fix: serialize typing classes assigned to fields

langfuse/serializer.py

@@ -6,6 +6,7 @@
 import enum
 from json import JSONEncoder
 from typing import Any
+import typing
 from uuid import UUID
 from collections.abc import Sequence
 from langfuse.api.core import serialize_datetime
@@ -107,6 +108,13 @@ def default(self, obj: Any):
             if isinstance(obj, Sequence):
                 return [self.default(item) for item in obj]
 
+            # typing.get_origin only available in Python 3.8 and above
+            try:
+                if isinstance(obj, type) or typing.get_origin(obj) is not None:
+                    return f"<{getattr(obj, 'name', str(obj))}>"
+            except Exception:
+                pass
+
             if hasattr(obj, "__slots__"):
                 return self.default(
                     {slot: getattr(obj, slot, None) for slot in obj.__slots__}

tests/test_serializer.py

@@ -1,4 +1,5 @@
 from datetime import datetime, date, timezone
+import typing
 from uuid import UUID
 from enum import Enum
 from dataclasses import dataclass
@@ -182,6 +183,17 @@ def __init__(self):
     assert json.loads(serializer.encode(obj)) == {"field": "value"}
 
 
+def test_slots_types():
+    class SlotClass:
+        def __init__(self):
+            self.something = typing.Sequence[int]
+
+    obj = SlotClass()
+
+    serializer = EventSerializer()
+    assert json.loads(serializer.encode(obj)) == {"something": "<typing.Sequence[int]>"}
+
+
 def test_numpy_float32():
     import numpy as np