Store current session in Renderer.__call__() (#1329)

Co-authored-by: Barret Schloerke <barret@posit.co>

Author: wch

shiny/render/_data_frame.py

@@ -22,11 +22,7 @@
 from .._docstring import add_example
 from .._typing_extensions import TypedDict
 from .._utils import wrap_async
-from ..session._utils import (
-    get_current_session,
-    require_active_session,
-    session_context,
-)
+from ..session._utils import require_active_session, session_context
 from ._data_frame_utils import (
     AbstractTabularData,
     CellPatch,
@@ -184,13 +180,6 @@ class data_frame(Renderer[DataFrameResult]):
       objects you can return from the rendering function to specify options.
     """
 
-    _session: Session | None  # Do not use. Use `_get_session()` instead
-    """
-    Do not use! Call `._get_session()` instead!
-
-    Internal @render.data_frame session object.
-    """
-
     _value: reactive.Value[DataFrameResult | None]
     """
     Reactive value of the data frame's rendered object.
@@ -758,11 +747,6 @@ def auto_output_ui(self) -> Tag:
         return ui.output_data_frame(id=self.output_id)
 
     def __init__(self, fn: ValueFn[DataFrameResult]):
-        # MUST be done before super().__init__ is called as `_set_output_metadata` is
-        # called in `super().__init__` during auto registration of the output
-        session = get_current_session()
-        self._session = session
-
         super().__init__(fn)
 
         # Set reactives from calculated properties

shiny/render/renderer/_renderer.py

@@ -137,12 +137,6 @@ class Renderer(Generic[IT]):
     asynchonously.
     """
 
-    # Set _session here because some subclasses of Renderer (e.g. data_frame) set
-    # self._session before calling super().__init__(). If we were to set
-    # self._session=None in the __init__ method here, it would overwrite the value from
-    # the subclass. We avoid that by setting it here.
-    _session: Session | None = None
-
     def __call__(self, _fn: ValueFn[IT]) -> Self:
         """
         Add the value function to the renderer.
@@ -163,6 +157,7 @@ def __call__(self, _fn: ValueFn[IT]) -> Self:
         :
             Original renderer instance.
         """
+        from ...session import get_current_session
 
         if not callable(_fn):
             raise TypeError("Value function must be callable")
@@ -179,6 +174,8 @@ def __call__(self, _fn: ValueFn[IT]) -> Self:
         # for auto-registration to occur.
         self.output_id = self.__name__
 
+        self._session = get_current_session()
+
         # Allow for App authors to not require `@output`
         self._auto_register()
 
@@ -220,6 +217,7 @@ def __init__(
         # """
         # Renderer - init docs here
         # """
+        self._session: Session | None = None
         super().__init__()
 
         self._auto_registered: bool = False
@@ -331,16 +329,12 @@ def _auto_register(self) -> None:
         """
         # If in Express mode, register the output
         if not self._auto_registered:
-            from ...session import get_current_session
-
-            s = get_current_session()
-            if s is not None:
+            if self._session is not None:
                 # Register output on reactive graph
-                s.output(self)
+                self._session.output(self)
                 # We mark the fact that we're auto-registered so that, if an explicit
                 # registration now occurs, we can undo this auto-registration.
                 self._auto_registered = True
-                self._session = s
 
 
 # Not inheriting from `WrapAsync[[], IT]` as python 3.8 needs typing extensions that