[release/7.0] Fix to #30996 - Incorrect translation of comparison of current value with owned type default value

src/EFCore.Relational/Query/RelationalSqlTranslatingExpressionVisitor.cs

@@ -20,6 +20,9 @@ namespace Microsoft.EntityFrameworkCore.Query;
 /// </summary>
 public class RelationalSqlTranslatingExpressionVisitor : ExpressionVisitor
 {
+    private static readonly bool UseOldBehavior30996
+        = AppContext.TryGetSwitch("Microsoft.EntityFrameworkCore.Issue30996", out var enabled30996) && enabled30996;
+
     private const string RuntimeParameterPrefix = QueryCompilationContext.QueryParameterPrefix + "entity_equality_";
 
     private static readonly List<MethodInfo> SingleResultMethodInfos = new()
@@ -1671,19 +1674,33 @@ private bool TryRewriteEntityEquality(
                     if (allNonPrincipalSharedNonPkProperties.Count != 0
                         && allNonPrincipalSharedNonPkProperties.All(p => p.IsNullable))
                     {
-                        var atLeastOneNonNullValueInNullablePropertyCondition = allNonPrincipalSharedNonPkProperties
-                            .Select(
-                                p => Infrastructure.ExpressionExtensions.CreateEqualsExpression(
-                                    CreatePropertyAccessExpression(nonNullEntityReference, p),
-                                    Expression.Constant(null, p.ClrType.MakeNullable()),
-                                    nodeType != ExpressionType.Equal))
-                            .Aggregate((l, r) => nodeType == ExpressionType.Equal ? Expression.OrElse(l, r) : Expression.AndAlso(l, r));
+                        Expression? optionalPropertiesCondition;
+                        if (!UseOldBehavior30996)
+                        {
+                            optionalPropertiesCondition = allNonPrincipalSharedNonPkProperties
+                                .Select(
+                                    p => Infrastructure.ExpressionExtensions.CreateEqualsExpression(
+                                        CreatePropertyAccessExpression(nonNullEntityReference, p),
+                                        Expression.Constant(null, p.ClrType.MakeNullable()),
+                                        nodeType != ExpressionType.Equal))
+                                .Aggregate((l, r) => nodeType == ExpressionType.Equal ? Expression.AndAlso(l, r) : Expression.OrElse(l, r));
+                        }
+                        else
+                        {
+                            optionalPropertiesCondition = allNonPrincipalSharedNonPkProperties
+                                .Select(
+                                    p => Infrastructure.ExpressionExtensions.CreateEqualsExpression(
+                                        CreatePropertyAccessExpression(nonNullEntityReference, p),
+                                        Expression.Constant(null, p.ClrType.MakeNullable()),
+                                        nodeType != ExpressionType.Equal))
+                                .Aggregate((l, r) => nodeType == ExpressionType.Equal ? Expression.OrElse(l, r) : Expression.AndAlso(l, r));
+                        }
 
                         condition = condition == null
-                            ? atLeastOneNonNullValueInNullablePropertyCondition
+                            ? optionalPropertiesCondition
                             : nodeType == ExpressionType.Equal
-                                ? Expression.OrElse(condition, atLeastOneNonNullValueInNullablePropertyCondition)
-                                : Expression.AndAlso(condition, atLeastOneNonNullValueInNullablePropertyCondition);
+                                ? Expression.OrElse(condition, optionalPropertiesCondition)
+                                : Expression.AndAlso(condition, optionalPropertiesCondition);
                     }
 
                     if (condition != null)

test/EFCore.Relational.Specification.Tests/Query/OwnedEntityQueryRelationalTestBase.cs

@@ -284,6 +284,64 @@ public virtual async Task Owned_entity_with_all_null_properties_entity_equality_
             });
     }
 
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual async Task Owned_entity_with_all_null_properties_in_compared_to_null_in_conditional_projection(bool async)
+    {
+        var contextFactory = await InitializeAsync<MyContext28247>(seed: c => c.Seed());
+
+        using var context = contextFactory.CreateContext();
+        var query = context.RotRutCases
+            .AsNoTracking()
+            .OrderBy(e => e.Id)
+            .Select(e => e.Rot == null ? null : new RotDto { MyApartmentNo = e.Rot.ApartmentNo, MyServiceType = e.Rot.ServiceType });
+
+        var result = async
+            ? await query.ToListAsync()
+            : query.ToList();
+
+        Assert.Collection(
+            result,
+            t =>
+            {
+                Assert.Equal("1", t.MyApartmentNo);
+                Assert.Equal(1, t.MyServiceType);
+            },
+            t =>
+            {
+                Assert.Null(t);
+            });
+    }
+
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual async Task Owned_entity_with_all_null_properties_in_compared_to_non_null_in_conditional_projection(bool async)
+    {
+        var contextFactory = await InitializeAsync<MyContext28247>(seed: c => c.Seed());
+
+        using var context = contextFactory.CreateContext();
+        var query = context.RotRutCases
+            .AsNoTracking()
+            .OrderBy(e => e.Id)
+            .Select(e => e.Rot != null ? new RotDto { MyApartmentNo = e.Rot.ApartmentNo, MyServiceType = e.Rot.ServiceType } : null);
+
+        var result = async
+            ? await query.ToListAsync()
+            : query.ToList();
+
+        Assert.Collection(
+            result,
+            t =>
+            {
+                Assert.Equal("1", t.MyApartmentNo);
+                Assert.Equal(1, t.MyServiceType);
+            },
+            t =>
+            {
+                Assert.Null(t);
+            });
+    }
+
     [ConditionalTheory]
     [MemberData(nameof(IsAsyncData))]
     public virtual async Task Owned_entity_with_all_null_properties_property_access_when_not_containing_another_owned_entity(bool async)
@@ -364,6 +422,12 @@ public class Rot
         public string ApartmentNo { get; set; }
     }
 
+    public class RotDto
+    {
+        public int? MyServiceType { get; set; }
+        public string MyApartmentNo { get; set; }
+    }
+
     public class Rut
     {
         public int? Value { get; set; }

test/EFCore.SqlServer.FunctionalTests/Query/OwnedEntityQuerySqlServerTest.cs

@@ -166,7 +166,37 @@ public override async Task Owned_entity_with_all_null_properties_entity_equality
 """
 SELECT [r].[Id], [r].[Rot_ApartmentNo], [r].[Rot_ServiceType]
 FROM [RotRutCases] AS [r]
-WHERE ([r].[Rot_ApartmentNo] IS NOT NULL) AND ([r].[Rot_ServiceType] IS NOT NULL)
+WHERE ([r].[Rot_ApartmentNo] IS NOT NULL) OR ([r].[Rot_ServiceType] IS NOT NULL)
+""");
+    }
+
+    public override async Task Owned_entity_with_all_null_properties_in_compared_to_null_in_conditional_projection(bool async)
+    {
+        await base.Owned_entity_with_all_null_properties_in_compared_to_null_in_conditional_projection(async);
+
+        AssertSql(
+"""
+SELECT CASE
+    WHEN ([r].[Rot_ApartmentNo] IS NULL) AND ([r].[Rot_ServiceType] IS NULL) THEN CAST(1 AS bit)
+    ELSE CAST(0 AS bit)
+END, [r].[Rot_ApartmentNo], [r].[Rot_ServiceType]
+FROM [RotRutCases] AS [r]
+ORDER BY [r].[Id]
+""");
+    }
+
+    public override async Task Owned_entity_with_all_null_properties_in_compared_to_non_null_in_conditional_projection(bool async)
+    {
+        await base.Owned_entity_with_all_null_properties_in_compared_to_non_null_in_conditional_projection(async);
+
+        AssertSql(
+"""
+SELECT CASE
+    WHEN ([r].[Rot_ApartmentNo] IS NOT NULL) OR ([r].[Rot_ServiceType] IS NOT NULL) THEN CAST(1 AS bit)
+    ELSE CAST(0 AS bit)
+END, [r].[Rot_ApartmentNo], [r].[Rot_ServiceType]
+FROM [RotRutCases] AS [r]
+ORDER BY [r].[Id]
 """);
     }