From c26c3b9e6379fd89cc8e5b6d5d5b75ac4370352f Mon Sep 17 00:00:00 2001
From: jasonrock-a3 <107961397+jasonrock-a3@users.noreply.github.com>
Date: Mon, 27 Nov 2023 11:44:00 -0800
Subject: [PATCH] Fixes catchall inheritance issue (#500)

---
 dataclasses_json/undefined.py      |  2 +-
 tests/test_undefined_parameters.py | 20 +++++++++++++++++++-
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/dataclasses_json/undefined.py b/dataclasses_json/undefined.py
index d896bb79..cb8b2cfc 100644
--- a/dataclasses_json/undefined.py
+++ b/dataclasses_json/undefined.py
@@ -198,7 +198,7 @@ def _get_default(catch_all_field: Field) -> Any:
     @staticmethod
     def handle_to_dict(obj, kvs: Dict[Any, Any]) -> Dict[Any, Any]:
         catch_all_field = \
-            _CatchAllUndefinedParameters._get_catch_all_field(obj)
+            _CatchAllUndefinedParameters._get_catch_all_field(obj.__class__)
         undefined_parameters = kvs.pop(catch_all_field.name)
         if isinstance(undefined_parameters, dict):
             kvs.update(
diff --git a/tests/test_undefined_parameters.py b/tests/test_undefined_parameters.py
index 58740dcb..bac711af 100644
--- a/tests/test_undefined_parameters.py
+++ b/tests/test_undefined_parameters.py
@@ -383,4 +383,22 @@ class UnknownAPIDumpDefault:
         catch_all: CatchAll = field(default_factory=dict)
 
     dump = UnknownAPIDumpDefault(**valid_response)
-    assert dump.catch_all == {}
\ No newline at end of file
+    assert dump.catch_all == {}
+
+
+def test_undefined_inheritance():
+    @dataclass_json(undefined=Undefined.INCLUDE)
+    @dataclass
+    class TestInternalConfig:
+        options: CatchAll = None
+        val: str = "bar"
+        val2: int = 0
+
+    @dataclass_json
+    @dataclass
+    class TestInternalExtendConfig(TestInternalConfig):
+        val: str = "baz"
+
+    tie = TestInternalExtendConfig()
+    tie.to_dict()
+