Fix NTS geometries stored as invalid geographies in SQL Server

src/EFCore.SqlServer.NTS/Storage/ValueConversion/Internal/GeometryValueConverter.cs

@@ -16,6 +16,14 @@ namespace Microsoft.EntityFrameworkCore.SqlServer.Storage.ValueConversion.Intern
 public class GeometryValueConverter<TGeometry> : ValueConverter<TGeometry, SqlBytes>
     where TGeometry : Geometry
 {
+    // The IsValid flag is at bit 2 (0x04) of the Properties byte at offset 5 in the SQL Server
+    // geography/geometry binary format (MS-SSCLRT). SqlServerBytesWriter sets this flag based on
+    // NTS's Geometry.IsValid, but NTS and SQL Server use different validation rules. We always set
+    // this flag to true to avoid NTS validation rules incorrectly marking geometries as invalid
+    // in SQL Server. See https://github.com/dotnet/efcore/issues/37416
+    private const int PropertiesByteIndex = 5;
+    private const byte IsValidFlag = 0x04;
+
     /// <summary>
     ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
     ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
@@ -24,8 +32,18 @@ public class GeometryValueConverter<TGeometry> : ValueConverter<TGeometry, SqlBy
     /// </summary>
     public GeometryValueConverter(SqlServerBytesReader reader, SqlServerBytesWriter writer)
         : base(
-            g => new SqlBytes(writer.Write(g)),
+            g => new SqlBytes(SetIsValidFlag(writer.Write(g))),
             b => (TGeometry)reader.Read(b.Value))
     {
     }
+
+    private static byte[] SetIsValidFlag(byte[] bytes)
+    {
+        if (bytes.Length > PropertiesByteIndex)
+        {
+            bytes[PropertiesByteIndex] |= IsValidFlag;
+        }
+
+        return bytes;
+    }
 }

test/EFCore.SqlServer.Tests/Storage/ValueConversion/Internal/GeometryValueConverterTest.cs

@@ -0,0 +1,108 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Data.SqlTypes;
+using NetTopologySuite;
+using NetTopologySuite.Geometries;
+using NetTopologySuite.IO;
+
+namespace Microsoft.EntityFrameworkCore.SqlServer.Storage.ValueConversion.Internal;
+
+public class GeometryValueConverterTest
+{
+    // The IsValid flag is at bit 2 (0x04) of the Properties byte at offset 5 in the SQL Server
+    // geography/geometry binary format (MS-SSCLRT).
+    private const int PropertiesByteIndex = 5;
+    private const byte IsValidFlag = 0x04;
+
+    [ConditionalFact]
+    public void IsValid_flag_set_for_valid_geometry()
+    {
+        var point = new Point(1, 2) { SRID = 4326 };
+        Assert.True(point.IsValid);
+
+        var converter = CreateConverter(isGeography: false);
+        var sqlBytes = (SqlBytes)converter.ConvertToProvider(point)!;
+
+        Assert.True((sqlBytes.Value[PropertiesByteIndex] & IsValidFlag) != 0, "IsValid flag should be set for valid geometry");
+    }
+
+    [ConditionalFact]
+    public void IsValid_flag_set_for_valid_geography()
+    {
+        var point = new Point(1, 2) { SRID = 4326 };
+        Assert.True(point.IsValid);
+
+        var converter = CreateConverter(isGeography: true);
+        var sqlBytes = (SqlBytes)converter.ConvertToProvider(point)!;
+
+        Assert.True((sqlBytes.Value[PropertiesByteIndex] & IsValidFlag) != 0, "IsValid flag should be set for valid geography");
+    }
+
+    [ConditionalFact]
+    public void IsValid_flag_set_for_invalid_geometry()
+    {
+        // Create an invalid geometry (self-intersecting polygon - bowtie shape)
+        var polygon = new Polygon(
+            new LinearRing(
+            [
+                new Coordinate(0, 0),
+                new Coordinate(2, 2),
+                new Coordinate(2, 0),
+                new Coordinate(0, 2),
+                new Coordinate(0, 0)
+            ]));
+        Assert.False(polygon.IsValid);
+
+        var converter = CreateConverter(isGeography: false);
+        var sqlBytes = (SqlBytes)converter.ConvertToProvider(polygon)!;
+
+        Assert.True(
+            (sqlBytes.Value[PropertiesByteIndex] & IsValidFlag) != 0,
+            "IsValid flag should be set even for NTS-invalid geometry");
+    }
+
+    [ConditionalFact]
+    public void IsValid_flag_set_for_invalid_geography()
+    {
+        // Create an invalid geography (self-intersecting polygon - bowtie shape)
+        var polygon = new Polygon(
+            new LinearRing(
+            [
+                new Coordinate(0, 0),
+                new Coordinate(2, 2),
+                new Coordinate(2, 0),
+                new Coordinate(0, 2),
+                new Coordinate(0, 0)
+            ])) { SRID = 4326 };
+        Assert.False(polygon.IsValid);
+
+        var converter = CreateConverter(isGeography: true);
+        var sqlBytes = (SqlBytes)converter.ConvertToProvider(polygon)!;
+
+        Assert.True(
+            (sqlBytes.Value[PropertiesByteIndex] & IsValidFlag) != 0,
+            "IsValid flag should be set even for NTS-invalid geography");
+    }
+
+    [ConditionalFact]
+    public void Roundtrip_preserves_geometry_data()
+    {
+        var point = new Point(1, 2) { SRID = 4326 };
+
+        var converter = CreateConverter(isGeography: false);
+        var sqlBytes = (SqlBytes)converter.ConvertToProvider(point)!;
+        var roundtripped = (Point)converter.ConvertFromProvider(sqlBytes)!;
+
+        Assert.Equal(point.X, roundtripped.X);
+        Assert.Equal(point.Y, roundtripped.Y);
+        Assert.Equal(point.SRID, roundtripped.SRID);
+    }
+
+    private static GeometryValueConverter<Geometry> CreateConverter(bool isGeography)
+    {
+        var reader = new SqlServerBytesReader(NtsGeometryServices.Instance) { IsGeography = isGeography };
+        var writer = new SqlServerBytesWriter { IsGeography = isGeography };
+        return new GeometryValueConverter<Geometry>(reader, writer);
+    }
+}