def family_ids(force_reload=false)
      return @family_ids unless @family_ids.nil? or force_reload
      
      transaction do
        reload_boundaries
        query = "SELECT id FROM #{self.class.quote_db_property(base_class.table_name)} " + 
                "WHERE #{nested_set_column(:left)} >= #{left} AND #{nested_set_column(:right)} <= #{right} " +
                "ORDER BY #{nested_set_column(:left)}"
        @family_ids = base_class.connection.select_values(query).map(&:to_i)
      end
    end
def family_ids(force_reload=false)
      return @family_ids unless @family_ids.nil? or force_reload
      
      transaction do
        reload_boundaries
        query = "SELECT id FROM #{self.class.quote_db_property(base_class.table_name)} " + 
                "WHERE #{nested_set_column(:left)} >= #{left} AND #{nested_set_column(:right)} <= #{right} " +
                "ORDER BY #{nested_set_column(:left)}"
        @family_ids = base_class.connection.select_values(query).map(&:to_i)
      end
    end
Returns the ids of the node and all nodes that descend from it.

 @return [Array[Integer]]