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attachment_fu Now With Local File Fu

Posted by Ben Reubenstein Fri, 04 Jan 2008 17:50:00 GMT

In the beginning there was file_column. It was an excellent plugin for handling file uploads and image processing with the added bonus of being able to simply pass a file to it and have it work without a file upload via a form. One thing that file_column didn't do was fill in your db with file attribute goodness that could be used to create logic around a particular file. attachment_fu handled this along with the ability to use multiple image processors. For detailed info on attachment_fu, check out Mike Clark's article.

In order to add some local_file_fu to attachment_fu so you can pass a local file directly to it, you have to take your local file and turn it into a temporary file that you can pass to attachment_fu's uploaded_data method. I altered the solution outlined here for my solution.

1. Create a class in your models directory in a file called local_file.rb.

require 'tempfile'
class LocalFile
 # The filename, *not* including the path, of the "uploaded" file
 attr_reader :original_filename
 # The content type of the "uploaded" file
 attr_reader :content_type

 def initialize(path)
  raise "#{path} file does not exist" unless File.exist?(path)
  content_type ||= @@image_mime_types[File.extname(path)]
  raise "Unrecognized MIME type for #{path}" unless content_type
  @content_type = content_type
  @original_filename = File.basename(path)
  @tempfile = Tempfile.new(@original_filename)
  FileUtils.copy_file(path, @tempfile.path)
 end

 def path #:nodoc:
  @tempfile.path
 end
 alias local_path path

 def method_missing(method_name, *args, &block) #:nodoc:
  @tempfile.send(method_name, *args, &block)
 end
end


2. In order for attachment_fu to pass validations, you need to set the mime type of the file. This would usually come from the form when it is uploaded, but since we are using a local file, we'll set our mime types in environment.rb. At the end of the file add the various mime types you will need:

@@image_mime_types ||= { ".gif" => "image/gif", ".ief" => "image/ief", ".jpe" => "image/jpeg", ".jpeg" => "image/jpeg", ".jpg" => "image/jpeg", ".pbm" => "image/x-portable-bitmap", ".pgm" => "image/x-portable-graymap", ".png" => "image/png", ".pnm" => "image/x-portable-anymap", ".ppm" => "image/x-portable-pixmap", ".ras" => "image/cmu-raster", ".rgb" => "image/x-rgb", ".tif" => "image/tiff", ".tiff" => "image/tiff", ".xbm" => "image/x-xbitmap", ".xpm" => "image/x-xpixmap", ".xwd" => "image/x-xwindowdump" }.freeze

3. Now in your code that creates the model that has_attachments you can simply do the following:

model = Model.new()
model.uploaded_data = LocalFile.new(FULL_PATH_TO_FILE)
model.save


As always, comment on anything you have issues with or suggestions.