Dynamic use of :default_url in Paperclip

Question

I\'m trying to configure Paperclip to provide different missing images based on the instance\'s category attribute. Every category of the object has its own missing image.

Answer 1

You can pass a Proc as :default_url to paperclip. See https://github.com/thoughtbot/paperclip/blob/master/lib/paperclip/attachment.rb#L135. Paperclip will call that proc with the Attachment object as a parameter. The Attachment object has an accessor 'instance' that is the ActiveRecord object instance it's attached to. In your case you should have:

  has_attached_file :logo,
            :path => "/:id-:style-:filename",
            :url  => ":s3_eu_url",
            :default_url => lambda { |attach| "/logos/:style/#{attach.instance.category.name]}.png },
            :styles => { :large => "600x400>",
                         :medium => "300x200>",
                         :small => "100x75>",
                         :thumb => "60x42>" }