Rails - Sep 2008 - has_one :through with :source. How to alias association?

Hi to everyone,

I have the following models:

class Attachment < ActiveRecord::Base
  has_attachment  :content_type => [:image,
''application/pdf''],
                  :max_size => 3.megabytes,
                  :path_prefix => ''../private/attachments'',
                  :storage => :file_system,
                  :processor => :rmagick,
                  :thumbnails => { :small => ''32x32'',
:medium =>
''64x64'', :large => ''256x256'' }

  validates_as_attachment

  belongs_to  :attachable, :polymorphic => true
end

class Maker < ActiveRecord::Base
  validates_presence_of :name, :on => :create, :message =>
"can''t be
blank"
  validates_uniqueness_of :name, :message => ''name must be
unique''
  validates_presence_of :description, :on => :create, :message =>
"can''t
be blank"

  has_one :attachment, :as => :attachable, :dependent => :destroy
  has_one :logo, :through => :attachment, :source => :attachable,
:source_type => ''Maker'', :dependent => :destroy,
                      :conditions => [''attachments.content_type =
?'',
''image/jpeg'' ]

  has_many :products

  def deletable?
    self.products.empty?
  end

end

What I would like to accomplish is to have a "logo" association on the
"Maker" model which allows
me to fetch the logo (eventually) associated to the maker.

The row:

  has_one :logo, :through => :attachment, :source => :attachable,
:source_type => ''Maker'', :dependent => :destroy,
                      :conditions => [''attachments.content_type =
?'',
''image/jpeg'' ]


produces the same results of:

has_one :another_logo, :class_name => ''Attachment'',
:foreign_key =>
''attachable_id'', :conditions => [''attachable_type
= ?'', ''Maker'' ]

Which one is the best approach to achieve the desired result?

Thanks in advance for your help
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Sorry, of course I did wrote something worng.
> The row:
> 
>   has_one :logo, :through => :attachment, :source => :attachable,
> :source_type => ''Maker'', :dependent => :destroy,
>                       :conditions => [''attachments.content_type
= ?'',
> ''image/jpeg'' ]
> 
> 
> produces the same results of:
> 
> has_one :another_logo, :class_name => ''Attachment'',
:foreign_key =>
> ''attachable_id'', :conditions =>
[''attachable_type = ?'', ''Maker'' ]
The first row (has_one :logo) doesn''t produce the same result as the 
latter at all. It is a "circular"
reference, in the meaning that having:

m = Maker.find(:first)
m.logo returns itself, which is not what I wanted.

What I want is that "m.logo" returns the logo eventually associated
with
the object.
So far, the only way I''ve found is to use:

has_one :logo, :class_name => ''Attachment'', :foreign_key
=>
''attachable_id'', :conditions => [''attachable_type
= ?'', ''Maker'' ]

Now, the questions are:

- Is this the best way to accomplish this?
- Are there any other ways to get the same result?

Thanks again
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