Rails - Jan 2011 - Paperclip custom Interpolation in url

Folks,

I have a simple model hierarchy (reduced to example as below)

class Post  < ActiveRecord::Base
     has_many :comments
end

class Comment  < ActiveRecord::Base
     belongs_to :post
  has_attached_file :photo,
      #  :url => "/assets/class_cal/<original post
date>/:id/:style/:basename.:extension"
  :url => "/assets/post/:post_date/:id/:style/:basename.:extension"
end

What I want to do: I am trying to insert the "original post date" in
the url with the :post_date (stored in the Post model) interpolation
function as defined in the Paperclip Interpolation module below.

--------------------------------------------
module Paperclip
    module Interpolations
        def post_date attachment, style_name
            attachment.<access the post class/model
here>.instance_read(:post_date).to_s
        end
    end
end
-------------------------------------------------

Problem: The problem I am running into is that I can''t seem to access
the post model object from the definition of post_date function above
- the attachment I understand refers to the Comment object. I have
tried attachment.post.instance_read(:post_date) but that doesn''t work.

Looking for thoughts/help on how to access a field in another model in
this situation?

Thanks for any pointers - I am on 2.3.8.

-S

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On Jan 8, 5:32 am, skt <stibre...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:
> --------------------------------------------
> module Paperclip
>     module Interpolations
>         def post_date attachment, style_name
>             attachment.<access the post class/model
> here>.instance_read(:post_date).to_s
>         end
>     end
> end
> -------------------------------------------------
>
> Problem: The problem I am running into is that I can''t seem to
access
> the post model object from the definition of post_date function above
> - the attachment I understand refers to the Comment object. I have
> tried attachment.post.instance_read(:post_date) but that doesn''t
work.
>
isn''t attachment.instance what gives you the associated AR object (ie
attachment.instance.post would be what you are looking for here) ?

Fred
> Looking for thoughts/help on how to access a field in another model in
> this situation?
>
> Thanks for any pointers - I am on 2.3.8.
>
> -S
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