Add _updated_at. To be used for cache busting.

No tests yet since I had problems getting the suite to run :/

README.rdoc

@@ -19,12 +19,14 @@ In your migrations:
       add_column :users, :avatar_file_name, :string
       add_column :users, :avatar_content_type, :string
       add_column :users, :avatar_file_size, :integer
+      add_column :users, :avatar_updated_at, :integer
     end
 
     def self.down
       remove_column :users, :avatar_file_name
       remove_column :users, :avatar_content_type
       remove_column :users, :avatar_file_size
+      remove_column :users, :avatar_updated_at
     end
   end
 

generators/paperclip/templates/paperclip_migration.rb

@@ -4,6 +4,7 @@ class <%= migration_name %> < ActiveRecord::Migration
     add_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_file_name, :string
     add_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_content_type, :string
     add_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_file_size, :integer
+    add_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_updated_at, :datetime
 <% end -%>
   end
 
@@ -12,6 +13,7 @@ class <%= migration_name %> < ActiveRecord::Migration
     remove_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_file_name
     remove_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_content_type
     remove_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_file_size
+    remove_column :<%= class_name.underscore.camelize.tableize %>, :<%= attachment %>_updated_at
 <% end -%>
   end
 end

lib/paperclip/attachment.rb

@@ -61,6 +61,7 @@ module Paperclip
       @instance[:"#{@name}_file_name"]    = uploaded_file.original_filename.strip.gsub /[^\w\d\.\-]+/, '_'
       @instance[:"#{@name}_content_type"] = uploaded_file.content_type.strip
       @instance[:"#{@name}_file_size"]    = uploaded_file.size.to_i
+      @instance[:"#{@name}_updated_at"]   = Time.now
 
       @dirty = true
 
@@ -230,6 +231,7 @@ module Paperclip
       @instance[:"#{@name}_file_name"]    = nil
       @instance[:"#{@name}_content_type"] = nil
       @instance[:"#{@name}_file_size"]    = nil
+      @instance[:"#{@name}_updated_at"]   = nil
     end
 
     def flush_errors #:nodoc:

test/helper.rb

@@ -32,6 +32,7 @@ def rebuild_model options = {}
     table.column :avatar_file_name, :string
     table.column :avatar_content_type, :string
     table.column :avatar_file_size, :integer
+    table.column :avatar_updated_at, :datetime
   end
 
   ActiveRecord::Base.send(:include, Paperclip)