sqltypes: add ToTime conversion funcs (#17178)

Signed-off-by: Derek Perkins <derek@nozzle.io>

go/sqltypes/value.go

@@ -26,6 +26,7 @@ import (
 	"math/big"
 	"strconv"
 	"strings"
+	"time"
 
 	"google.golang.org/protobuf/encoding/protowire"
 
@@ -435,6 +436,100 @@ func (v Value) String() string {
 	return fmt.Sprintf("%v(%s)", Type(v.typ), v.val)
 }
 
+// ToTime returns the value as a time.Time in UTC.
+// NULL values are returned as zero time.
+func (v Value) ToTime() (time.Time, error) {
+	return v.ToTimeInLocation(time.UTC)
+}
+
+// ToTimeInLocation returns the value as a time.Time in the provided location.
+// NULL values are returned as zero time.
+func (v Value) ToTimeInLocation(loc *time.Location) (time.Time, error) {
+	if v.Type() == Null {
+		return time.Time{}, nil
+	}
+	switch v.Type() {
+	case Datetime, Timestamp:
+		return datetimeToNative(v, loc)
+	case Date:
+		return dateToNative(v, loc)
+	default:
+		return time.Time{}, ErrIncompatibleTypeCast
+	}
+}
+
+// ErrInvalidTime is returned when we fail to parse a datetime
+// string from MySQL. This should never happen unless things are
+// seriously messed up.
+var ErrInvalidTime = errors.New("invalid MySQL time string")
+
+var isoTimeFormat = "2006-01-02 15:04:05.999999"
+var isoNullTime = "0000-00-00 00:00:00.000000"
+var isoTimeLength = len(isoTimeFormat)
+
+// parseISOTime pases a time string in MySQL's textual datetime format.
+// This is very similar to ISO8601, with some differences:
+//
+//   - There is no T separator between the date and time sections;
+//     a space is used instead.
+//   - There is never a timezone section in the string, as these datetimes
+//     are not timezone-aware. There isn't a Z value for UTC times for
+//     the same reason.
+//
+// Note that this function can handle both DATE (which should _always_ have
+// a length of 10) and DATETIME strings (which have a variable length, 18+
+// depending on the number of decimal sub-second places).
+//
+// Also note that this function handles the case where MySQL returns a NULL
+// time (with a string where all sections are zeroes) by returning a zeroed
+// out time.Time object. NULL time strings are not considered a parsing error.
+//
+// See: isoTimeFormat
+func parseISOTime(tstr string, loc *time.Location, minLen, maxLen int) (t time.Time, err error) {
+	tlen := len(tstr)
+	if tlen < minLen || tlen > maxLen {
+		err = ErrInvalidTime
+		return
+	}
+
+	if tstr == isoNullTime[:tlen] {
+		// This is what MySQL would send when the date is NULL,
+		// so return an empty time.Time instead.
+		// This is not a parsing error
+		return
+	}
+
+	if loc == nil {
+		loc = time.UTC
+	}
+
+	// Since the time format returned from MySQL never has a Timezone
+	// section, ParseInLocation will initialize the time.Time struct
+	// with the default `loc` we're passing here.
+	return time.ParseInLocation(isoTimeFormat[:tlen], tstr, loc)
+}
+
+// datetimeToNative converts a Datetime Value into a time.Time
+func datetimeToNative(v Value, loc *time.Location) (time.Time, error) {
+	// Valid format string offsets for a DATETIME
+	//  |DATETIME          |19+
+	//  |------------------|------|
+	// "2006-01-02 15:04:05.999999"
+	return parseISOTime(v.ToString(), loc, 19, isoTimeLength)
+}
+
+// dateToNative converts a Date Value into a time.Time.
+// Note that there's no specific type in the Go stdlib to represent
+// dates without time components, so the returned Time will have
+// their hours/mins/seconds zeroed out.
+func dateToNative(v Value, loc *time.Location) (time.Time, error) {
+	// Valid format string offsets for a DATE
+	//  |DATE     |10
+	//  |---------|
+	// "2006-01-02 00:00:00.000000"
+	return parseISOTime(v.ToString(), loc, 10, 10)
+}
+
 // EncodeSQL encodes the value into an SQL statement. Can be binary.
 func (v Value) EncodeSQL(b BinWriter) {
 	switch {

go/sqltypes/value_test.go

@@ -18,8 +18,10 @@ package sqltypes
 
 import (
 	"math"
+	"reflect"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 
@@ -611,6 +613,155 @@ func TestToUint32(t *testing.T) {
 	}
 }
 
+var randomLocation = time.FixedZone("Nowhere", 3*60*60)
+
+func DatetimeValue(str string) Value {
+	return TestValue(Datetime, str)
+}
+
+func DateValue(str string) Value {
+	return TestValue(Date, str)
+}
+
+func TestDatetimeToNative(t *testing.T) {
+	tcases := []struct {
+		val Value
+		loc *time.Location
+		out time.Time
+		err bool
+	}{{
+		val: DatetimeValue("1899-08-24 17:20:00"),
+		out: time.Date(1899, 8, 24, 17, 20, 0, 0, time.UTC),
+	}, {
+		val: DatetimeValue("1952-03-11 01:02:03"),
+		loc: time.Local,
+		out: time.Date(1952, 3, 11, 1, 2, 3, 0, time.Local),
+	}, {
+		val: DatetimeValue("1952-03-11 01:02:03"),
+		loc: randomLocation,
+		out: time.Date(1952, 3, 11, 1, 2, 3, 0, randomLocation),
+	}, {
+		val: DatetimeValue("1952-03-11 01:02:03"),
+		loc: time.UTC,
+		out: time.Date(1952, 3, 11, 1, 2, 3, 0, time.UTC),
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00.000000"),
+		out: time.Date(1899, 8, 24, 17, 20, 0, 0, time.UTC),
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00.000001"),
+		out: time.Date(1899, 8, 24, 17, 20, 0, int(1*time.Microsecond), time.UTC),
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00.123456"),
+		out: time.Date(1899, 8, 24, 17, 20, 0, int(123456*time.Microsecond), time.UTC),
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00.222"),
+		out: time.Date(1899, 8, 24, 17, 20, 0, int(222*time.Millisecond), time.UTC),
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00.1234567"),
+		err: true,
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00.1"),
+		out: time.Date(1899, 8, 24, 17, 20, 0, int(100*time.Millisecond), time.UTC),
+	}, {
+		val: DatetimeValue("0000-00-00 00:00:00"),
+		out: time.Time{},
+	}, {
+		val: DatetimeValue("0000-00-00 00:00:00.0"),
+		out: time.Time{},
+	}, {
+		val: DatetimeValue("0000-00-00 00:00:00.000"),
+		out: time.Time{},
+	}, {
+		val: DatetimeValue("0000-00-00 00:00:00.000000"),
+		out: time.Time{},
+	}, {
+		val: DatetimeValue("0000-00-00 00:00:00.0000000"),
+		err: true,
+	}, {
+		val: DatetimeValue("1899-08-24T17:20:00.000000"),
+		err: true,
+	}, {
+		val: DatetimeValue("1899-02-31 17:20:00.000000"),
+		err: true,
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00."),
+		out: time.Date(1899, 8, 24, 17, 20, 0, 0, time.UTC),
+	}, {
+		val: DatetimeValue("0000-00-00 00:00:00.000001"),
+		err: true,
+	}, {
+		val: DatetimeValue("1899-08-24 17:20:00 +02:00"),
+		err: true,
+	}, {
+		val: DatetimeValue("1899-08-24"),
+		err: true,
+	}, {
+		val: DatetimeValue("This is not a valid timestamp"),
+		err: true,
+	}}
+
+	for _, tcase := range tcases {
+		got, err := datetimeToNative(tcase.val, tcase.loc)
+		if tcase.err && err == nil {
+			t.Errorf("datetimeToNative(%v, %#v) succeeded; expected error", tcase.val, tcase.loc)
+		}
+		if !tcase.err && err != nil {
+			t.Errorf("datetimeToNative(%v, %#v) failed: %v", tcase.val, tcase.loc, err)
+		}
+		if !reflect.DeepEqual(got, tcase.out) {
+			t.Errorf("datetimeToNative(%v, %#v): %v, want %v", tcase.val, tcase.loc, got, tcase.out)
+		}
+	}
+}
+
+func TestDateToNative(t *testing.T) {
+	tcases := []struct {
+		val Value
+		loc *time.Location
+		out time.Time
+		err bool
+	}{{
+		val: DateValue("1899-08-24"),
+		out: time.Date(1899, 8, 24, 0, 0, 0, 0, time.UTC),
+	}, {
+		val: DateValue("1952-03-11"),
+		loc: time.Local,
+		out: time.Date(1952, 3, 11, 0, 0, 0, 0, time.Local),
+	}, {
+		val: DateValue("1952-03-11"),
+		loc: randomLocation,
+		out: time.Date(1952, 3, 11, 0, 0, 0, 0, randomLocation),
+	}, {
+		val: DateValue("0000-00-00"),
+		out: time.Time{},
+	}, {
+		val: DateValue("1899-02-31"),
+		err: true,
+	}, {
+		val: DateValue("1899-08-24 17:20:00"),
+		err: true,
+	}, {
+		val: DateValue("0000-00-00 00:00:00"),
+		err: true,
+	}, {
+		val: DateValue("This is not a valid timestamp"),
+		err: true,
+	}}
+
+	for _, tcase := range tcases {
+		got, err := dateToNative(tcase.val, tcase.loc)
+		if tcase.err && err == nil {
+			t.Errorf("dateToNative(%v, %#v) succeeded; expected error", tcase.val, tcase.loc)
+		}
+		if !tcase.err && err != nil {
+			t.Errorf("dateToNative(%v, %#v) failed: %v", tcase.val, tcase.loc, err)
+		}
+		if !reflect.DeepEqual(got, tcase.out) {
+			t.Errorf("dateToNative(%v, %#v): %v, want %v", tcase.val, tcase.loc, got, tcase.out)
+		}
+	}
+}
+
 func TestEncodeSQLStringBuilder(t *testing.T) {
 	testcases := []struct {
 		in     Value

go/vt/vitessdriver/convert.go

@@ -43,10 +43,8 @@ func (cv *converter) ToNative(v sqltypes.Value) (any, error) {
 		return v.ToUint64()
 	case v.IsFloat():
 		return v.ToFloat64()
-	case v.Type() == sqltypes.Datetime, v.Type() == sqltypes.Timestamp:
-		return datetimeToNative(v, cv.location)
-	case v.Type() == sqltypes.Date:
-		return dateToNative(v, cv.location)
+	case v.Type() == sqltypes.Datetime, v.Type() == sqltypes.Timestamp, v.Type() == sqltypes.Date:
+		return v.ToTimeInLocation(cv.location)
 	case v.IsQuoted() || v.Type() == sqltypes.Bit || v.Type() == sqltypes.Decimal:
 		out, err = v.ToBytes()
 	case v.Type() == sqltypes.Expression:

go/vt/vitessdriver/time.go

@@ -17,83 +17,12 @@ limitations under the License.
 package vitessdriver
 
 import (
-	"errors"
 	"time"
 
 	"vitess.io/vitess/go/sqltypes"
 )
 
-// ErrInvalidTime is returned when we fail to parse a datetime
-// string from MySQL. This should never happen unless things are
-// seriously messed up.
-var ErrInvalidTime = errors.New("invalid MySQL time string")
-
 var isoTimeFormat = "2006-01-02 15:04:05.999999"
-var isoNullTime = "0000-00-00 00:00:00.000000"
-var isoTimeLength = len(isoTimeFormat)
-
-// parseISOTime pases a time string in MySQL's textual datetime format.
-// This is very similar to ISO8601, with some differences:
-//
-//   - There is no T separator between the date and time sections;
-//     a space is used instead.
-//   - There is never a timezone section in the string, as these datetimes
-//     are not timezone-aware. There isn't a Z value for UTC times for
-//     the same reason.
-//
-// Note that this function can handle both DATE (which should _always_ have
-// a length of 10) and DATETIME strings (which have a variable length, 18+
-// depending on the number of decimal sub-second places).
-//
-// Also note that this function handles the case where MySQL returns a NULL
-// time (with a string where all sections are zeroes) by returning a zeroed
-// out time.Time object. NULL time strings are not considered a parsing error.
-//
-// See: isoTimeFormat
-func parseISOTime(tstr string, loc *time.Location, minLen, maxLen int) (t time.Time, err error) {
-	tlen := len(tstr)
-	if tlen < minLen || tlen > maxLen {
-		err = ErrInvalidTime
-		return
-	}
-
-	if tstr == isoNullTime[:tlen] {
-		// This is what MySQL would send when the date is NULL,
-		// so return an empty time.Time instead.
-		// This is not a parsing error
-		return
-	}
-
-	if loc == nil {
-		loc = time.UTC
-	}
-
-	// Since the time format returned from MySQL never has a Timezone
-	// section, ParseInLocation will initialize the time.Time struct
-	// with the default `loc` we're passing here.
-	return time.ParseInLocation(isoTimeFormat[:tlen], tstr, loc)
-}
-
-// datetimeToNative converts a Datetime Value into a time.Time
-func datetimeToNative(v sqltypes.Value, loc *time.Location) (time.Time, error) {
-	// Valid format string offsets for a DATETIME
-	//  |DATETIME          |19+
-	//  |------------------|------|
-	// "2006-01-02 15:04:05.999999"
-	return parseISOTime(v.ToString(), loc, 19, isoTimeLength)
-}
-
-// dateToNative converts a Date Value into a time.Time.
-// Note that there's no specific type in the Go stdlib to represent
-// dates without time components, so the returned Time will have
-// their hours/mins/seconds zeroed out.
-func dateToNative(v sqltypes.Value, loc *time.Location) (time.Time, error) {
-	// Valid format string offsets for a DATE
-	//  |DATE     |10
-	//  |---------|
-	// "2006-01-02 00:00:00.000000"
-	return parseISOTime(v.ToString(), loc, 10, 10)
-}
 
 // NewDatetime builds a Datetime Value
 func NewDatetime(t time.Time, defaultLoc *time.Location) sqltypes.Value {