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Make A Remote URL Work Like A File Upload (in Rails)

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        Want to load a remote URL into an acts_as_attachment/attachment_fu model?  Use this little utility class.

  class UrlUpload
      "image/jpeg" => ["jpg", "jpeg", "jpe"],
      "image/gif" => ["gif"],
      "image/png" => ["png"]
    attr_reader :original_filename, :attachment_data
    def initialize(url)
      @attachment_data = open(url)
      @original_filename = determine_filename

    # Pass things like size, content_type, path on to the downloaded file
    def method_missing(symbol, *args)
      if self.attachment_data.respond_to? symbol
        self.attachment_data.send symbol, *args
      def determine_filename
        # Grab the path - even though it could be a script and not an actual file
        path = self.attachment_data.base_uri.path
        # Get the filename from the path, make it lowercase to handle those
        # crazy Win32 servers with all-caps extensions
        filename = File.basename(path).downcase
        # If the file extension doesn't match the content type, add it to the end, changing any existing .'s to _
        filename = [filename.gsub(/\./, "_"), EXTENSIONS[self.content_type].first].join(".") unless EXTENSIONS[self.content_type].any? {|ext| filename.ends_with?("." + ext) }
        # Return the result

Now when you have the URL you want to load, do something like this:

@model.uploaded_data =

Or better yet, make a pseudo-accessor on your aaa/attachment_fu model so you can stay "model-heavy".

def url=(value)
  self.uploaded_data =


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Snippets Manager replied on Fri, 2009/09/18 - 1:06pm

Do you need to include OpenURL? Model Trains

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Snippets Manager replied on Tue, 2009/06/02 - 11:06am

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Snippets Manager replied on Sun, 2007/12/16 - 4:43pm

@seanscribbs Where in open-uri.rb do I put that snippet?

Snippets Manager replied on Tue, 2007/11/20 - 5:21am

Yes you need to include the OpenURI library. Use this: require 'open-uri'

Snippets Manager replied on Mon, 2006/11/27 - 11:49pm

How do i use this script? It doesn´t seem to work. Do I need to include OpenURI or something?

Snippets Manager replied on Wed, 2006/03/29 - 10:25pm

One additional thing I had to do to make it fail-safe is open up the open-uri library and set it to always use Tempfile downloads, rather than StringIO. Here's a monkey-patch for it: # Make it always write to tempfiles, never StringIO OpenURI::Buffer.module_eval { remove_const :StringMax const_set :StringMax, 0 }