⚠️ DEPRECATED: paperclip_duplicate_check is no longer maintained. Paperclip itself has been deprecated upstream in favor of ActiveStorage; for duplicate detection on ActiveStorage attachments, use checksums directly. This is the final release.

Paperclip Duplicate Checker

Author	Tim Morgan
Version	1.0 (Apr 20, 2012)
License	Released under the MIT license.

This class extends Paperclip, adding a feature that forgoes uploading a replacement for an existing attachment file if the replacement is identical to the existing file.

In order for this to work, your model _must_have an <attachment>_fingerprint column, since MD5 fingerprints are used for comparison. To use, simply follow this example:

class MyModel < ActiveRecord::Base
  include CheckForDuplicateAttachedFile
  has_attachment :note
  check_for_duplicate_attached_file :note
end

Et voila! You save on bandwidth costs if your code re-uploads a lot of the same files.