Allow None when using a Union containing Any or object (#3452)

* Add unit test for Union[int, Any]

* Allow None when Any or object is in Union

Resolves #3444

* Add changelog entry for #3444

* Prefer `is_none_type()` over `type_ is NoneType`

* fix(lint): remove useless import

Co-authored-by: PrettyWood <em.jolibois@gmail.com>

changes/3444-tharradine.md

@@ -0,0 +1 @@
+Fix issue where `None` was considered invalid when using a `Union` type containing `Any` or `object`

pydantic/fields.py

@@ -34,7 +34,6 @@
     Callable,
     ForwardRef,
     NoArgAnyCallable,
-    NoneType,
     display_as_type,
     get_args,
     get_origin,
@@ -574,10 +573,11 @@ def _type_analysis(self) -> None:  # noqa: C901 (ignore complexity)
         elif is_union(origin):
             types_ = []
             for type_ in get_args(self.type_):
-                if type_ is NoneType:
+                if is_none_type(type_) or type_ is Any or type_ is object:
                     if self.required is Undefined:
                         self.required = False
                     self.allow_none = True
+                if is_none_type(type_):
                     continue
                 types_.append(type_)
 

tests/test_edge_cases.py

@@ -83,6 +83,23 @@ class Model(BaseModel):
     ]
 
 
+def test_union_int_any():
+    class Model(BaseModel):
+        v: Union[int, Any]
+
+    m = Model(v=123)
+    assert m.v == 123
+
+    m = Model(v='123')
+    assert m.v == 123
+
+    m = Model(v='foobar')
+    assert m.v == 'foobar'
+
+    m = Model(v=None)
+    assert m.v is None
+
+
 def test_union_priority():
     class ModelOne(BaseModel):
         v: Union[int, str] = ...