module ActiveRecord module Locking module Optimistic private def _update_record(attribute_names = @attributes.keys) #:nodoc: return super unless locking_enabled? return 0 if attribute_names.empty? lock_col = self.class.locking_column previous_lock_value = send(lock_col).to_i increment_lock attribute_names += [lock_col] attribute_names.uniq! begin relation = self.class.unscoped if self.composite? stmt = relation.where( relation.cpk_id_predicate(relation.table, self.class.primary_key, id_was).and( relation.table[lock_col].eq(self.class.quote_value(previous_lock_value, column_for_attribute(lock_col))) ) ).arel.compile_update( arel_attributes_with_values_for_update(attribute_names), self.class.primary_key ) else stmt = relation.where( relation.table[self.class.primary_key].eq(id).and( relation.table[lock_col].eq(self.class.quote_value(previous_lock_value, column_for_attribute(lock_col))) ) ).arel.compile_update( arel_attributes_with_values_for_update(attribute_names), self.class.primary_key ) end affected_rows = self.class.connection.update stmt unless affected_rows == 1 raise ActiveRecord::StaleObjectError.new(self, "update") end affected_rows # If something went wrong, revert the version. rescue Exception send(lock_col + '=', previous_lock_value) raise end end end end end