I've been using Paperclip to handle file uploads lately, and I wanted to be able to accept file "uploads" with a URL. We already knew how to accomplish this with attachment_fu, and getting it working in Paperclip wasn't too difficult.
This example shows a Photo model that has an Image attachment.
The technique we're using requires adding a *_remote_url (string) column for your attachment, which is used to store the original URL. So, in this case, we need to add a column named image_remote_url the photos table.
# db/migrate/20081210200032_add_image_remote_url_to_photos.rb class AddImageRemoteUrlToPhotos < ActiveRecord::Migration def self.up add_column :photos, :image_remote_url, :string end def self.down remove_column :photos, :image_remote_url end end
Nothing special is required for the controller...
# app/controllers/photos_controller.rb class PhotosController < ApplicationController def create @photo = Photo.new(params[:photo]) if @photo.save redirect_to photos_path else render :action => 'new' end end end
In the form, we a add a text_field called :image_url, so people can upload a file or provide a URL...
# app/views/photos/new.html.erb <%= error_messages_for :photo %> <% form_for :photo, :html => { :multipart => true } do |f| %> Upload a photo: <%= f.file_field :image %><br> ...or provide a URL: <%= f.text_field :image_url %><br> <%= f.submit 'Submit' %> <% end %>
The meaty stuff is in the Photo model. We need to require open-uri, add an attr_accessor :image_url, and do the normal has_attached_file stuff. Then, we add a before_validation callback to download the file in the image_url attribute (if provided) and save the original URL as image_remote_url. Finally, we do a validates_presence_of :image_remote_url, which allows us to rescue from the many exceptions that can be raised when attempting to download the file.
# app/models/photo.rb require 'open-uri' class Photo < ActiveRecord::Base attr_accessor :image_url has_attached_file :image # etc... before_validation :download_remote_image, :if => :image_url_provided? validates_presence_of :image_remote_url, :if => :image_url_provided?, :message => 'is invalid or inaccessible' private def image_url_provided? !self.image_url.blank? end def download_remote_image self.image = do_download_remote_image self.image_remote_url = image_url end def do_download_remote_image io = open(URI.parse(image_url)) def io.original_filename; base_uri.path.split('/').last; end io.original_filename.blank? ? nil : io rescue # catch url errors with validations instead of exceptions (Errno::ENOENT, OpenURI::HTTPError, etc...) end end
Everything will work as normal, including the creation of thumbnails, etc. Plus, since we're doing all of the hard stuff in the model, "uploading" a file via URL works from within script/console as well:
$ script/console Loading development environment (Rails 2.2.2) >> Photo.new(:image_url => 'http://www.google.com/intl/en_ALL/images/logo.gif') => #<Photo image_file_name: "logo.gif", image_remote_url: "http://www.google.com/intl/en_ALL/images/logo.gif">
Sweet.
Update: The example code has been updated to reflect thew suggestions left in the comments. The original_filename method is now defined on the fly. Thanks for the feedback! I've also split out a new method called do_download_remote_image, which can be used for stubbing out in tests with mocha:
Photo.any_instance.expects(:do_download_remote_image).returns(File.open("#{Rails.root}/testhttp://s3.amazonaws.com/almosteffortless/rails.png"))
Nuwan Chaturanga
Didier Lafforgue
Pierre
grarceSkypece
naresh
This looks incredibly useful. One issue, though, is that I don’t think you need the image_url_provided? method. Rails gives you that method via image_remote_url? (with the question mark). In fact, you should be able to use the :allow_blank option for the validates_presence_of call.
Great and useful post.