add typed get_substate variant, improve modify_states typing

reflex/app.py

@@ -26,9 +26,11 @@
     Optional,
     Set,
     Type,
+    TypeVar,
     Union,
     get_args,
     get_type_hints,
+    overload,
 )
 
 from fastapi import FastAPI, HTTPException, Request, UploadFile
@@ -1101,11 +1103,23 @@ async def modify_state(self, token: str) -> AsyncIterator[BaseState]:
                     sid=state.router.session.session_id,
                 )
 
+    S = TypeVar("S", bound=BaseState)
+
+    @overload
+    async def modify_states(
+        self, substate_cls: Type[S], from_state: None
+    ) -> AsyncIterator[S]: ...
+
+    @overload
+    async def modify_states(
+        self, substate_cls: None, from_state: BaseState
+    ) -> AsyncIterator[BaseState]: ...
+
     async def modify_states(
         self,
-        substate_cls: Type[BaseState] | None = None,
+        substate_cls: Type[S] | Type[BaseState] | None = None,
         from_state: BaseState | None = None,
-    ) -> AsyncIterator[BaseState]:
+    ) -> AsyncIterator[S] | AsyncIterator[BaseState]:
         """Iterate over the states.
 
         Args:
@@ -1128,11 +1142,11 @@ async def modify_states(
                 from_state is not None
                 and from_state.router.session.client_token == token
             ):
-                yield from_state
+                state = from_state
                 continue
             async with self.modify_state(token) as state:
                 if substate_cls is not None:
-                    state = state.get_substate(substate_cls.get_name())
+                    state = state.get_substate(substate_cls)
                 yield state
 
     def _process_background(

reflex/state.py

@@ -24,8 +24,10 @@
     Sequence,
     Set,
     Type,
+    TypeVar,
     Union,
     cast,
+    overload,
 )
 
 import dill
@@ -291,6 +293,9 @@ def __call__(self, *args: Any) -> EventSpec:
         return super().__call__(*args)
 
 
+S = TypeVar("S", bound="BaseState")
+
+
 class BaseState(Base, ABC, extra=pydantic.Extra.allow):
     """The state of the app."""
 
@@ -1151,18 +1156,28 @@ def _reset_client_storage(self):
         for substate in self.substates.values():
             substate._reset_client_storage()
 
-    def get_substate(self, path: Sequence[str]) -> BaseState:
+    @overload
+    def get_substate(self, path: Sequence[str]) -> BaseState: ...
+
+    @overload
+    def get_substate(self, path: Type[S]) -> S: ...
+
+    def get_substate(self, path: Sequence[str] | Type[S]) -> BaseState | S:
         """Get the substate.
 
         Args:
-            path: The path to the substate.
+            path: The path to the substate or the class of the substate.
 
         Returns:
             The substate.
 
         Raises:
             ValueError: If the substate is not found.
         """
+        if isinstance(path, type):
+            path = (
+                path.get_full_name().removeprefix(f"{self.get_full_name()}.").split(".")
+            )
         if len(path) == 0:
             return self
         if path[0] == self.get_name():
@@ -1295,7 +1310,7 @@ def _get_state_from_cache(self, state_cls: Type[BaseState]) -> BaseState:
             root_state = self
         else:
             root_state = self._get_parent_states()[-1][1]
-        return root_state.get_substate(state_cls.get_full_name().split("."))
+        return root_state.get_substate(state_cls)
 
     async def _get_state_from_redis(self, state_cls: Type[BaseState]) -> BaseState:
         """Get a state instance from redis.

reflex/utils/prerequisites.py

@@ -287,9 +287,6 @@ def get_app(reload: bool = False) -> App:
 
     Returns:
         The app based on the default config.
-
-    Raises:
-        RuntimeError: If the app name is not set in the config.
     """
     return getattr(get_app_module(reload=reload), constants.CompileVars.APP)
 

tests/test_state.py

@@ -218,7 +218,7 @@ def child_state(test_state) -> ChildState:
     Returns:
         A test child state.
     """
-    child_state = test_state.get_substate([ChildState.get_name()])
+    child_state = test_state.get_substate(ChildState)
     assert child_state is not None
     return child_state
 
@@ -233,7 +233,7 @@ def child_state2(test_state) -> ChildState2:
     Returns:
         A second test child state.
     """
-    child_state2 = test_state.get_substate([ChildState2.get_name()])
+    child_state2 = test_state.get_substate(ChildState2)
     assert child_state2 is not None
     return child_state2
 
@@ -248,7 +248,7 @@ def grandchild_state(child_state) -> GrandchildState:
     Returns:
         A test state.
     """
-    grandchild_state = child_state.get_substate([GrandchildState.get_name()])
+    grandchild_state = child_state.get_substate(GrandchildState)
     assert grandchild_state is not None
     return grandchild_state
 
@@ -1183,7 +1183,7 @@ def set_v4(self, v: int):
     assert ms.v == 2
 
     # ensure handler can be called from substate (referencing grandparent handler)
-    ms.get_substate(tuple(SubSubState.get_full_name().split("."))).set_v4(3)
+    ms.get_substate(SubSubState).set_v4(3)
     assert ms.v == 3
 
 
@@ -2854,7 +2854,7 @@ async def test_get_state(mock_app: rx.App, token: str):
     )
 
     # Get the child_state2 directly.
-    child_state2_direct = test_state.get_substate([ChildState2.get_name()])
+    child_state2_direct = test_state.get_substate(ChildState2)
     child_state2_get_state = await test_state.get_state(ChildState2)
     # These should be the same object.
     assert child_state2_direct is child_state2_get_state
@@ -2871,15 +2871,13 @@ async def test_get_state(mock_app: rx.App, token: str):
     )
 
     # ChildState should be retrievable
-    child_state_direct = test_state.get_substate([ChildState.get_name()])
+    child_state_direct = test_state.get_substate(ChildState)
     child_state_get_state = await test_state.get_state(ChildState)
     # These should be the same object.
     assert child_state_direct is child_state_get_state
 
     # GrandchildState instance should be the same as the one retrieved from the child_state2.
-    assert grandchild_state is child_state_direct.get_substate(
-        [GrandchildState.get_name()]
-    )
+    assert grandchild_state is child_state_direct.get_substate(GrandchildState)
     grandchild_state.value2 = "set_value"
 
     assert test_state.get_delta() == {
@@ -2920,7 +2918,7 @@ async def test_get_state(mock_app: rx.App, token: str):
         )
 
     # Set a value on child_state2, should update cached var in grandchild_state2
-    child_state2 = new_test_state.get_substate((ChildState2.get_name(),))
+    child_state2 = new_test_state.get_substate(ChildState2)
     child_state2.value = "set_c2_value"
 
     assert new_test_state.get_delta() == {
@@ -3015,7 +3013,7 @@ class GreatGrandchild3(Grandchild3):
         assert Child3.get_name() in root.substates  # (due to @rx.var)
 
     # Get the unconnected sibling state, which will be used to `get_state` other instances.
-    child = root.get_substate(Child.get_full_name().split("."))
+    child = root.get_substate(Child)
 
     # Get an uncached child state.
     child2 = await child.get_state(Child2)