feat(typing): support typing.ReadOnly for TypedDict schemas (#4424)

Author: sobolevn

docs/release-notes/changelog.rst

@@ -261,3 +261,19 @@
             difference is expected. Some test cases may break though if they relied on
             the fact that the middleware wrapper created by ``ASGIMiddleware`` was
             always being called
+
+    .. change:: Support for ``typing.ReadOnly`` in typed dict schemas
+        :type: feature
+        :issue: 4423
+        :pr: 4424
+
+        Support unwrapping ``ReadOnly`` type in schemas like:
+
+        .. code:: python
+
+          from typing import ReadOnly, TypedDict
+
+          class User(TypedDict):
+              id: ReadOnly[int]
+
+        ``typing_extensions.ReadOnly`` should be used for python versions <3.13.

litestar/utils/typing.py

@@ -36,7 +36,16 @@
     cast,
 )
 
-from typing_extensions import Annotated, NewType, NotRequired, Required, get_args, get_origin, get_type_hints
+from typing_extensions import (
+    Annotated,
+    NewType,
+    NotRequired,
+    ReadOnly,
+    Required,
+    get_args,
+    get_origin,
+    get_type_hints,
+)
 
 from litestar.types.builtin_types import NoneType, UnionTypes
 
@@ -122,7 +131,7 @@
 different args, and types.
 """
 
-wrapper_type_set = {Annotated, Required, NotRequired}
+wrapper_type_set = {Annotated, Required, NotRequired, ReadOnly}
 """Types that always contain a wrapped type annotation as their first arg."""
 
 
@@ -145,7 +154,9 @@ def make_non_optional_union(annotation: UnionT | None) -> UnionT:
 
 
 def unwrap_annotation(annotation: Any) -> tuple[Any, tuple[Any, ...], set[Any]]:
-    """Remove "wrapper" annotation types, such as ``Annotated``, ``Required``, and ``NotRequired``.
+    """Remove "wrapper" annotation types.
+
+    Such as ``Annotated``, ``ReadOnly``, ``Required``, and ``NotRequired``.
 
     Note:
         ``annotation`` should have been retrieved from :func:`get_type_hints()` with ``include_extras=True``. This

tests/models.py

@@ -5,7 +5,7 @@
 
 import msgspec
 from polyfactory.factories import DataclassFactory
-from typing_extensions import NotRequired, Required, TypedDict
+from typing_extensions import NotRequired, ReadOnly, Required, TypedDict
 
 
 class Species(str, Enum):
@@ -35,7 +35,7 @@ class DataclassPerson:
 class TypedDictPerson(TypedDict):
     first_name: Required[str]
     last_name: Required[str]
-    id: Required[str]
+    id: Required[ReadOnly[str]]
     optional: NotRequired[Optional[str]]
     complex: Required[dict[str, list[dict[str, str]]]]
     pets: NotRequired[Optional[list[DataclassPet]]]

tests/unit/test_openapi/test_request_body.py

@@ -1,8 +1,9 @@
 from dataclasses import dataclass
-from typing import Annotated, Any, Callable
+from typing import Annotated, Any, Callable, TypedDict
 from unittest.mock import ANY, MagicMock
 
 import pytest
+from typing_extensions import ReadOnly
 
 from litestar import Controller, Litestar, get, post
 from litestar._openapi.datastructures import OpenAPIContext
@@ -181,3 +182,38 @@ async def handler(data: dict[str, Any]) -> None:
     mock_dto.create_openapi_schema.assert_called_once_with(
         field_definition=field_definition, handler_id=resolved_handler.handler_id, schema_creator=ANY
     )
+
+
+def test_unwrap_read_only() -> None:
+    class SchemaDict(TypedDict):
+        id: ReadOnly[int]
+        email: str
+
+    @post("/")
+    async def handler(
+        data: SchemaDict,
+    ) -> SchemaDict:
+        return {"id": data["id"], "email": "[email protected]"}
+
+    app = Litestar([handler])
+    schema = app.openapi_schema.to_schema()
+
+    assert schema["paths"]["/"]["post"]["requestBody"]["content"]["application/json"] == {
+        "schema": {"$ref": "#/components/schemas/test_unwrap_read_only.SchemaDict"}
+    }
+    assert schema["paths"]["/"]["post"]["responses"]["201"]["content"]["application/json"] == {
+        "schema": {"$ref": "#/components/schemas/test_unwrap_read_only.SchemaDict"}
+    }
+    assert schema["components"] == {
+        "schemas": {
+            "test_unwrap_read_only.SchemaDict": {
+                "properties": {
+                    "id": {"type": "integer"},
+                    "email": {"type": "string"},
+                },
+                "type": "object",
+                "required": ["email", "id"],
+                "title": "SchemaDict",
+            }
+        }
+    }