jambo/parser/anyof_type_parser.py

@@ -34,8 +34,34 @@ class AnyOfTypeParser(GenericTypeParser):
         # By defining the type as Union of Annotated type we can use the Field validator
         # to enforce the constraints of each union type when needed.
         # We use Annotated to attach the Field validators to the type.
+        # Only wrap in Annotated[T, Field(**v)] if there are meaningful field constraints
+        # Don't wrap for simple cases where v only contains {'default': None}
         field_types = [
-            Annotated[t, Field(**v)] if v is not None else t for t, v in sub_types
+            Annotated[t, Field(**v)] if self._has_meaningful_constraints(v) else t
+            for t, v in sub_types
         ]
 
         return Union[(*field_types,)], mapped_properties
+
+    @staticmethod
+    def _has_meaningful_constraints(field_props):
+        """
+        Check if field properties contain meaningful constraints that require Field wrapping.
+
+        Returns False if:
+        - field_props is None or empty
+        - field_props only contains {'default': None}
+
+        Returns True if:
+        - field_props contains a non-None default value
+        - field_props contains other constraint properties (min_length, max_length, pattern, etc.)
+        """
+        if not field_props:
+            return False
+
+        # If only default is set and it's None, no meaningful constraints
+        if len(field_props) == 1 and field_props.get('default') is None:
+            return False
+
+        # If there are multiple properties or non-None default, that's meaningful
+        return True

tests/parser/test_anyof_type_parser.py

@@ -46,11 +46,8 @@ class TestAnyOfTypeParser(TestCase):
 
         type_1, type_2 = get_args(type_parsing)
 
-        self.assertEqual(get_origin(type_1), Annotated)
+        self.assertEqual(type_1, str)
-        self.assertIn(str, get_args(type_1))
+        self.assertEqual(type_2, int)
-
-        self.assertEqual(get_origin(type_2), Annotated)
-        self.assertIn(int, get_args(type_2))
 
     def test_any_of_string_or_int_with_default(self):
         """
@@ -74,11 +71,8 @@ class TestAnyOfTypeParser(TestCase):
 
         type_1, type_2 = get_args(type_parsing)
 
-        self.assertEqual(get_origin(type_1), Annotated)
+        self.assertEqual(type_1, str)
-        self.assertIn(str, get_args(type_1))
+        self.assertEqual(type_2, int)
-
-        self.assertEqual(get_origin(type_2), Annotated)
-        self.assertIn(int, get_args(type_2))
 
         self.assertEqual(type_validator["default"], 42)