Add timestamp to pgtype

2017-03-04 12:36:24 -06:00
parent ffb949054d
commit 3179e2debc
9 changed files with 782 additions and 30 deletions
@@ -0,0 +1,204 @@
+package pgtype
+
+import (
+	"fmt"
+	"io"
+	"reflect"
+	"time"
+
+	"github.com/jackc/pgx/pgio"
+)
+
+const pgTimestampFormat = "2006-01-02 15:04:05.999999999"
+
+// Timestamp represents the PostgreSQL timestamp type. The PostgreSQL
+// timestamp does not have a time zone. This presents a problem when
+// translating to and from time.Time which requires a time zone. It is highly
+// recommended to use timestamptz whenever possible. Timestamp methods either
+// convert to UTC or return an error on non-UTC times.
+type Timestamp struct {
+	Time   time.Time // Time must always be in UTC.
+	Status Status
+	InfinityModifier
+}
+
+// ConvertFrom converts src into a Timestamp and stores in dst. If src is a
+// time.Time in a non-UTC time zone, the time zone is discarded.
+func (dst *Timestamp) ConvertFrom(src interface{}) error {
+	switch value := src.(type) {
+	case Timestamp:
+		*dst = value
+	case time.Time:
+		*dst = Timestamp{Time: time.Date(value.Year(), value.Month(), value.Day(), value.Hour(), value.Minute(), value.Second(), value.Nanosecond(), time.UTC), Status: Present}
+	default:
+		if originalSrc, ok := underlyingTimeType(src); ok {
+			return dst.ConvertFrom(originalSrc)
+		}
+		return fmt.Errorf("cannot convert %v to Timestamp", value)
+	}
+
+	return nil
+}
+
+func (src *Timestamp) AssignTo(dst interface{}) error {
+	switch v := dst.(type) {
+	case *time.Time:
+		if src.Status != Present || src.InfinityModifier != None {
+			return fmt.Errorf("cannot assign %v to %T", src, dst)
+		}
+		*v = src.Time
+	default:
+		if v := reflect.ValueOf(dst); v.Kind() == reflect.Ptr {
+			el := v.Elem()
+			switch el.Kind() {
+			// if dst is a pointer to pointer, strip the pointer and try again
+			case reflect.Ptr:
+				if src.Status == Null {
+					el.Set(reflect.Zero(el.Type()))
+					return nil
+				}
+				if el.IsNil() {
+					// allocate destination
+					el.Set(reflect.New(el.Type().Elem()))
+				}
+				return src.AssignTo(el.Interface())
+			}
+		}
+		return fmt.Errorf("cannot assign %v into %T", src, dst)
+	}
+
+	return nil
+}
+
+// DecodeText decodes from src into dst. The decoded time is considered to
+// be in UTC.
+func (dst *Timestamp) DecodeText(r io.Reader) error {
+	size, err := pgio.ReadInt32(r)
+	if err != nil {
+		return err
+	}
+
+	if size == -1 {
+		*dst = Timestamp{Status: Null}
+		return nil
+	}
+
+	buf := make([]byte, int(size))
+	_, err = r.Read(buf)
+	if err != nil {
+		return err
+	}
+
+	sbuf := string(buf)
+	switch sbuf {
+	case "infinity":
+		*dst = Timestamp{Status: Present, InfinityModifier: Infinity}
+	case "-infinity":
+		*dst = Timestamp{Status: Present, InfinityModifier: -Infinity}
+	default:
+		tim, err := time.Parse(pgTimestampFormat, sbuf)
+		if err != nil {
+			return err
+		}
+
+		*dst = Timestamp{Time: tim, Status: Present}
+	}
+
+	return nil
+}
+
+// DecodeBinary decodes from src into dst. The decoded time is considered to
+// be in UTC.
+func (dst *Timestamp) DecodeBinary(r io.Reader) error {
+	size, err := pgio.ReadInt32(r)
+	if err != nil {
+		return err
+	}
+
+	if size == -1 {
+		*dst = Timestamp{Status: Null}
+		return nil
+	}
+
+	if size != 8 {
+		return fmt.Errorf("invalid length for timestamp: %v", size)
+	}
+
+	microsecSinceY2K, err := pgio.ReadInt64(r)
+	if err != nil {
+		return err
+	}
+
+	switch microsecSinceY2K {
+	case infinityMicrosecondOffset:
+		*dst = Timestamp{Status: Present, InfinityModifier: Infinity}
+	case negativeInfinityMicrosecondOffset:
+		*dst = Timestamp{Status: Present, InfinityModifier: -Infinity}
+	default:
+		microsecSinceUnixEpoch := microsecFromUnixEpochToY2K + microsecSinceY2K
+		tim := time.Unix(microsecSinceUnixEpoch/1000000, (microsecSinceUnixEpoch%1000000)*1000).UTC()
+		*dst = Timestamp{Time: tim, Status: Present}
+	}
+
+	return nil
+}
+
+// EncodeText writes the text encoding of src into w. If src.Time is not in
+// the UTC time zone it returns an error.
+func (src Timestamp) EncodeText(w io.Writer) error {
+	if done, err := encodeNotPresent(w, src.Status); done {
+		return err
+	}
+	if src.Time.Location() != time.UTC {
+		return fmt.Errorf("cannot encode non-UTC time into timestamp")
+	}
+
+	var s string
+
+	switch src.InfinityModifier {
+	case None:
+		s = src.Time.Format(pgTimestampFormat)
+	case Infinity:
+		s = "infinity"
+	case NegativeInfinity:
+		s = "-infinity"
+	}
+
+	_, err := pgio.WriteInt32(w, int32(len(s)))
+	if err != nil {
+		return nil
+	}
+
+	_, err = w.Write([]byte(s))
+	return err
+}
+
+// EncodeBinary writes the binary encoding of src into w. If src.Time is not in
+// the UTC time zone it returns an error.
+func (src Timestamp) EncodeBinary(w io.Writer) error {
+	if done, err := encodeNotPresent(w, src.Status); done {
+		return err
+	}
+	if src.Time.Location() != time.UTC {
+		return fmt.Errorf("cannot encode non-UTC time into timestamp")
+	}
+
+	_, err := pgio.WriteInt32(w, 8)
+	if err != nil {
+		return err
+	}
+
+	var microsecSinceY2K int64
+	switch src.InfinityModifier {
+	case None:
+		microsecSinceUnixEpoch := src.Time.Unix()*1000000 + int64(src.Time.Nanosecond())/1000
+		microsecSinceY2K = microsecSinceUnixEpoch - microsecFromUnixEpochToY2K
+	case Infinity:
+		microsecSinceY2K = infinityMicrosecondOffset
+	case NegativeInfinity:
+		microsecSinceY2K = negativeInfinityMicrosecondOffset
+	}
+
+	_, err = pgio.WriteInt64(w, microsecSinceY2K)
+	return err
+}