Fix date conversion on the server-side

src/Umbraco.Core/Extensions/ObjectExtensions.cs

@@ -1,4 +1,4 @@
 // Copyright (c) Umbraco.
 // See LICENSE for more details.
 
 using System.Collections;
@@ -219,6 +219,24 @@
                 }
             }
 
+            if (target == typeof(DateTime) && input is DateTimeOffset dateTimeOffset)
+            {
+                // IMPORTANT: for compatability with various editors, we must discard any Offset information and assume UTC time here
+                return Attempt.Succeed((object?)new DateTime(
+                    new DateOnly(dateTimeOffset.Year, dateTimeOffset.Month, dateTimeOffset.Day),
+                    new TimeOnly(dateTimeOffset.Hour, dateTimeOffset.Minute, dateTimeOffset.Second, dateTimeOffset.Millisecond, dateTimeOffset.Microsecond),
+                    DateTimeKind.Utc));
+            }
+
+            if (target == typeof(DateTimeOffset) && input is DateTime dateTime)
+            {
+                // IMPORTANT: for compatability with various editors, we must discard any DateTimeKind information and assume UTC time here
+                return Attempt.Succeed((object?)new DateTimeOffset(
+                    new DateOnly(dateTime.Year, dateTime.Month, dateTime.Day),
+                    new TimeOnly(dateTime.Hour, dateTime.Minute, dateTime.Second, dateTime.Millisecond, dateTime.Microsecond),
+                    TimeSpan.Zero));
+            }
+
             TypeConverter? inputConverter = GetCachedSourceTypeConverter(inputType, target);
             if (inputConverter != null)
             {

src/Umbraco.Core/PropertyEditors/ValueConverters/DatePickerValueConverter.cs

@@ -20,23 +20,19 @@ public override object ConvertSourceToIntermediate(IPublishedElement owner, IPub
 
     internal static DateTime ParseDateTimeValue(object? source)
     {
-        if (source == null)
+        if (source is null)
         {
             return DateTime.MinValue;
         }
 
-        // in XML a DateTime is: string - format "yyyy-MM-ddTHH:mm:ss"
-        // Actually, not always sometimes it is formatted in UTC style with 'Z' suffixed on the end but that is due to this bug:
-        // http://issues.umbraco.org/issue/U4-4145, http://issues.umbraco.org/issue/U4-3894
-        // We should just be using TryConvertTo instead.
-        if (source is string sourceString)
+        if (source is DateTime dateTimeValue)
         {
-            Attempt<DateTime> attempt = sourceString.TryConvertTo<DateTime>();
-            return attempt.Success == false ? DateTime.MinValue : attempt.Result;
+            return dateTimeValue;
         }
 
-        // in the database a DateTime is: DateTime
-        // default value is: DateTime.MinValue
-        return source is DateTime dateTimeValue ? dateTimeValue : DateTime.MinValue;
+        Attempt<DateTime> attempt = source.TryConvertTo<DateTime>();
+        return attempt.Success
+            ? attempt.Result
+            : DateTime.MinValue;
     }
 }

tests/Umbraco.Tests.UnitTests/Umbraco.Core/CoreThings/ObjectExtensionsTests.cs

@@ -1,4 +1,4 @@
 // Copyright (c) Umbraco.
 // See LICENSE for more details.
 
 using System;
@@ -11,6 +11,7 @@
 using Umbraco.Cms.Core.PropertyEditors;
 using Umbraco.Cms.Tests.Common.TestHelpers;
 using Umbraco.Extensions;
+using DateTimeOffset = System.DateTimeOffset;
 
 namespace Umbraco.Cms.Tests.UnitTests.Umbraco.Core.CoreThings;
 
@@ -332,6 +333,50 @@
         Assert.AreEqual("This is a string", conv.Result);
     }
 
+    [Test]
+    public void CanConvertDateTimeOffsetToDateTime()
+    {
+        var dateTimeOffset = new DateTimeOffset(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03), TimeSpan.Zero);
+        var result = dateTimeOffset.TryConvertTo<DateTime>();
+        Assert.IsTrue(result.Success);
+        Assert.Multiple(() =>
+        {
+            Assert.AreEqual(new DateTime(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03)), result.Result);
+            Assert.AreEqual(DateTimeKind.Utc, result.Result.Kind);
+        });
+    }
+
+    [Test]
+    public void CanConvertDateTimeToDateTimeOffset()
+    {
+        var dateTime = new DateTime(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03), DateTimeKind.Utc);
+        var result = dateTime.TryConvertTo<DateTimeOffset>();
+        Assert.IsTrue(result.Success);
+        Assert.AreEqual(new DateTimeOffset(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03), TimeSpan.Zero), result.Result);
+    }
+
+    [Test]
+    public void DiscardsOffsetWhenConvertingDateTimeOffsetToDateTime()
+    {
+        var dateTimeOffset = new DateTimeOffset(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03), TimeSpan.FromHours(2));
+        var result = dateTimeOffset.TryConvertTo<DateTime>();
+        Assert.IsTrue(result.Success);
+        Assert.Multiple(() =>
+        {
+            Assert.AreEqual(new DateTime(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03)), result.Result);
+            Assert.AreEqual(DateTimeKind.Utc, result.Result.Kind);
+        });
+    }
+
+    [Test]
+    public void DiscardsDateTimeKindWhenConvertingDateTimeToDateTimeOffset()
+    {
+        var dateTime = new DateTime(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03), DateTimeKind.Local);
+        var result = dateTime.TryConvertTo<DateTimeOffset>();
+        Assert.IsTrue(result.Success);
+        Assert.AreEqual(new DateTimeOffset(new DateOnly(2024, 07, 05), new TimeOnly(12, 30, 01, 02, 03), TimeSpan.Zero), result.Result);
+    }
+
     [Test]
     public void Value_Editor_Can_Convert_Decimal_To_Decimal_Clr_Type()
     {
@@ -342,6 +387,23 @@
         Assert.AreEqual(12.34d, result.Result);
     }
 
+    [Test]
+    public void Value_Editor_Can_Convert_DateTimeOffset_To_DateTime_Clr_Type()
+    {
+        var valueEditor = MockedValueEditors.CreateDataValueEditor(ValueTypes.Date);
+
+        var result = valueEditor.TryConvertValueToCrlType(new DateTimeOffset(new DateOnly(2024, 07, 05), new TimeOnly(12, 30), TimeSpan.Zero));
+        Assert.IsTrue(result.Success);
+        Assert.IsTrue(result.Result is DateTime);
+
+        var dateTime = (DateTime)result.Result;
+        Assert.Multiple(() =>
+        {
+            Assert.AreEqual(new DateTime(new DateOnly(2024, 07, 05), new TimeOnly(12, 30)), dateTime);
+            Assert.AreEqual(DateTimeKind.Utc, dateTime.Kind);
+        });
+    }
+
     private class MyTestObject
     {
         public override string ToString() => "Hello world";