# File lib/rdf/redland/queryresults.rb, line 105
    def to_string(format_uri = nil, base_uri = nil)
      if self.is_graph?()
        tmpmodel=Model.new()
        tmpmodel.add_statements(self.as_stream())
        serializer=Serializer.new()
        return serializer.model_to_string(base_uri, tmpmodel)
      end

      if not self.is_boolean?() and not self.is_bindings?()
        raise RedlandError.new("Unknown query result format cannot be written as a string")
      end

      if format_uri
        format_uri = format_uri.uri
      end
      if base_uri
        base_uri = base_uri.uri
      end

      return Redland.librdf_query_results_to_string(@results, format_uri, base_uri)
    end