add global context for session (#2934)

* add global context for session

* export context

Author: 50Bytes-dev

sdk/python/packages/flet-core/src/flet_core/__init__.py

@@ -176,6 +176,7 @@
 from flet_core.outlined_button import OutlinedButton
 from flet_core.padding import Padding
 from flet_core.page import (
+    context,
     AppLifecycleStateChangeEvent,
     KeyboardEvent,
     Locale,

sdk/python/packages/flet-core/src/flet_core/page.py

@@ -1,4 +1,5 @@
 import asyncio
+from contextvars import ContextVar
 import json
 import logging
 import threading
@@ -51,12 +52,20 @@
     ScrollMode,
     ThemeMode,
 )
-from flet_core.utils import deprecated
+from flet_core.utils import deprecated, classproperty
 from flet_core.utils.concurrency_utils import is_pyodide
 from flet_core.view import View
 
 logger = logging.getLogger(flet_core.__name__)
 
+_session_page = ContextVar("flet_session_page", default=None)
+
+
+class context:
+    @classproperty
+    def page(cls) -> "Page":
+        return _session_page.get()
+
 
 try:
     from flet_runtime.auth.authorization import Authorization
@@ -239,6 +248,8 @@ def convert_page_media_change_event(e):
         self.__on_error = EventHandler()
         self._add_event_handler("error", self.__on_error.get_handler())
 
+        _session_page.set(self)
+
     def get_control(self, id):
         return self._index.get(id)
 
@@ -296,6 +307,7 @@ async def fetch_page_details_async(self):
             self._set_attr(props[i], values[i], False)
 
     async def _connect(self, conn: Connection):
+        _session_page.set(self)
         self.__conn = conn
         self.__expires_at = None
         await self.on_event_async(Event("page", "connect", ""))
@@ -495,6 +507,7 @@ def __on_page_change_event(self, data):
                         self._index[id]._set_attr(name, props[name], dirty=False)
 
     def run_task(self, handler: Callable[..., Awaitable[Any]], *args, **kwargs):
+        _session_page.set(self)
         assert asyncio.iscoroutinefunction(handler)
 
         future = asyncio.run_coroutine_threadsafe(handler(*args, **kwargs), self.__loop)
@@ -509,13 +522,24 @@ def _on_completion(f):
 
         return future
 
+    def __context_wrapper(self, handler):
+        def wrapper(*args):
+            _session_page.set(self)
+            handler(*args)
+
+        return wrapper
+
     def run_thread(self, handler, *args):
+        handler_with_context = self.__context_wrapper(handler)
         if is_pyodide():
-            handler(*args)
+            handler_with_context(*args)
         else:
             assert self.__loop
             self.__loop.call_soon_threadsafe(
-                self.__loop.run_in_executor, self.__executor, handler, *args
+                self.__loop.run_in_executor,
+                self.__executor,
+                handler_with_context,
+                *args,
             )
 
     def go(self, route, skip_route_change_event=False, **kwargs):

sdk/python/packages/flet-core/src/flet_core/utils/__init__.py

@@ -3,3 +3,4 @@
 from flet_core.utils.slugify import slugify
 from flet_core.utils.strings import random_string
 from flet_core.utils.vector import Vector
+from flet_core.utils.classproperty import classproperty

sdk/python/packages/flet-core/src/flet_core/utils/classproperty.py

@@ -0,0 +1,12 @@
+from typing import TypeVar, Type, Any, Callable
+
+
+T = TypeVar("T")
+
+
+class classproperty:
+    def __init__(self, func: Callable[[Type[T]], Any]) -> None:
+        self.fget = func
+
+    def __get__(self, instance: T, owner: Type[T]) -> Any:
+        return self.fget(owner)