Fix C# + C++ SDKs for making Options filterable and expand sdk-test

crates/bindings-cpp/include/spacetimedb/table_with_constraints.h

@@ -210,21 +210,30 @@ struct MultiColumnIndexTag {
 // Constraint Concepts
 // =============================================================================
 
+namespace detail {
+    template<typename T>
+    struct filterable_value_impl
+        : std::bool_constant<
+              std::integral<T> ||
+              std::same_as<T, std::string> ||
+              std::same_as<T, SpacetimeDB::Identity> ||
+              std::same_as<T, SpacetimeDB::ConnectionId> ||
+              std::same_as<T, SpacetimeDB::Timestamp> ||
+              std::same_as<T, SpacetimeDB::Uuid> ||
+              std::same_as<T, SpacetimeDB::I128> ||
+              std::same_as<T, SpacetimeDB::U128> ||
+              std::same_as<T, SpacetimeDB::I256> ||
+              std::same_as<T, SpacetimeDB::U256> ||
+              std::same_as<T, SpacetimeDB::i256> ||
+              std::same_as<T, SpacetimeDB::u256> ||
+              std::is_enum_v<T>> {};
+
+    template<typename T>
+    struct filterable_value_impl<std::optional<T>> : filterable_value_impl<std::remove_cvref_t<T>> {};
+}
+
 template<typename T>
-concept FilterableValue = 
-    std::integral<T> ||
-    std::same_as<T, std::string> ||
-    std::same_as<T, SpacetimeDB::Identity> ||
-    std::same_as<T, SpacetimeDB::ConnectionId> ||
-    std::same_as<T, SpacetimeDB::Timestamp> ||
-    std::same_as<T, SpacetimeDB::Uuid> ||
-    std::same_as<T, SpacetimeDB::I128> ||
-    std::same_as<T, SpacetimeDB::U128> ||
-    std::same_as<T, SpacetimeDB::I256> ||
-    std::same_as<T, SpacetimeDB::U256> ||
-    std::same_as<T, SpacetimeDB::i256> ||
-    std::same_as<T, SpacetimeDB::u256> ||
-    std::is_enum_v<T>;
+concept FilterableValue = detail::filterable_value_impl<std::remove_cvref_t<T>>::value;
 
 template<typename T>
 concept AutoIncrementable = 

crates/bindings-csharp/Codegen.Tests/Tests.cs

@@ -379,6 +379,33 @@ public static void TestNullableBTreeIndex(ReducerContext ctx)
                     _ = ctx.Db.NullableBTreeIndex.AccountId.Filter(new Bound<uint?>(null, 99));
                 }
             }
+
+            [SpacetimeDB.Table]
+            public partial struct NullableUniqueIndex
+            {
+                [SpacetimeDB.PrimaryKey]
+                public uint Id;
+
+                [SpacetimeDB.Unique]
+                public uint? AccountId;
+
+                [SpacetimeDB.Unique]
+                public string? Name;
+
+                [SpacetimeDB.Unique]
+                public SpacetimeDB.Uuid? ExternalId;
+
+                [SpacetimeDB.Reducer]
+                public static void TestNullableUniqueIndex(ReducerContext ctx)
+                {
+                    _ = ctx.Db.NullableUniqueIndex.AccountId.Find((uint?)null);
+                    _ = ctx.Db.NullableUniqueIndex.AccountId.Find((uint?)55);
+                    _ = ctx.Db.NullableUniqueIndex.Name.Find((string?)null);
+                    _ = ctx.Db.NullableUniqueIndex.Name.Find("name");
+                    _ = ctx.Db.NullableUniqueIndex.ExternalId.Find((SpacetimeDB.Uuid?)null);
+                    _ = ctx.Db.NullableUniqueIndex.ExternalId.Find(SpacetimeDB.Uuid.NIL);
+                }
+            }
             """;
 
         var parseOptions = new CSharpParseOptions(fixture.SampleCompilation.LanguageVersion);

crates/bindings-csharp/Codegen/Module.cs

@@ -160,9 +160,22 @@ public static bool IsNoPayloadEnum(ITypeSymbol type)
             && variants.All(field => field.Type.ToString() == "SpacetimeDB.Unit");
     }
 
-    public static bool IsEquatable(ITypeSymbol type) =>
-        (
-            IsInteger(type)
+    private static ITypeSymbol UnwrapNullable(ITypeSymbol type) =>
+        type switch
+        {
+            INamedTypeSymbol
+            {
+                OriginalDefinition.SpecialType: SpecialType.System_Nullable_T
+            } nullable => nullable.TypeArguments[0],
+            _ when type.NullableAnnotation == NullableAnnotation.Annotated =>
+                type.WithNullableAnnotation(NullableAnnotation.None),
+            _ => type,
+        };
+
+    public static bool IsEquatable(ITypeSymbol type)
+    {
+        type = UnwrapNullable(type);
+        return IsInteger(type)
             || IsNoPayloadEnum(type)
             || type.SpecialType switch
             {
@@ -173,9 +186,8 @@ public static bool IsEquatable(ITypeSymbol type) =>
                         or "SpacetimeDB.Timestamp"
                         or "SpacetimeDB.Uuid",
                 _ => false,
-            }
-        )
-        && type.NullableAnnotation != NullableAnnotation.Annotated;
+            };
+    }
 }
 
 /// <summary>

crates/codegen/src/csharp.rs

@@ -561,10 +561,12 @@ impl Lang for Csharp<'_> {
                         (csharp_field_name_pascal, csharp_field_type)
                     };
 
-                    let (row_to_key, key_type) = match columns.as_singleton() {
+                    let (row_to_key, key_type, nullable_single_column) = match columns.as_singleton() {
                         Some(col_pos) => {
                             let (field_name, field_type) = get_csharp_field_name_and_type(col_pos);
-                            (format!("row.{field_name}"), field_type.to_string())
+                            let field_type = field_type.to_string();
+                            let nullable_single_column = field_type.ends_with('?');
+                            (format!("row.{field_name}"), field_type, nullable_single_column)
                         }
                         None => {
                             let mut key_accessors = Vec::new();
@@ -576,6 +578,7 @@ impl Lang for Csharp<'_> {
                             (
                                 format!("({})", key_accessors.join(", ")),
                                 format!("({})", key_type_elems.join(", ")),
+                                false,
                             )
                         }
                     };
@@ -585,10 +588,18 @@ impl Lang for Csharp<'_> {
                     let mut csharp_index_class_name = csharp_index_name.clone();
                     let csharp_index_base_class_name = if schema.is_unique(&columns) {
                         csharp_index_class_name += "UniqueIndex";
-                        "UniqueIndexBase"
+                        if nullable_single_column {
+                            "NullableUniqueIndexBase"
+                        } else {
+                            "UniqueIndexBase"
+                        }
                     } else {
                         csharp_index_class_name += "Index";
-                        "BTreeIndexBase"
+                        if nullable_single_column {
+                            "NullableBTreeIndexBase"
+                        } else {
+                            "BTreeIndexBase"
+                        }
                     };
 
                     writeln!(