Saturday, May 12, 2007

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
# Add valid extensions here if you want stuff other than images --
# this helps the webserver set the right content type
"image/jpeg" => ["jpg", "jpeg", "jpe"],
"image/gif" => ["gif"],
"image/png" => ["png"]
attr_reader :original_filename, :content_type, :attachment_data
def initialize(url)
@attachment_data = open(url)
@content_type = self.attachment_data.content_type
@original_filename = determine_filename

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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