From ecb9f141e4029903e95de284fef92b180844fe0a Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 26 Sep 2024 08:38:21 +0000
Subject: [PATCH 01/12] Setting State Vars that are not defined should raise an
 error

---
 reflex/state.py           |  3 +++
 tests/units/test_state.py | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/reflex/state.py b/reflex/state.py
index cda36a0a91..d7cfcf18bc 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1277,6 +1277,9 @@ def __setattr__(self, name: str, value: Any):
             self._mark_dirty()
             return
 
+        if not name in self.vars and not name in self._computed_var_dependencies and not name in self.get_skip_vars():
+            raise AttributeError(f"The state var '{name}' has not been defined in '{type(self).__name__}'. All state vars must be declared before they can be set.")
+
         # Set the attribute.
         super().__setattr__(name, value)
 
diff --git a/tests/units/test_state.py b/tests/units/test_state.py
index 205162b9f2..b85116101d 100644
--- a/tests/units/test_state.py
+++ b/tests/units/test_state.py
@@ -3262,3 +3262,26 @@ def test_child_mixin_state() -> None:
 
     assert "computed" in ChildUsesMixinState.inherited_vars
     assert "computed" not in ChildUsesMixinState.computed_vars
+
+
+def test_assignment_to_undeclared_vars():
+    """Test that an attribute error is thrown when undeclared vars are set"""
+    class State(BaseState):
+        val: str
+
+        def handle(self):
+            self.num = 5
+
+    class Substate(State):
+
+        def handle_var(self):
+            self.value = 20
+
+    state = State()
+    sub_state = Substate()
+
+    with pytest.raises(AttributeError):
+        state.handle()
+
+    with pytest.raises(AttributeError):
+        sub_state.handle()

From b34a5d3b5455ec642f0a875145b9ecaaebb27001 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 26 Sep 2024 11:44:56 +0000
Subject: [PATCH 02/12] `self.var` contains all the info we need

---
 reflex/state.py           | 6 ++++--
 tests/units/test_state.py | 7 +++++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/reflex/state.py b/reflex/state.py
index d7cfcf18bc..ab22fd6886 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1277,8 +1277,10 @@ def __setattr__(self, name: str, value: Any):
             self._mark_dirty()
             return
 
-        if not name in self.vars and not name in self._computed_var_dependencies and not name in self.get_skip_vars():
-            raise AttributeError(f"The state var '{name}' has not been defined in '{type(self).__name__}'. All state vars must be declared before they can be set.")
+        if name not in self.vars and name not in self.get_skip_vars():
+            raise AttributeError(
+                f"The state var '{name}' has not been defined in '{type(self).__name__}'. All state vars must be declared before they can be set."
+            )
 
         # Set the attribute.
         super().__setattr__(name, value)
diff --git a/tests/units/test_state.py b/tests/units/test_state.py
index b85116101d..d4ece2b812 100644
--- a/tests/units/test_state.py
+++ b/tests/units/test_state.py
@@ -3265,7 +3265,8 @@ def test_child_mixin_state() -> None:
 
 
 def test_assignment_to_undeclared_vars():
-    """Test that an attribute error is thrown when undeclared vars are set"""
+    """Test that an attribute error is thrown when undeclared vars are set."""
+
     class State(BaseState):
         val: str
 
@@ -3273,7 +3274,6 @@ def handle(self):
             self.num = 5
 
     class Substate(State):
-
         def handle_var(self):
             self.value = 20
 
@@ -3285,3 +3285,6 @@ def handle_var(self):
 
     with pytest.raises(AttributeError):
         sub_state.handle()
+
+    with pytest.raises(AttributeError):
+        sub_state.handle_var()

From 07a0560145a4438903cd9aa5c434b60ae1833a35 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 26 Sep 2024 12:01:00 +0000
Subject: [PATCH 03/12] tests fix

---
 reflex/state.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/reflex/state.py b/reflex/state.py
index ab22fd6886..22d79120e8 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1277,9 +1277,15 @@ def __setattr__(self, name: str, value: Any):
             self._mark_dirty()
             return
 
-        if name not in self.vars and name not in self.get_skip_vars():
+        if (
+            not name.startswith("__")
+            and name not in self.vars
+            and name not in self.get_skip_vars()
+        ):
+            available_vars = ", ".join(self.vars) or "None"
             raise AttributeError(
-                f"The state var '{name}' has not been defined in '{type(self).__name__}'. All state vars must be declared before they can be set."
+                f"The state variable '{name}' has not been defined in '{type(self).__name__}'. "
+                f"All state variables must be declared before they can be set. Available vars: {available_vars}"
             )
 
         # Set the attribute.

From c3a2688948303e43ac6d6f9b3e67687654090078 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 26 Sep 2024 15:04:25 +0000
Subject: [PATCH 04/12] tests fix

---
 reflex/state.py           | 3 +--
 tests/units/test_state.py | 7 ++-----
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/reflex/state.py b/reflex/state.py
index 22d79120e8..515370be08 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1282,10 +1282,9 @@ def __setattr__(self, name: str, value: Any):
             and name not in self.vars
             and name not in self.get_skip_vars()
         ):
-            available_vars = ", ".join(self.vars) or "None"
             raise AttributeError(
                 f"The state variable '{name}' has not been defined in '{type(self).__name__}'. "
-                f"All state variables must be declared before they can be set. Available vars: {available_vars}"
+                f"All state variables must be declared before they can be set."
             )
 
         # Set the attribute.
diff --git a/tests/units/test_state.py b/tests/units/test_state.py
index d4ece2b812..1f5c6a70c2 100644
--- a/tests/units/test_state.py
+++ b/tests/units/test_state.py
@@ -3277,14 +3277,11 @@ class Substate(State):
         def handle_var(self):
             self.value = 20
 
-    state = State()
-    sub_state = Substate()
+    state = State()  # type: ignore
+    sub_state = Substate()  # type: ignore
 
     with pytest.raises(AttributeError):
         state.handle()
 
-    with pytest.raises(AttributeError):
-        sub_state.handle()
-
     with pytest.raises(AttributeError):
         sub_state.handle_var()

From dbf43b1b09cf939ab7d0e376e486762b3f44a1e5 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 26 Sep 2024 15:17:37 +0000
Subject: [PATCH 05/12] precommit fix

---
 reflex/state.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/reflex/state.py b/reflex/state.py
index 515370be08..cfe8201414 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1260,6 +1260,9 @@ def __setattr__(self, name: str, value: Any):
         Args:
             name: The name of the attribute.
             value: The value of the attribute.
+
+        Raises:
+            AttributeError: If a value of a var is set without first defining it.
         """
         if isinstance(value, MutableProxy):
             # unwrap proxy objects when assigning back to the state

From 15af1cade4117a8bb590b2ecade626aca74bd226 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 26 Sep 2024 17:28:37 +0000
Subject: [PATCH 06/12] restrict this only to frontend vars for now.

---
 reflex/state.py           |  4 +++-
 tests/units/test_state.py | 26 ++++++++++++++++++++++++--
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/reflex/state.py b/reflex/state.py
index cfe8201414..95a767feab 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1281,7 +1281,9 @@ def __setattr__(self, name: str, value: Any):
             return
 
         if (
-            not name.startswith("__")
+            not name.startswith(
+                "_"
+            )  # TODO: skipping backend vars and vars with double leading underscores for now. They should be supported, however.
             and name not in self.vars
             and name not in self.get_skip_vars()
         ):
diff --git a/tests/units/test_state.py b/tests/units/test_state.py
index 1f5c6a70c2..06362f4435 100644
--- a/tests/units/test_state.py
+++ b/tests/units/test_state.py
@@ -3269,10 +3269,23 @@ def test_assignment_to_undeclared_vars():
 
     class State(BaseState):
         val: str
+        _val: str
+        __val: str
 
-        def handle(self):
+        def handle_supported_regular_vars(self):
+            self.val = "no underscore"
+            self._val = "single leading underscore"
+            self.__val = "double leading undercore"
+
+        def handle_regular_var(self):
             self.num = 5
 
+        def handle_backend_var(self):
+            self._num = 5
+
+        def handle_non_var(self):
+            self.__num = 5
+
     class Substate(State):
         def handle_var(self):
             self.value = 20
@@ -3281,7 +3294,16 @@ def handle_var(self):
     sub_state = Substate()  # type: ignore
 
     with pytest.raises(AttributeError):
-        state.handle()
+        state.handle_regular_var()
 
     with pytest.raises(AttributeError):
         sub_state.handle_var()
+
+    # TODO: uncomment this if the case of backend vars are supported.
+    # with pytest.raises(AttributeError):
+    #     state.handle_backend_var()
+    #
+    # with pytest.raises(AttributeError):
+    #     state.handle_non_var()
+
+    state.handle_supported_regular_vars()

From 28f210c5193eaf7f067ec5b59d4de5128dfc63f6 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 26 Sep 2024 17:32:01 +0000
Subject: [PATCH 07/12] pyright fix

---
 tests/units/test_state.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/units/test_state.py b/tests/units/test_state.py
index 06362f4435..d3612231c5 100644
--- a/tests/units/test_state.py
+++ b/tests/units/test_state.py
@@ -3270,7 +3270,7 @@ def test_assignment_to_undeclared_vars():
     class State(BaseState):
         val: str
         _val: str
-        __val: str
+        __val: str  # type: ignore
 
         def handle_supported_regular_vars(self):
             self.val = "no underscore"

From cd91136de67bc62faf56a99f17ff60f3ef9be1e2 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Wed, 2 Oct 2024 17:27:41 +0000
Subject: [PATCH 08/12] use custom exception

---
 reflex/state.py            | 5 +++--
 reflex/utils/exceptions.py | 4 ++++
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/reflex/state.py b/reflex/state.py
index 95a767feab..5e97832730 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -74,6 +74,7 @@
     EventHandlerShadowsBuiltInStateMethod,
     ImmutableStateError,
     LockExpiredError,
+    SetUndefinedStateVarError,
 )
 from reflex.utils.exec import is_testing_env
 from reflex.utils.serializers import serializer
@@ -1262,7 +1263,7 @@ def __setattr__(self, name: str, value: Any):
             value: The value of the attribute.
 
         Raises:
-            AttributeError: If a value of a var is set without first defining it.
+            SetUndefinedStateVar: If a value of a var is set without first defining it.
         """
         if isinstance(value, MutableProxy):
             # unwrap proxy objects when assigning back to the state
@@ -1287,7 +1288,7 @@ def __setattr__(self, name: str, value: Any):
             and name not in self.vars
             and name not in self.get_skip_vars()
         ):
-            raise AttributeError(
+            raise SetUndefinedStateVarError(
                 f"The state variable '{name}' has not been defined in '{type(self).__name__}'. "
                 f"All state variables must be declared before they can be set."
             )
diff --git a/reflex/utils/exceptions.py b/reflex/utils/exceptions.py
index 7c35328612..9c79a387ae 100644
--- a/reflex/utils/exceptions.py
+++ b/reflex/utils/exceptions.py
@@ -115,3 +115,7 @@ class PrimitiveUnserializableToJSON(ReflexError, ValueError):
 
 class InvalidLifespanTaskType(ReflexError, TypeError):
     """Raised when an invalid task type is registered as a lifespan task."""
+
+
+class SetUndefinedStateVarError(ReflexError, AttributeError):
+    """Raised when setting the value of a var without first declaring it."""

From bb8d7c5d15a57a328289f11abe506728f43feec5 Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Wed, 2 Oct 2024 22:20:52 +0000
Subject: [PATCH 09/12] fix darglint

---
 reflex/state.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/reflex/state.py b/reflex/state.py
index 5e97832730..041fa04aeb 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1263,7 +1263,7 @@ def __setattr__(self, name: str, value: Any):
             value: The value of the attribute.
 
         Raises:
-            SetUndefinedStateVar: If a value of a var is set without first defining it.
+            SetUndefinedStateVarError: If a value of a var is set without first defining it.
         """
         if isinstance(value, MutableProxy):
             # unwrap proxy objects when assigning back to the state

From c51d6752c67f42bd8bc5152e0556b6fccb09d58f Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 3 Oct 2024 08:35:00 +0000
Subject: [PATCH 10/12] backend vars logic is now supported

---
 reflex/state.py           |  5 ++---
 tests/units/test_state.py | 14 ++++++--------
 2 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/reflex/state.py b/reflex/state.py
index 041fa04aeb..bd3cc79eaa 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1282,9 +1282,8 @@ def __setattr__(self, name: str, value: Any):
             return
 
         if (
-            not name.startswith(
-                "_"
-            )  # TODO: skipping backend vars and vars with double leading underscores for now. They should be supported, however.
+            not name.startswith("__")
+            and not name.startswith(f"_{type(self).__name__}__")
             and name not in self.vars
             and name not in self.get_skip_vars()
         ):
diff --git a/tests/units/test_state.py b/tests/units/test_state.py
index d3612231c5..5bfac76282 100644
--- a/tests/units/test_state.py
+++ b/tests/units/test_state.py
@@ -41,6 +41,7 @@
 )
 from reflex.testing import chdir
 from reflex.utils import format, prerequisites, types
+from reflex.utils.exceptions import SetUndefinedStateVarError
 from reflex.utils.format import json_dumps
 from reflex.vars.base import ComputedVar, Var
 from tests.units.states.mutation import MutableSQLAModel, MutableTestState
@@ -3293,17 +3294,14 @@ def handle_var(self):
     state = State()  # type: ignore
     sub_state = Substate()  # type: ignore
 
-    with pytest.raises(AttributeError):
+    with pytest.raises(SetUndefinedStateVarError):
         state.handle_regular_var()
 
-    with pytest.raises(AttributeError):
+    with pytest.raises(SetUndefinedStateVarError):
         sub_state.handle_var()
 
-    # TODO: uncomment this if the case of backend vars are supported.
-    # with pytest.raises(AttributeError):
-    #     state.handle_backend_var()
-    #
-    # with pytest.raises(AttributeError):
-    #     state.handle_non_var()
+    with pytest.raises(SetUndefinedStateVarError):
+        state.handle_backend_var()
 
     state.handle_supported_regular_vars()
+    state.handle_non_var()

From fa8f7be00c90ea92fa8bcb78153432a5cde91eeb Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 3 Oct 2024 16:58:27 +0000
Subject: [PATCH 11/12] reorder if checks

---
 reflex/state.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/reflex/state.py b/reflex/state.py
index bd3cc79eaa..d3002e04a5 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1282,9 +1282,9 @@ def __setattr__(self, name: str, value: Any):
             return
 
         if (
-            not name.startswith("__")
+            name not in self.vars
+            and not name.startswith("__")
             and not name.startswith(f"_{type(self).__name__}__")
-            and name not in self.vars
             and name not in self.get_skip_vars()
         ):
             raise SetUndefinedStateVarError(

From 3d07437b63f161a15555e08bde03b30df4bf570c Mon Sep 17 00:00:00 2001
From: Elijah <elijahahianyo@gmail.com>
Date: Thu, 3 Oct 2024 17:00:55 +0000
Subject: [PATCH 12/12] final reorder

---
 reflex/state.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/reflex/state.py b/reflex/state.py
index d3002e04a5..64ea960e10 100644
--- a/reflex/state.py
+++ b/reflex/state.py
@@ -1283,9 +1283,9 @@ def __setattr__(self, name: str, value: Any):
 
         if (
             name not in self.vars
+            and name not in self.get_skip_vars()
             and not name.startswith("__")
             and not name.startswith(f"_{type(self).__name__}__")
-            and name not in self.get_skip_vars()
         ):
             raise SetUndefinedStateVarError(
                 f"The state variable '{name}' has not been defined in '{type(self).__name__}'. "