rails 3 polymorphic association with paperclip and multiple models

paperclip, polymorphic-associations, ruby-on-rails, ruby-on-rails-3

Solution

I do have a project in the works that is successfully using Paperclip and polymorphic associations. Let me show you what I have, and maybe you can apply it to your project:

class Song < ActiveRecord::Base
  ...
  has_one :artwork, :as => :artable, :dependent => :destroy
  accepts_nested_attributes_for :artwork
  ...
end

class Album < ActiveRecord::Base
  ...
  has_one :artwork, :as => :artable, :dependent => :destroy
  accepts_nested_attributes_for :artwork
  ...
end

class Artwork < ActiveRecord::Base
  belongs_to :artable, :polymorphic => true
  attr_accessible :artwork_content_type, :artwork_file_name, :artwork_file_size, :artwork

  # Paperclip
  has_attached_file :artwork,
    :styles => {
      :small => "100",
      :full => "400"
    }

  validates_attachment_content_type :artwork, :content_type => 'image/jpeg'
end

the songs form and the albums form include this as a partial:

<div class="field">
<%= f.fields_for :artwork do |artwork_fields| %>
  <%= artwork_fields.label :artwork %><br />
  <%= artwork_fields.file_field :artwork %>
<% end %>

don't forget to include :html => { :multipart => true } with the form

artworks_controller.rb

class ArtworksController < ApplicationController
  def create
    @artwork = Artwork.new(params[:artwork])

    if @artwork.save
        redirect_to @artwork.artable, notice: 'Artwork was successfully created.'
    else
        redirect_to @artwork.artable, notice: 'An error ocurred.'
    end
  end
end

and finally, an excerpt from songs_controller.rb:

def new
    @song = Song.new
    @song.build_artwork
end

Problem

I want to make polymorphic associations with paperclip, and allow my user to have one avatar and multiple images. Attachment model: ``` class Attachment < ActiveRecord::Base belongs_to :attachable, :polymorphic => true end class Avatar < Attachment has_attached_file :image, :styles => { :thumb => "150x150>", :view => "260x180>" }, end class Image < Attachment has_attached_file :image, :styles => { :thumb => "150x150>", :view => "260x180>" }, end ``` User Model: ``` has_one :avatar, :as => :attachable, :class_name => 'Attachment', :conditions => {:type => 'avatar'} accepts_nested_attributes_for :avatar ``` User Controller: ``` def edit @user.build_avatar end ``` User View form: ``` <%= form_for @user, :html => { :multipart => true } do |f| %> <%= f.fields_for :avatar do |asset| %> <% if asset.object.new_record? %> <%= asset.file_field :image %> <% end %> <% end %> ``` when I attempt to save the changes I get the error => unknown attribute: avatar if I remove the :class_name => 'attachment' in the has_one association I get the error => uninitialized constant User::Avatar I need to also attach avatars to blog posts, so I need the association to be polymorphic (or atleast i think so) I am stumped and any help would be greatly appreciated.

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