has_one :through with :source. How to alias association?

rubyonrails-talk
1

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

2

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