Rails extension for mysql insert or update

Mysql has a special 'INSERT ... ON DUPLICATE KEY UPDATE' statement which can be used for some models like e.g. ratings. Instead of something similar to this:
if m = Model.find(...) m.update else m = Model.new(params) m.save! end
You can just do this: m = Model.new(params) m.save!

when the row already exists in the database (detected by a unique-constraint violation) the values of that row are updated and saved, otherwise the new row is created.

My current solution is this:
module InsertOrUpdate def create create_or_update_impl end def update create_or_update_impl end def create_or_update_impl attrs = attributes_with_quotes(false,false) unless attrs.empty? self.id = connection.insert <<-end_sql ,"#{self.class.name} Create or update" INSERT INTO #{self.class.quoted_table_name} (#{quoted_column_names(attrs).join(', ')}) VALUES(#{attrs.values.join(', ')}) ON DUPLICATE KEY UPDATE #{update_values_partial}, id = LAST_INSERT_ID(id) end_sql end @new_record = false self.id end # returns "attr1 = 'value1', attr2 = 'value2', ..." def update_values_partial attrs = attributes_with_quotes(false,false) attrs.collect{|attr,value| "#{attr}=#{value}" }.join(",") end module ClassMethods def insert_or_update include InsertOrUpdate end end end ActiveRecord::Base.extend(InsertOrUpdate::ClassMethods)
You use it like this: class Model < ActiveRecord::Base insert_or_update # this includes the module and overwrites the default create and update methods end
Warning: You need mysql 5.1 so that LAST_INSERT_ID(id) works. (Mysql bug)