Add TypedDict support for middleware context data

Introduced `MiddlewareData` and associated TypedDicts to type-hint middleware context data. Updated documentation to include usage examples and guidelines for extending the default middleware data. Also adjusted coverage configuration to exclude the new data module.

CHANGES/1637.feature.rst

@@ -0,0 +1,4 @@
+Add TypedDict definitions for middleware context data to the dispatcher dependency injection docs.
+
+So, now you can use :class:`aiogram.dispatcher.middleware.data.MiddlewareData` directly or
+extend it with your own data in the middlewares.

aiogram/dispatcher/middlewares/data.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, TypedDict
+
+from typing_extensions import NotRequired
+
+if TYPE_CHECKING:
+    from aiogram import Bot, Dispatcher, Router
+    from aiogram.dispatcher.event.handler import HandlerObject
+    from aiogram.dispatcher.middlewares.user_context import EventContext
+    from aiogram.fsm.context import FSMContext
+    from aiogram.fsm.storage.base import BaseStorage
+    from aiogram.types import Chat, Update, User
+    from aiogram.utils.i18n import I18n, I18nMiddleware
+
+
+class DispatcherData(TypedDict, total=False):
+    """
+    Dispatcher and bot related data.
+    """
+
+    dispatcher: Dispatcher
+    bot: Bot
+    bots: list[Bot]
+    event_update: Update
+    event_router: Router
+    handler: NotRequired[HandlerObject]
+
+
+class UserContextData(TypedDict, total=False):
+    """
+    Event context related data about user and chat.
+    """
+
+    event_context: EventContext
+    event_from_user: NotRequired[User]
+    event_chat: NotRequired[Chat]  # Deprecated
+    event_thread_id: NotRequired[int]  # Deprecated
+    event_business_connection_id: NotRequired[str]  # Deprecated
+
+
+class FSMData(TypedDict, total=False):
+    """
+    FSM related data.
+    """
+
+    fsm_storage: BaseStorage
+    state: NotRequired[FSMContext]
+    raw_state: NotRequired[str | None]
+
+
+class I18nData(TypedDict, total=False):
+    """
+    I18n related data.
+
+    Is not included by default, you need to add it to your own Data class if you need it.
+    """
+
+    i18n: I18n
+    i18n_middleware: I18nMiddleware
+
+
+class MiddlewareData(
+    DispatcherData,
+    UserContextData,
+    FSMData,
+    # I18nData, # Disabled by default, add it if you need it to your own Data class.
+    total=False,
+):
+    """
+    Data passed to the handler by the middlewares.
+
+    You can add your own data by extending this class.
+    """

docs/dispatcher/dependency_injection.rst

@@ -70,3 +70,61 @@ The last way is to return a dictionary from the filter:
 .. literalinclude:: ../../examples/context_addition_from_filter.py
 
 ...or using :ref:`MagicFilter <magic-filters>` with :code:`.as_(...)` method.
+
+
+Using type hints
+================
+
+.. note::
+
+    Type-hinting middleware data is optional and is not required for the correct operation of the dispatcher.
+    However, it is recommended to use it to improve the readability of the code.
+
+You can use type hints to specify the type of the context data in the middlewares, filters and handlers.
+
+The default middleware data typed dict can be found in :class:`aiogram.dispatcher.middlewares.data.MiddlewareData`.
+
+In case when you have extended the context data, you can use the :class:`aiogram.dispatcher.middlewares.data.MiddlewareData` as a base class and specify the type hints for the new fields.
+
+.. warning::
+
+    If you using type checking tools like mypy, you can experience warnings about that this type hint against Liskov substitution principle in due stricter type is not a subclass of :code:`dict[str, Any]`.
+    This is a known issue and it is not a bug. You can ignore this warning or use :code:`# type: ignore` comment.
+
+Example of using type hints:
+
+.. code-block:: python
+
+    from aiogram.dispatcher.middlewares.data import MiddlewareData
+
+
+    class MyMiddlewareData(MiddlewareData, total=False):
+        my_custom_value: int
+
+
+    class MyMessageMiddleware(BaseMiddleware):
+        async def __call__(
+            self,
+            handler: Callable[[Message, MiddlewareData], Awaitable[Any]],
+            event: Message,
+            data: MiddlewareData,
+        ) -> Any:
+            bot = data["bot"]  # <-- IDE will show you that data has `bot` key and its type is `Bot`
+
+            data["my_custom_value"] = 42  # <-- IDE will show you that you can set `my_custom_value` key with int value and warn you if you try to set it with other type
+            return await handler(event, data))
+
+
+Available context data type helpers
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. autoclass:: aiogram.dispatcher.middlewares.data.MiddlewareData
+    :members:
+    :undoc-members:
+    :member-order: bysource
+
+
+.. autoclass:: aiogram.dispatcher.middlewares.data.I18nData
+    :members:
+    :undoc-members:
+    :member-order: bysource

pyproject.toml

@@ -261,7 +261,8 @@ filterwarnings = [
 branch = false
 parallel = true
 omit = [
-    "aiogram/__about__.py",
+    "aiogram/__meta__.py",
+    "aiogram/dispatcher/middlewares/data.py"
 ]
 
 [tool.coverage.report]