Fix issues with nulls in primitive collections

src/EFCore.Relational/Query/SqlNullabilityProcessor.cs

@@ -1921,7 +1921,11 @@ protected virtual bool TryMakeNonNullable(
                 {
                     if (processedValues is null)
                     {
-                        var elementClrType = values.GetType().GetSequenceType();
+                        // We found the first null value - we need to start copying values to a new list which will be used for the rewritten parameter.
+                        // The type of the new list must match that of the original enumerable parameter, as there may be value converters involved which
+                        // rely on the precise element type (see #37605). We therefore get the type of the element from the original list if it implements
+                        // IEnumerable<T>, or default to object.
+                        var elementClrType = enumerable.GetType().TryGetElementType(typeof(IEnumerable<>)) ?? typeof(object);
                         processedValues = (IList)Activator.CreateInstance(typeof(List<>).MakeGenericType(elementClrType), values.Count)!;
                         for (var j = 0; j < i; j++)
                         {

src/EFCore.SqlServer/Query/Internal/SqlServerSqlNullabilityProcessor.cs

@@ -36,7 +36,6 @@ public class SqlServerSqlNullabilityProcessor(
     private int _openJsonAliasCounter;
     private int _totalParameterCount;
 
-
     /// <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
@@ -300,6 +299,7 @@ protected override SqlExpression VisitIn(InExpression inExpression, bool allowOp
             {
                 Check.DebugAssert(valuesParameter.TypeMapping is not null);
                 Check.DebugAssert(valuesParameter.TypeMapping.ElementTypeMapping is not null);
+
                 var elementTypeMapping = (RelationalTypeMapping)valuesParameter.TypeMapping.ElementTypeMapping;
 
                 if (TryHandleOverLimitParameters(
@@ -325,7 +325,7 @@ protected override SqlExpression VisitIn(InExpression inExpression, bool allowOp
                                             new ColumnExpression(
                                                 columnName,
                                                 openJson.Alias,
-                                                valuesParameter.Type.GetSequenceType(),
+                                                valuesParameter.Type.GetSequenceType().UnwrapNullableType(),
                                                 elementTypeMapping,
                                                 containsNulls!.Value),
                                             columnName)

test/EFCore.Cosmos.FunctionalTests/Query/PrimitiveCollectionsQueryCosmosTest.cs

@@ -713,6 +713,20 @@ WHERE NOT(ARRAY_CONTAINS(@nullableInts, c["NullableInt"]))
 """);
     }
 
+    public override async Task Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter()
+    {
+        await base.Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter();
+
+        AssertSql(
+            """
+@nullableInts='[null,999]'
+
+SELECT VALUE c
+FROM root c
+WHERE ARRAY_CONTAINS(@nullableInts, c["NullableInt"])
+""");
+    }
+
     public override async Task Parameter_collection_of_strings_Contains_string()
     {
         await base.Parameter_collection_of_strings_Contains_string();

test/EFCore.Specification.Tests/Query/PrimitiveCollectionsQueryTestBase.cs

@@ -345,6 +345,16 @@ public virtual async Task Parameter_collection_of_nullable_ints_Contains_nullabl
         await AssertQuery(ss => ss.Set<PrimitiveCollectionsEntity>().Where(c => !nullableInts.Contains(c.NullableInt)));
     }
 
+    [ConditionalFact] // #37605
+    public virtual async Task Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter()
+    {
+        var nullableInts = new int?[] { null, 999 };
+
+        await AssertQuery(
+            ss => ss.Set<PrimitiveCollectionsEntity>().Where(c => EF.Parameter(nullableInts).Contains(c.NullableInt)),
+            ss => ss.Set<PrimitiveCollectionsEntity>().Where(c => nullableInts.Contains(c.NullableInt)));
+    }
+
     [ConditionalFact]
     public virtual async Task Parameter_collection_of_structs_Contains_struct()
     {

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

@@ -695,6 +695,14 @@ WHERE [p].[NullableInt] IS NOT NULL AND [p].[NullableInt] <> @nullableInts1
 """);
     }
 
+    public override async Task Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter()
+    {
+        // EF.Parameter() on primitive collection (OPENJSON on SQL Server) not supported on old versions of SQL Server.
+        await Assert.ThrowsAsync<InvalidOperationException>(base.Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter);
+
+        AssertSql();
+    }
+
     public override async Task Parameter_collection_of_strings_Contains_string()
     {
         await base.Parameter_collection_of_strings_Contains_string();
@@ -1806,6 +1814,19 @@ SELECT COUNT(*)
 """);
     }
 
+    [ConditionalFact] // #37605
+    public virtual async Task Parameter_collection_with_null_value_Contains_null_2201_values()
+    {
+        using var context = Fixture.CreateContext();
+
+        var values = Enumerable.Range(1, 2200).Select(i => (int?)i).ToList();
+        values.Add(null);
+
+        await AssertQuery(ss => ss.Set<PrimitiveCollectionsEntity>().Where(e => values.Contains(e.NullableInt)));
+
+        // No SQL assertion as the SQL is huge
+    }
+
     [ConditionalFact]
     public virtual void Check_all_tests_overridden()
         => TestHelpers.AssertAllMethodsOverridden(GetType());

test/EFCore.SqlServer.FunctionalTests/Query/PrimitiveCollectionsQuerySqlServer160Test.cs

@@ -703,6 +703,23 @@ WHERE [p].[NullableInt] IS NOT NULL AND [p].[NullableInt] <> @nullableInts1
 """);
     }
 
+    public override async Task Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter()
+    {
+        await base.Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter();
+
+        AssertSql(
+            """
+@nullableInts_without_nulls='[999]' (Size = 4000)
+
+SELECT [p].[Id], [p].[Bool], [p].[Bools], [p].[DateTime], [p].[DateTimes], [p].[Enum], [p].[Enums], [p].[Int], [p].[Ints], [p].[NullableInt], [p].[NullableInts], [p].[NullableString], [p].[NullableStrings], [p].[NullableWrappedId], [p].[NullableWrappedIdWithNullableComparer], [p].[String], [p].[Strings], [p].[WrappedId]
+FROM [PrimitiveCollectionsEntity] AS [p]
+WHERE [p].[NullableInt] IN (
+    SELECT [n].[value]
+    FROM OPENJSON(@nullableInts_without_nulls) AS [n]
+) OR [p].[NullableInt] IS NULL
+""");
+    }
+
     public override async Task Parameter_collection_of_strings_Contains_string()
     {
         await base.Parameter_collection_of_strings_Contains_string();

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

@@ -872,6 +872,23 @@ WHERE [p].[NullableInt] IS NOT NULL AND [p].[NullableInt] <> @nullableInts1
 """);
     }
 
+    public override async Task Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter()
+    {
+        await base.Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter();
+
+        AssertSql(
+            """
+@nullableInts_without_nulls='[999]' (Size = 5)
+
+SELECT [p].[Id], [p].[Bool], [p].[Bools], [p].[DateTime], [p].[DateTimes], [p].[Enum], [p].[Enums], [p].[Int], [p].[Ints], [p].[NullableInt], [p].[NullableInts], [p].[NullableString], [p].[NullableStrings], [p].[NullableWrappedId], [p].[NullableWrappedIdWithNullableComparer], [p].[String], [p].[Strings], [p].[WrappedId]
+FROM [PrimitiveCollectionsEntity] AS [p]
+WHERE [p].[NullableInt] IN (
+    SELECT [n].[value]
+    FROM OPENJSON(@nullableInts_without_nulls) AS [n]
+) OR [p].[NullableInt] IS NULL
+""");
+    }
+
     public override async Task Parameter_collection_of_structs_Contains_struct()
     {
         await base.Parameter_collection_of_structs_Contains_struct();

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

@@ -726,6 +726,23 @@ WHERE [p].[NullableInt] IS NOT NULL AND [p].[NullableInt] <> @nullableInts1
 """);
     }
 
+    public override async Task Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter()
+    {
+        await base.Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter();
+
+        AssertSql(
+            """
+@nullableInts_without_nulls='[999]' (Size = 4000)
+
+SELECT [p].[Id], [p].[Bool], [p].[Bools], [p].[DateTime], [p].[DateTimes], [p].[Enum], [p].[Enums], [p].[Int], [p].[Ints], [p].[NullableInt], [p].[NullableInts], [p].[NullableString], [p].[NullableStrings], [p].[NullableWrappedId], [p].[NullableWrappedIdWithNullableComparer], [p].[String], [p].[Strings], [p].[WrappedId]
+FROM [PrimitiveCollectionsEntity] AS [p]
+WHERE [p].[NullableInt] IN (
+    SELECT [n].[value]
+    FROM OPENJSON(@nullableInts_without_nulls) AS [n]
+) OR [p].[NullableInt] IS NULL
+""");
+    }
+
     public override async Task Parameter_collection_of_strings_Contains_string()
     {
         await base.Parameter_collection_of_strings_Contains_string();
@@ -2568,6 +2585,19 @@ SELECT COUNT(*)
 """);
     }
 
+    [ConditionalFact] // #37605
+    public virtual async Task Parameter_collection_with_null_value_Contains_null_2201_values()
+    {
+        using var context = Fixture.CreateContext();
+
+        var values = Enumerable.Range(1, 2200).Select(i => (int?)i).ToList();
+        values.Add(null);
+
+        await AssertQuery(ss => ss.Set<PrimitiveCollectionsEntity>().Where(e => values.Contains(e.NullableInt)));
+
+        // No SQL assertion as the SQL is huge
+    }
+
     [ConditionalFact]
     public virtual async Task Parameter_collection_of_ints_Contains_int_2071_values()
     {

test/EFCore.Sqlite.FunctionalTests/Query/PrimitiveCollectionsQuerySqliteTest.cs

@@ -714,6 +714,23 @@ public override async Task Parameter_collection_of_nullable_ints_Contains_nullab
 """);
     }
 
+    public override async Task Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter()
+    {
+        await base.Parameter_collection_of_nullable_ints_Contains_nullable_int_with_EF_Parameter();
+
+        AssertSql(
+            """
+@nullableInts_without_nulls='[999]' (Size = 5)
+
+SELECT "p"."Id", "p"."Bool", "p"."Bools", "p"."DateTime", "p"."DateTimes", "p"."Enum", "p"."Enums", "p"."Int", "p"."Ints", "p"."NullableInt", "p"."NullableInts", "p"."NullableString", "p"."NullableStrings", "p"."NullableWrappedId", "p"."NullableWrappedIdWithNullableComparer", "p"."String", "p"."Strings", "p"."WrappedId"
+FROM "PrimitiveCollectionsEntity" AS "p"
+WHERE "p"."NullableInt" IN (
+    SELECT "n"."value"
+    FROM json_each(@nullableInts_without_nulls) AS "n"
+) OR "p"."NullableInt" IS NULL
+""");
+    }
+
     public override async Task Parameter_collection_of_strings_Contains_string()
     {
         await base.Parameter_collection_of_strings_Contains_string();