyes on it as I''m not hugely
convinced that the
test case is complete / expressive enough.

Cheers,

Muz

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

On 5 Jan 2009, at 13:47, Murray Steele wrote:
> Hi all,
>
> Here''s a patch for fixing a bug with nested includes and missing  
> data when you use the old-style single query eager loading.
>
> http://rails.lighthouseapp.com/projects/8994/tickets/1696
>
> It''s a fairly obscure bug; we only saw it in a live 1.2.6 app
after
> it''d been out for about a year and with 2.x''s multi-query
eager
> loading for most cases it''s even less likely to occur, but
it''s a
> bug none-the-less.  What it boils down to is: doing a find with 3  
> nested includes where the first include has no data will cause a  
> NoMethodError.  The problem is that JoinDependency uses 2 arrays  
> (associaitons and joins) to interrogate rows of data and assumes  
> they never get out of sync, which in this case, they do.  The fix is  
> to find the correct join in the second array for the association we  
> are constructing, rather than just using the first join in the array.
>
> I''d appreciate some more eyes on it as I''m not hugely
convinced that
> the test case is complete / expressive enough.
>
Ah JoinDependency, my least favourite bit of rails :-) I''ll have a  
look at this one.

Fred
> Cheers,
>
> Muz
>
> >

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