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