Rails core - Feb 2008 - weird behavior of belongs_to referencing a model with set_table_name : a bug?

Hello all,

Since nobody answered the letter below in rubyonrails-talk, I''ve taken
the
courage to repost it here.
I looks like a bug, but I just refuse to believe it as it is such a basic
functionality of Active Record.

---------- Forwarded message ----------
From: Yuri Leikind <yuri.leikind@gmail.com>
Date: 5 feb. 2008 13:24
Subject: weird behavior of belongs_to referencing a model with
set_table_name
To: rubyonrails-talk@googlegroups.com

Hello all,

I am experiencing some really weird behavior of belongs_to with a model
where the table name is set by set_table_name


I have two simple models:


=== file legal_entity.rb


class LegalEntity < ActiveRecord::Base
  set_table_name ''legalentities''
end




=== file legal_entity_person.rb


class LegalEntityPerson < ActiveRecord::Base

  set_table_name ''legalentities_people''

  belongs_to :legal_entity, :foreign_key => ''
legalentity_id''
end


====

If I find a LegalEntityPerson object with :include => :legal_entity it works
as expected:


$  ./script/runner  ''a = LegalEntityPerson.find(:first, :include =>
:legal_entity); p a.legal_entity''
#<LegalEntity id: 1, name: "Some Company", legalentitytype_id:
3>


and looking a the log I see the select method with the 2 tables joined,
it''s
fine.


Now, if I drop :include => :legal_entity, a.legal_entity returns nil:


$  ./script/runner ''a = LegalEntityPerson.find(:first); p
a.legal_entity''
nil


And what is interesting is that there is no SQL query to the DB, that is,
there is  SELECT * FROM `legalentities_people` LIMIT 1 for the find
method, and nothing else, a.legal_entity silently returns nil without any
warnings or complaints.




If I rewrite my models like this following naming conventions:


=== file legalentity.rb


class Legalentity < ActiveRecord::Base


end




=== file legal_entity_person.rb


class LegalEntityPerson < ActiveRecord::Base

  set_table_name ''legalentities_people''

  belongs_to :legalentity
end


====

it works:


$  ./script/runner ''a = LegalEntityPerson.find(:first); p
a.legalentity''
#<Legalentity id: 1, name: "Some Company", legalentitytype_id:
3>




BUT!!!


If I specify :foreign_key explicitly like this:


  belongs_to :legalentity, :foreign_key => ''
legalentity_id''



it doesn''t work again:




Is there any reason behind this behavior or is it a bug?


I am using Rails 2.0.2,  mysql 5.0.51a, all running on OS X, and with the
following sql code you can reproduce it:


CREATE TABLE `legalentities` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `name` varchar(255) NOT NULL,
  `legalentitytype_id` int(10) unsigned NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;


INSERT INTO `legalentities` VALUES (1,''Some Company'',3);


CREATE TABLE `legalentities_people` (
  `id` int(10) unsigned NOT NULL auto_increment,
  `legalentity_id` int(10) unsigned NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;


INSERT INTO `legalentities_people` VALUES (1,1);

-- 
Best regards,
Yuri Leikind

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> Hello all,
>
>
> Since nobody answered the letter below in rubyonrails-talk, I''ve
taken the
> courage to repost it here.
> I looks like a bug, but I just refuse to believe it as it is such a basic
> functionality of Active Record.
It does seem strange.  Can you reproduce the bug in the active record
tests?  If so you can open a trac ticket and we can take a look at it.


-- 
Cheers

Koz

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Hi, I think I have a related problem (that I was about to post)

...

I have the following problem With a legacy Database:

class User < ActiveRecord::Base
  set_table_name :jos_users

  has_many :orders
  has_many :order_items, :through => :orders
end

class Order < ActiveRecord::Base
  set_table_name :jos_vm_orders
  set_primary_key :order_id

  has_many :order_items
  belongs_to :user
end

class OrderItem < ActiveRecord::Base
  set_table_name :jos_vm_order_item
  set_primary_key :order_item_id

  belongs_to :order
end


When I try to get all order items for a specific user I get an
error:
>> u=User.find(63).order_items
ActiveRecord::StatementInvalid: Mysql::Error: Unknown column 
''jos_vm_orders.order_item_id'' in ''on
clause'': SELECT jos_vm_order_item.*
FROM jos_vm_order_item  INNER JOIN jos_vm_orders ON 
jos_vm_order_item.order_id = jos_vm_orders.order_item_id    WHERE 
((jos_vm_orders.user_id = 63))
  from 
/var/lib/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract_adapter.rb:150:in
`log''

I don''t understand why rails is trying to get 
jos_vm_orders.order_item_id instead of jos_vm_orders.order_id, since the 
primary key of orders table os order_id.

Can somebody help.

Tahnks,
Cláudio Caseiro
-- 
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On 2/11/08, Cláudio Caseiro <ruby-forum-incoming@andreas-s.net>
wrote:
>
> Hi, I think I have a related problem (that I was about to post)
>
> ...
>
> I have the following problem With a legacy Database:
>
> class User < ActiveRecord::Base
>   set_table_name :jos_users
>
>   has_many :orders
You need to add the option :foreign_key => "order_id"

so
   has_many :orders, :foreign_key => "order_id"
>   has_many :order_items, :through => :orders
> end
>
> class Order < ActiveRecord::Base
>   set_table_name :jos_vm_orders
>   set_primary_key :order_id
>
>   has_many :order_items
>   belongs_to :user
> end
>
> class OrderItem < ActiveRecord::Base
>   set_table_name :jos_vm_order_item
>   set_primary_key :order_item_id
>
>   belongs_to :order
> end
>
>
> When I try to get all order items for a specific user I get an error:
> >> u=User.find(63).order_items
> ActiveRecord::StatementInvalid: Mysql::Error: Unknown column
> ''jos_vm_orders.order_item_id'' in ''on
clause'': SELECT jos_vm_order_item.*
> FROM jos_vm_order_item  INNER JOIN jos_vm_orders ON
> jos_vm_order_item.order_id = jos_vm_orders.order_item_id    WHERE
> ((jos_vm_orders.user_id = 63))
>   from
>
/var/lib/gems/1.8/gems/activerecord-2.0.2/lib/active_record/connection_adapters/abstract_adapter.rb:150:in
> `log''
>
> I don''t understand why rails is trying to get
> jos_vm_orders.order_item_id instead of jos_vm_orders.order_id, since the
> primary key of orders table os order_id.
>
> Can somebody help.
>
> Tahnks,
> Cláudio Caseiro
> --
> Posted via http://www.ruby-forum.com/.
>
> >
>

-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/

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With that foreign_key I still have the problem, but I don''t think I
need
any foreign_key.
I''m in class User, so if I need any foreign_key in a has_many 
association it would be :user_id, but since that is the default I don''t
need any.

I think the problem is that the join is using the primary_key defined in 
the OrderItem class for the order table, what is not correct. I changed 
that to "set_primary_key :foo" and  I get

ActiveRecord::StatementInvalid: Mysql::Error: Unknown column 
''jos_vm_orders.foo'' in ''on clause'': SELECT
`jos_vm_order_item`.* FROM
`jos_vm_order_item`  INNER JOIN jos_vm_orders ON 
jos_vm_order_item.order_id = jos_vm_orders.foo    WHERE 
((`jos_vm_orders`.user_id = 63))

Any help?
Thanks,
Claudio Caseiro

Rick Denatale wrote:
> On 2/11/08, Cl�udio Caseiro <ruby-forum-incoming@andreas-s.net>
wrote:
>>   has_many :orders
> You need to add the option :foreign_key => "order_id"
> 
> so
>    has_many :orders, :foreign_key => "order_id"
> 
>>
>> ActiveRecord::StatementInvalid: Mysql::Error: Unknown column
>> primary key of orders table os order_id.
>>
>> Can somebody help.
>>
>> Tahnks,
>> Cl�udio Caseiro
>> --
>> Posted via http://www.ruby-forum.com/.
>>
>> >
>>
> 
> 
> --
> Rick DeNatale
> 
> My blog on Ruby
> http://talklikeaduck.denhaven2.com/
-- 
Posted via http://www.ruby-forum.com/.

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On 12.2.2008, at 12.10, Cláudio Caseiro wrote:
>
> With that foreign_key I still have the problem, but I don''t think
I
> need
> any foreign_key.
> I''m in class User, so if I need any foreign_key in a has_many
> association it would be :user_id, but since that is the default I  
> don''t
> need any.
>
> I think the problem is that the join is using the primary_key  
> defined in
> the OrderItem class for the order table, what is not correct. I  
> changed
> that to "set_primary_key :foo" and  I get
>
> ActiveRecord::StatementInvalid: Mysql::Error: Unknown column
> ''jos_vm_orders.foo'' in ''on clause'':
SELECT `jos_vm_order_item`.* FROM
> `jos_vm_order_item`  INNER JOIN jos_vm_orders ON
> jos_vm_order_item.order_id = jos_vm_orders.foo    WHERE
> ((`jos_vm_orders`.user_id = 63))
>
> Any help?
Can you test whether you have the same problems if you change your  
database to use the standard Rails naming scheme, i.e. so that you  
don''t have to use any of the table_name, set_primary_key etc. methods?
I''m not suggesting that you''d have to do it in your actual
product,
but it could help figuring out whether some of them is breaking the  
scheme.

//jarkko

--
Jarkko Laine
http://jlaine.net
http://dotherightthing.com
http://www.railsecommerce.com
http://odesign.fi