Rails - Jan 2009 - self-referential joins with :through raises TypeError

I have a simple referral system composed of Users and Referrals.

The users table has an id value, of course.  The referrals table has
referer_id and referee_id.  The relationships are set up as follows:

class User < ActiveRecord::Base
  has_many  :referrals,
            :foreign_key => "referer_id"

  has_one :referer,
          :through => :referrals,
          :source => :referer

  has_many  :referees,
            :through => :referrals,
            :source => :referee

class Referral < ActiveRecord::Base
  belongs_to  :referer,
              :class_name => :user,
              :foreign_key => "referer_id"

  belongs_to :referee,
          :class_name => :user,
          :foreign_key => "referee_id"

Most of this works.  User.referrals returns all the referral objects.
Referral.referer and Referral.referee both return the appropriate
objects.  But the User.referer/referee methods both raise the same
error:
>> user.referer
TypeError: can''t convert Symbol into String

I would like User.referer to return the single user object that is their
referer.  And User.referees would return an array of user objects that
were refered.  What am I doing wrong here?
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On 2 Jan 2009, at 17:36, Taylor Strait wrote:
>
> class Referral < ActiveRecord::Base
>  belongs_to  :referer,
>              :class_name => :user,
>              :foreign_key => "referer_id"
>
>  belongs_to :referee,
>          :class_name => :user,
>          :foreign_key => "referee_id"
>
> Most of this works.  User.referrals returns all the referral objects.
> Referral.referer and Referral.referee both return the appropriate
> objects.  But the User.referer/referee methods both raise the same
> error:
>
The class_name option should really be a string (ie :class_name =>  
''User'')

Fred
>>> user.referer
> TypeError: can''t convert Symbol into String
>
> I would like User.referer to return the single user object that is  
> their
> referer.  And User.referees would return an array of user objects that
> were refered.  What am I doing wrong here?
> -- 
> Posted via http://www.ruby-forum.com/.
>
> >

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Frederick Cheung wrote:
> On 2 Jan 2009, at 17:36, Taylor Strait wrote:
>> Most of this works.  User.referrals returns all the referral objects.
>> Referral.referer and Referral.referee both return the appropriate
>> objects.  But the User.referer/referee methods both raise the same
>> error:
>>
> 
> The class_name option should really be a string (ie :class_name =>
> ''User'')
> 
> Fred
Thanks that solved the issue.

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Taylor Strait wrote:
> Frederick Cheung wrote:
>> On 2 Jan 2009, at 17:36, Taylor Strait wrote:
>>> Most of this works.  User.referrals returns all the referral
objects.
>>> Referral.referer and Referral.referee both return the appropriate
>>> objects.  But the User.referer/referee methods both raise the same
>>> error:
>>>
>> 
>> The class_name option should really be a string (ie :class_name =>
>> ''User'')
>>
Actually I spoke too soon.  User.referer always returns nil, even if 
there is a referral record with appropriate referee_id and referer_id. 
Also, if I do user1.referer = user2 a NoMethodError is raised:

NoMethodError: undefined method `update_attributes'' for 
#<Class:0x237de24>

User.referees does correctly return an array of user objects, though.

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The SQL generated by user1.referer is

SELECT "users".* FROM "users" INNER JOIN referrals ON
users.id =
referrals.referer_id WHERE (("referrals".referer_id = 1))

But it should be using WHERE referrals.referee_id = 1 instead of 
referer_id = 1.  I''ve tinkered with various permutations but cannot
make
it query for users.id = referer_id WHERE referee_id = x.  Any thoughts?
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Never fixed it :(
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http://frozenplague.net/2008/04/self-referrential-relationships/
-----
Ryan Bigg
Freelancer
http://frozenplague.net







On 06/01/2009, at 5:51 AM, Taylor Strait wrote:
>
> Never fixed it :(
> --  
> Posted via http://www.ruby-forum.com/.
>
> >

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On Jan 5, 7:21 pm, Taylor Strait
<rails-mailing-l...-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org>
wrote:
> Never fixed it :(
If referrals are all the referrals made by that user (since it uses
the referer_id foreign key) it seems to me that will never get you a
user''s referer (unless the use referred themselves).

You''d want to go through the referrals table using the other key.

Fred
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