# app/models/upload.rb
 
class Upload < ActiveRecord::Base
 
  # ...normal attachment_fu code (has_attachment, etc)...
 
  # allow uploads via URL
  require 'open-uri'
  attr_reader :url
  def url=(uri)
    return nil if uri.blank?
    io = (open(URI.parse(uri)) rescue return nil)
    (class << io; self; end;).class_eval do
      define_method(:original_filename) { base_uri.path.split('/').last }
    end
    self.uploaded_data = io
  end
end
 
# app/controllers/uploads_controller.rb
 
class UploadsController < ApplicationController
 
  # avoid raising exceptions for common errors (e.g. file not found)
  rescue_from Errno::ENOENT, :with => :url_upload_not_found
  rescue_from Errno::ETIMEDOUT, :with => :url_upload_not_found
  rescue_from OpenURI::HTTPError, :with => :url_upload_not_found
  rescue_from Timeout::Error, :with => :url_upload_not_found
 
  def new
    @upload = Upload.new
  end
 
  def create
    @upload = current_user.uploads.build(params[:upload])
    if @upload.save
      redirect_to files_path
    else
      render :action => "new"
    end
  end
 
  def url_upload_not_found
    flash[:notice] = "Sorry, the URL you provided was not valid."
    redirect_to new_upload_path
  end
end
 
# app/views/uploads/new.html.erb
 
<%= error_messages_for :upload %>
<% form_for @upload, :html => { :multipart => true } do |f| -%>
  <%= f.file_field :uploaded_data # normal upload, or... %>
  <%= f.text_field :url # upload via url %>
  <%= submit_tag "Upload", :disable_with => "Upload" %>
<% end %>