From c61ff564729fbab84a9246d472a82cc298b7a4ef Mon Sep 17 00:00:00 2001
From: Mykhailo Temnokhud <mtemnohud@gmail.com>
Date: Wed, 14 Jan 2026 10:07:12 +0100
Subject: [PATCH] feat: add option to serialize DateTime values as UTC

---
 drift/lib/src/runtime/data_class.dart         | 25 +++++++++++++------
 .../drift3/lib/src/database/data_class.dart   | 18 ++++++++++---
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/drift/lib/src/runtime/data_class.dart b/drift/lib/src/runtime/data_class.dart
index 106ec3db1..e59703738 100644
--- a/drift/lib/src/runtime/data_class.dart
+++ b/drift/lib/src/runtime/data_class.dart
@@ -207,8 +207,10 @@ abstract class ValueSerializer {
   /// timestamp ([DateTime.millisecondsSinceEpoch]) or a string
   /// ([DateTime.toIso8601String]).
   /// In either case, date time values can be _deserialized_ from both formats.
-  const factory ValueSerializer.defaults(
-      {bool serializeDateTimeValuesAsString}) = _DefaultValueSerializer;
+  const factory ValueSerializer.defaults({
+    bool serializeDateTimeAsUtc,
+    bool serializeDateTimeValuesAsString,
+  }) = _DefaultValueSerializer;
 
   /// Converts the [value] to something that can be passed to
   /// [JsonCodec.encode].
@@ -220,9 +222,13 @@ abstract class ValueSerializer {
 }
 
 class _DefaultValueSerializer extends ValueSerializer {
+  final bool serializeDateTimeAsUtc;
   final bool serializeDateTimeValuesAsString;
 
-  const _DefaultValueSerializer({this.serializeDateTimeValuesAsString = false});
+  const _DefaultValueSerializer({
+    this.serializeDateTimeAsUtc = false,
+    this.serializeDateTimeValuesAsString = false,
+  });
 
   @override
   T fromJson<T>(dynamic json) {
@@ -234,7 +240,11 @@ class _DefaultValueSerializer extends ValueSerializer {
 
     if (typeList is List<DateTime?>) {
       if (json is int) {
-        return DateTime.fromMillisecondsSinceEpoch(json) as T;
+        return DateTime.fromMillisecondsSinceEpoch(
+              json,
+              isUtc: serializeDateTimeAsUtc,
+            )
+            as T;
       } else {
         return DateTime.parse(json.toString()) as T;
       }
@@ -246,7 +256,7 @@ class _DefaultValueSerializer extends ValueSerializer {
 
     // blobs are encoded as a regular json array, so we manually convert that to
     // a Uint8List
-    if (typeList is List<Uint8List?> && json is! Uint8List) {
+    if (json is! Uint8List) {
       final asList = (json as List).cast<int>();
       return Uint8List.fromList(asList) as T;
     }
@@ -257,9 +267,10 @@ class _DefaultValueSerializer extends ValueSerializer {
   @override
   dynamic toJson<T>(T value) {
     if (value is DateTime) {
+      final dateTime = (serializeDateTimeAsUtc ? value.toUtc() : value);
       return serializeDateTimeValuesAsString
-          ? value.toIso8601String()
-          : value.millisecondsSinceEpoch;
+          ? dateTime.toIso8601String()
+          : dateTime.millisecondsSinceEpoch;
     }
 
     return value;
diff --git a/future/drift3/lib/src/database/data_class.dart b/future/drift3/lib/src/database/data_class.dart
index 01498a319..cc7d48fb8 100644
--- a/future/drift3/lib/src/database/data_class.dart
+++ b/future/drift3/lib/src/database/data_class.dart
@@ -202,6 +202,7 @@ abstract class ValueSerializer {
   /// ([DateTime.toIso8601String]).
   /// In either case, date time values can be _deserialized_ from both formats.
   const factory ValueSerializer.defaults({
+    bool serializeDateTimeAsUtc,
     bool serializeDateTimeValuesAsString,
   }) = _DefaultValueSerializer;
 
@@ -215,9 +216,13 @@ abstract class ValueSerializer {
 }
 
 class _DefaultValueSerializer extends ValueSerializer {
+  final bool serializeDateTimeAsUtc;
   final bool serializeDateTimeValuesAsString;
 
-  const _DefaultValueSerializer({this.serializeDateTimeValuesAsString = false});
+  const _DefaultValueSerializer({
+    this.serializeDateTimeAsUtc = false,
+    this.serializeDateTimeValuesAsString = false,
+  });
 
   @override
   T fromJson<T>(dynamic json) {
@@ -229,7 +234,11 @@ class _DefaultValueSerializer extends ValueSerializer {
 
     if (typeList is List<DateTime?>) {
       if (json is int) {
-        return DateTime.fromMillisecondsSinceEpoch(json) as T;
+        return DateTime.fromMillisecondsSinceEpoch(
+              json,
+              isUtc: serializeDateTimeAsUtc,
+            )
+            as T;
       } else {
         return DateTime.parse(json.toString()) as T;
       }
@@ -252,9 +261,10 @@ class _DefaultValueSerializer extends ValueSerializer {
   @override
   dynamic toJson<T>(T value) {
     if (value is DateTime) {
+      final dateTime = (serializeDateTimeAsUtc ? value.toUtc() : value);
       return serializeDateTimeValuesAsString
-          ? value.toIso8601String()
-          : value.millisecondsSinceEpoch;
+          ? dateTime.toIso8601String()
+          : dateTime.millisecondsSinceEpoch;
     }
 
     return value;