fix(OpenAPI): Correctly handle type keyword (#3715)

* support type keyword

* make pyright happy

* fix tests

* fix coverage upload

.github/workflows/ci.yml

@@ -320,6 +320,7 @@ jobs:
         with:
           name: coverage-data
           path: .coverage.pydantic_v1
+          include-hidden-files: true
 
   upload-test-coverage:
     runs-on: ubuntu-latest

.github/workflows/test.yml

@@ -67,3 +67,4 @@ jobs:
         with:
           name: coverage-data
           path: .coverage.${{ inputs.python-version }}
+          include-hidden-files: true

litestar/_openapi/schema_generation/schema.py

@@ -328,6 +328,8 @@ def for_field_definition(self, field_definition: FieldDefinition) -> Schema | Re
 
         if field_definition.is_new_type:
             result = self.for_new_type(field_definition)
+        elif field_definition.is_type_alias_type:
+            result = self.for_type_alias_type(field_definition)
         elif plugin_for_annotation := self.get_plugin_for(field_definition):
             result = self.for_plugin(field_definition, plugin_for_annotation)
         elif _should_create_enum_schema(field_definition):
@@ -366,6 +368,16 @@ def for_new_type(self, field_definition: FieldDefinition) -> Schema | Reference:
             )
         )
 
+    def for_type_alias_type(self, field_definition: FieldDefinition) -> Schema | Reference:
+        return self.for_field_definition(
+            FieldDefinition.from_kwarg(
+                annotation=field_definition.annotation.__value__,
+                name=field_definition.name,
+                default=field_definition.default,
+                kwarg_definition=field_definition.kwarg_definition,
+            )
+        )
+
     @staticmethod
     def for_upload_file(field_definition: FieldDefinition) -> Schema:
         """Create schema for UploadFile.

litestar/typing.py

@@ -8,7 +8,17 @@
 from typing import Any, AnyStr, Callable, Collection, ForwardRef, Literal, Mapping, Protocol, Sequence, TypeVar, cast
 
 from msgspec import UnsetType
-from typing_extensions import NewType, NotRequired, Required, Self, get_args, get_origin, get_type_hints, is_typeddict
+from typing_extensions import (
+    NewType,
+    NotRequired,
+    Required,
+    Self,
+    TypeAliasType,
+    get_args,
+    get_origin,
+    get_type_hints,
+    is_typeddict,
+)
 
 from litestar.exceptions import ImproperlyConfiguredException, LitestarWarning
 from litestar.openapi.spec import Example
@@ -363,6 +373,11 @@ def is_tuple(self) -> bool:
     def is_new_type(self) -> bool:
         return isinstance(self.annotation, NewType)
 
+    @property
+    def is_type_alias_type(self) -> bool:
+        """Whether the annotation is a ``TypeAliasType``"""
+        return isinstance(self.annotation, TypeAliasType)
+
     @property
     def is_type_var(self) -> bool:
         """Whether the annotation is a TypeVar or not."""

tests/unit/test_openapi/test_schema.py

@@ -21,7 +21,7 @@
 import msgspec
 import pytest
 from msgspec import Struct
-from typing_extensions import Annotated, TypeAlias
+from typing_extensions import Annotated, TypeAlias, TypeAliasType
 
 from litestar import Controller, MediaType, get, post
 from litestar._openapi.schema_generation.plugins import openapi_schema_plugins
@@ -615,3 +615,32 @@ async def handler(dep: str) -> None:
         assert param.name == f"param{i}"
         assert param.required is True
         assert param.param_in is ParamType.PATH
+
+
+def test_type_alias_type() -> None:
+    @get("/")
+    def handler(query_param: Annotated[TypeAliasType("IntAlias", int), Parameter(description="foo")]) -> None:  # type: ignore[valid-type]
+        pass
+
+    app = Litestar([handler])
+    param = app.openapi_schema.paths["/"].get.parameters[0]  # type: ignore[index, union-attr]
+    assert param.schema.type is OpenAPIType.INTEGER  # type: ignore[union-attr]
+    # ensure other attributes than the plain type are carried over correctly
+    assert param.description == "foo"
+
+
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="type keyword not available before 3.12")
+def test_type_alias_type_keyword() -> None:
+    ctx: Dict[str, Any] = {}
+    exec("type IntAlias = int", ctx, None)
+    annotation = ctx["IntAlias"]
+
+    @get("/")
+    def handler(query_param: Annotated[annotation, Parameter(description="foo")]) -> None:  # type: ignore[valid-type]
+        pass
+
+    app = Litestar([handler])
+    param = app.openapi_schema.paths["/"].get.parameters[0]  # type: ignore[union-attr, index]
+    assert param.schema.type is OpenAPIType.INTEGER  # type: ignore[union-attr]
+    # ensure other attributes than the plain type are carried over correctly
+    assert param.description == "foo"

tests/unit/test_typing.py

@@ -7,7 +7,7 @@
 import annotated_types
 import msgspec
 import pytest
-from typing_extensions import Annotated, NotRequired, Required, TypedDict, get_type_hints
+from typing_extensions import Annotated, NotRequired, Required, TypeAliasType, TypedDict, get_type_hints
 
 from litestar import get
 from litestar.exceptions import LitestarWarning
@@ -476,3 +476,17 @@ def handler(foo: Annotated[int, Parameter(default=1)]) -> None:
     (record,) = warnings
     assert record.category == DeprecationWarning
     assert "Deprecated default value specification" in str(record.message)
+
+
+def test_is_type_alias_type() -> None:
+    field_definition = FieldDefinition.from_annotation(TypeAliasType("IntAlias", int))  # pyright: ignore
+    assert field_definition.is_type_alias_type
+
+
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="type keyword not available before 3.12")
+def test_unwrap_type_alias_type_keyword() -> None:
+    ctx: dict[str, Any] = {}
+    exec("type IntAlias = int", ctx, None)
+    annotation = ctx["IntAlias"]
+    field_definition = FieldDefinition.from_annotation(annotation)
+    assert field_definition.is_type_alias_type