pgx/data_row.go

package pgproto3

import (
	"bytes"
	"encoding/binary"
	"encoding/hex"
	"encoding/json"
)

type DataRow struct {
	Values [][]byte
}

func (*DataRow) Backend() {}

func (dst *DataRow) Decode(src []byte) error {
	if len(src) < 2 {
		return &invalidMessageFormatErr{messageType: "DataRow"}
	}
	rp := 0
	fieldCount := int(binary.BigEndian.Uint16(src[rp:]))
	rp += 2

	// If the capacity of the values slice is too small OR substantially too
	// large reallocate. This is too avoid one row with many columns from
	// permanently allocating memory.
	if cap(dst.Values) < fieldCount || cap(dst.Values)-fieldCount > 32 {
		dst.Values = make([][]byte, fieldCount, 32)
	} else {
		dst.Values = dst.Values[:fieldCount]
	}

	for i := 0; i < fieldCount; i++ {
		if len(src[rp:]) < 4 {
			return &invalidMessageFormatErr{messageType: "DataRow"}
		}

		msgSize := int(int32(binary.BigEndian.Uint32(src[rp:])))
		rp += 4

		// null
		if msgSize == -1 {
			dst.Values[i] = nil
		} else {
			if len(src[rp:]) < msgSize {
				return &invalidMessageFormatErr{messageType: "DataRow"}
			}

			dst.Values[i] = src[rp : rp+msgSize]
			rp += msgSize
		}
	}

	return nil
}

func (src *DataRow) MarshalBinary() ([]byte, error) {
	var bigEndian BigEndianBuf
	buf := &bytes.Buffer{}

	buf.WriteByte('D')
	buf.Write(bigEndian.Uint32(0))

	buf.Write(bigEndian.Uint16(uint16(len(src.Values))))

	for _, v := range src.Values {
		if v == nil {
			buf.Write(bigEndian.Int32(-1))
			continue
		}

		buf.Write(bigEndian.Int32(int32(len(v))))
		buf.Write(v)
	}

	binary.BigEndian.PutUint32(buf.Bytes()[1:5], uint32(buf.Len()-1))

	return buf.Bytes(), nil
}

func (src *DataRow) MarshalJSON() ([]byte, error) {
	formattedValues := make([]map[string]string, len(src.Values))
	for i, v := range src.Values {
		if v == nil {
			continue
		}

		var hasNonPrintable bool
		for _, b := range v {
			if b < 32 {
				hasNonPrintable = true
				break
			}
		}

		if hasNonPrintable {
			formattedValues[i] = map[string]string{"binary": hex.EncodeToString(v)}
		} else {
			formattedValues[i] = map[string]string{"text": string(v)}
		}
	}

	return json.Marshal(struct {
		Type   string
		Values []map[string]string
	}{
		Type:   "DataRow",
		Values: formattedValues,
	})
}