If you sometimes need to attach many files to a rails model, we find on the web a lot of tutos with uploadify and so on. Here is a simple way to do it only with HTML5, paperclip and rails.

attachment.rb

class Attachment < ActiveRecord::Base
belongs_to :note
has_attached_file :attachment
end

note.rb

class Note < ActiveRecord::Base
has_many :attachments
def attachments_array=(array)
array.each do |file|
attachments.build(:attachment => file)
end
end
end

With only that little of HTML5 magic, we can upload has many files that we want only by adding this input file in the note form.

note_form.html

<input type=file name=attachments_array multiple />