From ad5c9e2017368e80cd93d5a9c3fc5e426d1b2651 Mon Sep 17 00:00:00 2001
From: Stephen Dahlke <stephen.dahlke@dojo.tech>
Date: Fri, 5 Dec 2025 17:11:07 +0000
Subject: [PATCH] fix: apply DateTime to DATE mapping

---
 .../Storage/Internal/SpannerDateDateTimeTypeMapping.cs | 10 ++++++++++
 .../Storage/Internal/SpannerDateTypeMapping.cs         |  9 ++++++++-
 .../Storage/Internal/SpannerTypeMappingSource.cs       |  7 +++++++
 3 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateDateTimeTypeMapping.cs

diff --git a/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateDateTimeTypeMapping.cs b/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateDateTimeTypeMapping.cs
new file mode 100644
index 00000000..8c271dc2
--- /dev/null
+++ b/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateDateTimeTypeMapping.cs
@@ -0,0 +1,10 @@
+using System;
+
+namespace Google.Cloud.EntityFrameworkCore.Spanner.Storage.Internal;
+
+internal class SpannerDateDateTimeTypeMapping : SpannerDateTypeMapping
+{
+    public SpannerDateDateTimeTypeMapping() : base(typeof(DateTime))
+    {
+    }
+}
\ No newline at end of file
diff --git a/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateTypeMapping.cs b/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateTypeMapping.cs
index 42cd7ed9..d60dfb17 100644
--- a/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateTypeMapping.cs
+++ b/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerDateTypeMapping.cs
@@ -25,8 +25,15 @@ internal class SpannerDateTypeMapping : RelationalTypeMapping
             v => SpannerDate.FromDateTime(v));
 
         public SpannerDateTypeMapping()
+            : this(typeof(SpannerDate))
+        { }
+
+        protected SpannerDateTypeMapping(System.Type clrType)
             : base(new RelationalTypeMappingParameters(
-                   new CoreTypeMappingParameters(typeof(SpannerDate), s_converter),
+                   new CoreTypeMappingParameters(clrType,
+                       // use converter only for SpannerDate; DateTime maps directly
+                       clrType == typeof(SpannerDate) ? s_converter : null
+                       ),
                    "DATE", StoreTypePostfix.None, System.Data.DbType.Date))
         { }
 
diff --git a/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerTypeMappingSource.cs b/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerTypeMappingSource.cs
index 9b00beeb..31019b48 100644
--- a/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerTypeMappingSource.cs
+++ b/Google.Cloud.EntityFrameworkCore.Spanner/Storage/Internal/SpannerTypeMappingSource.cs
@@ -38,6 +38,7 @@ private static readonly BoolTypeMapping s_bool
             = new SpannerBoolTypeMapping(SpannerDbType.Bool.ToString());
 
         private static readonly SpannerDateTypeMapping s_date = new SpannerDateTypeMapping();
+        private static readonly SpannerDateDateTimeTypeMapping s_dateTimeDate = new SpannerDateDateTimeTypeMapping();
         
         private static readonly SpannerDateOnlyTypeMapping s_dateonly = new ();
 
@@ -327,6 +328,12 @@ private RelationalTypeMapping FindRawMapping(RelationalTypeMappingInfo mappingIn
                 if (_storeTypeMappings.TryGetValue(storeTypeName, out var mapping)
                     || _storeTypeMappings.TryGetValue(storeTypeNameBase, out mapping))
                 {
+                    // if DateTime is being used to map to DATE we need to use the default DateTime<>DateTime mapping instead of trying to use DateTime<>SpannerDate
+                    if (mapping == s_date && clrType == typeof(DateTime))
+                    {
+                        return s_dateTimeDate;
+                    }
+
                     if (clrType == null
                         || mapping.ClrType == clrType
                         || mapping.Converter?.ProviderClrType == clrType)