Paperclip :style depending on model (has_many polymorphic images)

Question

I have set up my models to use a polymorphic Image model. This is working fine, however I am wondering if it is possible to change the :styles setting for each model. Found some

Answer 1

class Banner < ActiveRecord::Base  

  belongs_to :banner_categoria
  validates :banner_categoria_id ,{:presence =>{:message => "não informada"}} 

  has_attached_file :arquivo
  after_initialize :init_attachment




  def init_attachment
    self.class.has_attached_file :arquivo,
      :url => "/system/:class/:attachment/:id/:style/:basename.:extension",
      :path => ":rails_root/public/system/:class/:attachment/:id/:style/:basename.:extension",
      :styles => hash = {
      :banner => {
        :geometry => "#{self.banner_categoria.largura}x#{self.banner_categoria.altura}>",
        :quality => 80
      },
      :thumb => "100x100#"
    }
  end

end

Answer 2

have the same problem in a production/staging server...BUT not in my local environment. I use same rails/paperclip versions in all servers (2.3.2 and 2.2.6)

Answer 3

After couple of hours of digging into source code of both, ActiveRecord and Paperclip, I think there's a solution involving a bit of monkey-patching hackery.

I haven't thoroughly tested it but seems to work for my humble needs.

Below is my config/initializers/activerecord_associations_patch.rb:

module ActiveRecord
  module Associations
    class HasManyAssociation

      def build_record(attributes)
        if options[:as] && owner
          # Unicorns
          reflection.build_association({}) do |record|
            set_owner_attributes(record)
            unless foreign_key_for?(record)
              record.public_send "#{options[:as]}=", owner
            end
            initialize_attributes(record)
            record.assign_attributes(attributes)
          end
        else
          # Classic Rails way
          reflection.build_association(attributes) do |record|
            initialize_attributes(record)
          end
        end
      end

    end
  end
end

Since reflection doesn't know our @owner, it first assigns the attributes which triggers call to record.#{instance}= (i.e. Image#file=), which in turn forwards it to #assign and performs post_processing hook, which in the end leads to calling styles Proc provided in has_attached_file without polymorphic imageable being set. huh…

I rewrote the method to build the record first and assign provided attributes later. Also, it accounts for record#new_record? in foreign_key_for? check.

In this way attributes are assigned once the record has been properly setup. At least i think so ;)

Cleaner solutions and constructive comments are most welcome :)

Answer 4

I've also met with the same problem and after searching for an elegant solution I didn't found anything "really" useful. So, here's my simple solution which seems alright for now; (tho I'm not sure if it has any downsides for the moment)

In model;

class Asset < ActiveRecord::Base
  belongs_to :assetable, polymorphic: true

  has_attached_file :attachment,  path: ":rails_root/#{path}/assets/images/:style/:filename",
                                  url: '/assets/images/:style/:filename',
                                  styles: -> (a) { a.instance.send(:styles) }
private
  def styles
    raise 'Undefined assetable.' unless assetable

    if assetable.class == Photo
      { small: 'x40', medium: '120x', large: '300x' }
    elsif assetable.class == Avatar
      { small: 'x40', medium: '120x', large: '300x' }
    else
      raise "Styles for #{assetable.class} is not defined."
    end
  end
end

In controller;

@photo = Photo.new
@photo.build_image(assetable: @photo, attachment: params[:photo][:image_attributes][:attachment])
@photo.save