app/models/ckeditor/attachment_file.rb
class Ckeditor::AttachmentFile < Ckeditor::Asset
has_attached_file :data,
url: '/ckeditor_assets/attachments/:id/:filename',
path: ':rails_root/public/ckeditor_assets/attachments/:id/:filename'
validates_attachment_presence :data
validates_attachment_size :data, less_than: 100.megabytes
do_not_validate_attachment_file_type :data
def url_thumb
@url_thumb ||= Ckeditor::Utils.filethumb(filename)
end
end