gistfile1.rb

      # Returns a copy of the attributes hash that only includes those
      # attributes that have values.
      def attributes_with_values
        returning Hash.new do |with_values|
          @attributes.each_pair do |name, value|
            if value⋅
              with_values[name] = value
            else
              column = column_for_attribute(name)
              if column.has_default? and !column.null then
                with_values[name] = value
              end
            end
          end
        end
      end

      # Creates a record with values matching those of the instance attributes
      # and returns its id.
      def create
        if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
          self.id = connection.next_sequence_value(self.class.sequence_name)
        end

        insertable_attributes = attributes_with_values
        quoted_attributes = attributes_with_quotes(true, true, insertable_attributes.keys )
        column_names = quoted_column_names( quoted_attributes )

        statement = if column_names.empty?
          connection.empty_insert_statement(self.class.table_name)
        else
          "INSERT INTO #{self.class.quoted_table_name} " +
          "(#{column_names.join(', ')}) " +
          "VALUES(#{quoted_attributes.values.join(', ')})"
        end

        self.id = connection.insert(statement, "#{self.class.name} Create",
          self.class.primary_key, self.id, self.class.sequence_name)

        @new_record = false
        id
      end