Method NextResult

pgconn/pgconn.go:1618–1689

NextResult returns advances the MultiResultReader to the next result and returns true if a result is available.

()

// NextResult returns advances the MultiResultReader to the next result and returns true if a result is available.
func (mrr *MultiResultReader) NextResult() bool {
	for !mrr.closed && mrr.err == nil {
		msg, _ := mrr.pgConn.peekMessage()
		if _, ok := msg.(*pgproto3.DataRow); ok {
			if len(mrr.statementDescriptions) > 0 {
				rr := ResultReader{
					pgConn:            mrr.pgConn,
					multiResultReader: mrr,
					ctx:               mrr.ctx,
				}

				// This result corresponds to a prepared statement description that was provided when queuing the batch.
				sd := mrr.statementDescriptions[0]
				mrr.statementDescriptions = mrr.statementDescriptions[1:]

				resultFormats := mrr.resultFormats[0]
				mrr.resultFormats = mrr.resultFormats[1:]

				sdFields := sd.Fields
				rr.fieldDescriptions = rr.pgConn.getFieldDescriptionSlice(len(sdFields))

				err := combineFieldDescriptionsAndResultFormats(rr.fieldDescriptions, sdFields, resultFormats)
				if err != nil {
					rr.concludeCommand(CommandTag{}, err)
				}

				mrr.pgConn.resultReader = rr
				mrr.rr = &mrr.pgConn.resultReader
				return true
			}

			mrr.err = fmt.Errorf("unexpected DataRow message without preceding RowDescription")
			return false
		}

		msg, err := mrr.receiveMessage()
		if err != nil {
			return false
		}

		switch msg := msg.(type) {
		case *pgproto3.RowDescription:
			mrr.pgConn.resultReader = ResultReader{
				pgConn:            mrr.pgConn,
				multiResultReader: mrr,
				ctx:               mrr.ctx,
				fieldDescriptions: mrr.pgConn.getFieldDescriptionSlice(len(msg.Fields)),
			}
			convertRowDescription(mrr.pgConn.resultReader.fieldDescriptions, msg)

			mrr.rr = &mrr.pgConn.resultReader
			return true
		case *pgproto3.CommandComplete:
			mrr.pgConn.resultReader = ResultReader{
				commandTag:       mrr.pgConn.makeCommandTag(msg.CommandTag),
				commandConcluded: true,
				closed:           true,
			}