v0.0.414 fix rfctime.Date bson marshalling for zero value

rfctime/date.go

@@ -102,6 +102,13 @@ func (t *Date) UnmarshalBSONValue(bt bsontype.Type, data []byte) error {
 		return err
 	}
 
+	if tt == "" {
+		t.Year = 0
+		t.Month = 0
+		t.Day = 0
+		return nil
+	}
+
 	v, err := time.Parse(t.FormatStr(), tt)
 	if err != nil {
 		return err
@@ -114,7 +121,10 @@ func (t *Date) UnmarshalBSONValue(bt bsontype.Type, data []byte) error {
 }
 
 func (t Date) MarshalBSONValue() (bsontype.Type, []byte, error) {
-	return bson.MarshalValue(t.TimeUTC().Format(t.FormatStr()))
+	if t.IsZero() {
+		return bson.MarshalValue("")
+	}
+	return bson.MarshalValue(t.String())
 }
 
 func (t Date) DecodeValue(dc bsoncodec.DecodeContext, vr bsonrw.ValueReader, val reflect.Value) error {
@@ -242,6 +252,10 @@ func (t *Date) ParseString(v string) error {
 	return nil
 }
 
+func (t Date) IsZero() bool {
+	return t.Year == 0 && t.Month == 0 && t.Day == 0
+}
+
 func NewDate(t time.Time) Date {
 	return Date{
 		Year:  t.Year(),