Fix missing | None for nullable enum literals in TypedDict (#2991)

* Fix missing | None for nullable enum literals in TypedDict

* Update expected output for MultipleTypeEnum with | None

* Guard against all-None enums producing empty Literal

* Remove unreachable empty-literal guard

Author: koxudaxi

src/datamodel_code_generator/parser/jsonschema.py

@@ -3527,7 +3527,10 @@ def _parse_multiple_types_with_properties(
 
     def parse_enum_as_literal(self, obj: JsonSchemaObject) -> DataType:
         """Parse enum values as a Literal type."""
-        return self.data_type(literals=[i for i in obj.enum if i is not None])
+        return self.data_type(
+            literals=[i for i in obj.enum if i is not None],
+            is_optional=None in obj.enum,
+        )
 
     @classmethod
     def _get_field_name_from_dict_enum(cls, enum_part: dict[str, Any], index: int) -> str:

tests/data/expected/main/jsonschema/typed_dict_nullable_enum_literal.py

@@ -0,0 +1,15 @@
+# generated by datamodel-codegen:
+#   filename:  nullable_enum_literal_typed_dict.json
+#   timestamp: 2019-07-26T00:00:00+00:00
+
+from __future__ import annotations
+
+from typing import Literal, NotRequired, TypeAlias, TypedDict
+
+StatusEnum: TypeAlias = Literal['active', 'inactive'] | None
+
+
+class Record(TypedDict):
+    required_inline: Literal['active', 'inactive'] | None
+    required_ref: StatusEnum
+    optional_inline: NotRequired[Literal['pending', 'completed'] | None]

tests/data/expected/main/openapi/enum_models/all.py

@@ -49,7 +49,7 @@ class AliasEnum(BaseModel):
 
 
 class MultipleTypeEnum(BaseModel):
-    __root__: Literal['red', 'amber', 'green', 42]
+    __root__: Literal['red', 'amber', 'green', 42] | None
 
 
 class SingleEnum(BaseModel):

tests/data/expected/main/openapi/enum_models/as_literal.py

@@ -49,7 +49,7 @@ class AliasEnum(BaseModel):
 
 
 class MultipleTypeEnum(BaseModel):
-    __root__: Literal['red', 'amber', 'green', 42]
+    __root__: Literal['red', 'amber', 'green', 42] | None
 
 
 class SingleEnum(BaseModel):

tests/data/jsonschema/nullable_enum_literal_typed_dict.json

@@ -0,0 +1,25 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "Record",
+  "type": "object",
+  "definitions": {
+    "StatusEnum": {
+      "type": ["string", "null"],
+      "enum": ["active", "inactive", null]
+    }
+  },
+  "properties": {
+    "required_inline": {
+      "type": ["string", "null"],
+      "enum": ["active", "inactive", null]
+    },
+    "required_ref": {
+      "$ref": "#/definitions/StatusEnum"
+    },
+    "optional_inline": {
+      "type": ["string", "null"],
+      "enum": ["pending", "completed", null]
+    }
+  },
+  "required": ["required_inline", "required_ref"]
+}

tests/main/jsonschema/test_main_jsonschema.py

@@ -4311,6 +4311,27 @@ def test_main_typed_dict_enum_field_as_literal_all(output_file: Path) -> None:
     )
 
 
+@pytest.mark.skipif(
+    black.__version__.split(".")[0] == "22",
+    reason="Installed black doesn't support Python version 3.11",
+)
+def test_main_typed_dict_nullable_enum_literal(output_file: Path) -> None:
+    """Test TypedDict with nullable enum literals generates | None correctly."""
+    run_main_and_assert(
+        input_path=JSON_SCHEMA_DATA_PATH / "nullable_enum_literal_typed_dict.json",
+        output_path=output_file,
+        input_file_type=None,
+        assert_func=assert_file_content,
+        expected_file="typed_dict_nullable_enum_literal.py",
+        extra_args=[
+            "--output-model-type",
+            "typing.TypedDict",
+            "--target-python-version",
+            "3.11",
+        ],
+    )
+
+
 @pytest.mark.cli_doc(
     options=["--use-closed-typed-dict"],
     option_description="""Generate TypedDict with PEP 728 closed/extra_items (default: enabled).