Add middleware type alias (#5898)

CHANGES/5898.feature

@@ -0,0 +1 @@
+Add a middleware type alias ``aiohttp.typedefs.Middleware``.

aiohttp/typedefs.py

@@ -49,5 +49,6 @@
 ]
 
 Handler = Callable[["Request"], Awaitable["StreamResponse"]]
+Middleware = Callable[["Request", Handler], Awaitable["StreamResponse"]]
 
 PathLike = Union[str, "os.PathLike[str]"]

aiohttp/web_app.py

@@ -28,6 +28,7 @@
 
 from . import hdrs
 from .log import web_logger
+from .typedefs import Middleware
 from .web_middlewares import _fix_request_current_app
 from .web_request import Request
 from .web_response import StreamResponse
@@ -46,20 +47,16 @@
 
 
 if TYPE_CHECKING:  # pragma: no cover
-    from .typedefs import Handler
-
     _AppSignal = Signal[Callable[["Application"], Awaitable[None]]]
     _RespPrepareSignal = Signal[Callable[[Request, StreamResponse], Awaitable[None]]]
-    _Middleware = Callable[[Request, Handler], Awaitable[StreamResponse]]
-    _Middlewares = FrozenList[_Middleware]
-    _MiddlewaresHandlers = Sequence[_Middleware]
+    _Middlewares = FrozenList[Middleware]
+    _MiddlewaresHandlers = Sequence[Middleware]
     _Subapps = List["Application"]
 else:
     # No type checker mode, skip types
     _AppSignal = Signal
     _RespPrepareSignal = Signal
     _Handler = Callable
-    _Middleware = Callable
     _Middlewares = FrozenList
     _MiddlewaresHandlers = Sequence
     _Subapps = List
@@ -92,7 +89,7 @@ def __init__(
         self,
         *,
         logger: logging.Logger = web_logger,
-        middlewares: Iterable[_Middleware] = (),
+        middlewares: Iterable[Middleware] = (),
         handler_args: Optional[Mapping[str, Any]] = None,
         client_max_size: int = 1024 ** 2,
         debug: Any = ...,  # mypy doesn't support ellipsis
@@ -325,7 +322,7 @@ async def cleanup(self) -> None:
             # If an exception occurs in startup, ensure cleanup contexts are completed.
             await self._cleanup_ctx._on_cleanup(self)
 
-    def _prepare_middleware(self) -> Iterator[_Middleware]:
+    def _prepare_middleware(self) -> Iterator[Middleware]:
         yield from reversed(self._middlewares)
         yield _fix_request_current_app(self)
 

aiohttp/web_middlewares.py

@@ -1,8 +1,8 @@
 import re
 import warnings
-from typing import TYPE_CHECKING, Awaitable, Callable, Tuple, Type, TypeVar
+from typing import TYPE_CHECKING, Tuple, Type, TypeVar
 
-from .typedefs import Handler
+from .typedefs import Handler, Middleware
 from .web_exceptions import HTTPMove, HTTPPermanentRedirect
 from .web_request import Request
 from .web_response import StreamResponse
@@ -42,16 +42,13 @@ def middleware(f: _Func) -> _Func:
     return f
 
 
-_Middleware = Callable[[Request, Handler], Awaitable[StreamResponse]]
-
-
 def normalize_path_middleware(
     *,
     append_slash: bool = True,
     remove_slash: bool = False,
     merge_slashes: bool = True,
     redirect_class: Type[HTTPMove] = HTTPPermanentRedirect,
-) -> _Middleware:
+) -> Middleware:
     """
     Middleware factory which produces a middleware that normalizes
     the path of a request. By normalizing it means:
@@ -118,7 +115,7 @@ async def impl(request: Request, handler: Handler) -> StreamResponse:
     return impl
 
 
-def _fix_request_current_app(app: "Application") -> _Middleware:
+def _fix_request_current_app(app: "Application") -> Middleware:
     async def impl(request: Request, handler: Handler) -> StreamResponse:
         with request.match_info.set_current_app(app):
             return await handler(request)