Add convenience functions to transform between edgedb.Duration and ti…

…me.Duration (#304)

export.go

@@ -288,6 +288,10 @@ var (
 	// The following options are recognized: host, port, user, database, password.
 	CreateClientDSN = edgedb.CreateClientDSN
 
+	// DurationFromNanoseconds creates a Duration represented as microseconds
+	// from a [time.Duration] represented as nanoseconds.
+	DurationFromNanoseconds = edgedbtypes.DurationFromNanoseconds
+
 	// NewDateDuration returns a new DateDuration
 	NewDateDuration = edgedbtypes.NewDateDuration
 

internal/edgedbtypes/datetime.go

@@ -660,6 +660,26 @@ func (d Duration) String() string {
 	return strings.Join(buf, "")
 }
 
+// AsNanoseconds returns [time.Duration] represented as nanoseconds,
+// after transforming from Duration microsecond representation.
+// Returns an error if the Duration is too long and would cause an overflow of
+// the internal int64 representation.
+func (d Duration) AsNanoseconds() (time.Duration, error) {
+	if int64(d) > math.MaxInt64/int64(time.Microsecond) ||
+		int64(d) < math.MinInt64/int64(time.Microsecond) {
+		return time.Duration(0), fmt.Errorf(
+			"Duration is too large to be represented as nanoseconds",
+		)
+	}
+	return time.Duration(d) * time.Microsecond, nil
+}
+
+// DurationFromNanoseconds creates a Duration represented as microseconds
+// from a [time.Duration] represented as nanoseconds.
+func DurationFromNanoseconds(d time.Duration) Duration {
+	return Duration(math.RoundToEven(float64(d) / 1e3))
+}
+
 // NewOptionalDuration is a convenience function for creating an
 // OptionalDuration with its value set to v.
 func NewOptionalDuration(v Duration) OptionalDuration {

internal/edgedbtypes/datetime_test.go

@@ -19,6 +19,7 @@ package edgedbtypes
 import (
 	"encoding/json"
 	"fmt"
+	"math"
 	"strings"
 	"testing"
 	"time"
@@ -758,6 +759,50 @@ func TestUnmarshalDuration(t *testing.T) {
 	}
 }
 
+func TestAsNanosecondsDuration(t *testing.T) {
+	var durationTruncMicroseconds = func(i int64) time.Duration {
+		return time.Duration(time.Duration(i).Microseconds() * 1000)
+	}
+
+	cases := []struct {
+		input    Duration
+		mustFail bool
+		expected time.Duration
+	}{
+		{Duration(math.MaxInt64), true, time.Duration(0)},
+		{Duration(math.MaxInt64 / 100), true, time.Duration(0)},
+		{Duration(math.MaxInt64/1000 + 1), true, time.Duration(0)},
+		// Maximum possible value:
+		{Duration(math.MaxInt64 / 1000), false,
+			durationTruncMicroseconds(math.MaxInt64)},
+		// Some arbitrary value within range
+		{Duration(math.MaxInt64 / 1452), false,
+			durationTruncMicroseconds(math.MaxInt64 / 1452 * 1000)},
+		{Duration(0), false, time.Duration(0)},
+		{Duration(math.MinInt64), true, time.Duration(0)},
+		{Duration(math.MinInt64 / 100), true, time.Duration(0)},
+		{Duration(math.MinInt64/1000 - 1), true, time.Duration(0)},
+		// Minimum possible value
+		{Duration(math.MinInt64 / 1000), false,
+			durationTruncMicroseconds(math.MinInt64)},
+		// Some arbitrary value within range
+		{Duration(math.MinInt64 / 6946), false,
+			durationTruncMicroseconds(math.MinInt64 / 6946 * 1000)},
+	}
+
+	for _, c := range cases {
+		t.Run(c.input.String(), func(t *testing.T) {
+			d, err := c.input.AsNanoseconds()
+			if c.mustFail {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+			assert.Equal(t, c.expected, d)
+		})
+	}
+}
+
 func TestMarshalOptionalDuration(t *testing.T) {
 	cases := []struct {
 		input    OptionalDuration

rstdocs/types.rst

@@ -75,6 +75,19 @@ as an int64 microsecond count.
     type Duration int64
 
 
+*function* DurationFromNanoseconds
+..................................
+
+.. code-block:: go
+
+    func DurationFromNanoseconds(d time.Duration) Duration
+
+DurationFromNanoseconds creates a Duration represented as microseconds
+from a `time.Duration <https://pkg.go.dev/time>`_ represented as nanoseconds.
+
+
+
+
 *function* ParseDuration
 ........................
 
@@ -87,6 +100,21 @@ ParseDuration parses an EdgeDB duration string.
 
 
 
+*method* AsNanoseconds
+......................
+
+.. code-block:: go
+
+    func (d Duration) AsNanoseconds() (time.Duration, error)
+
+AsNanoseconds returns `time.Duration <https://pkg.go.dev/time>`_ represented as nanoseconds,
+after transforming from Duration microsecond representation.
+Returns an error if the Duration is too long and would cause an overflow of
+the internal int64 representation.
+
+
+
+
 *method* String
 ...............