Support PEP 604 union annotations (#256)

Author: dnnsthnnr

temporalio/converter.py

@@ -49,6 +49,9 @@
 if sys.version_info >= (3, 11):
     from enum import StrEnum
 
+if sys.version_info >= (3, 10):
+    from types import UnionType
+
 
 class PayloadConverter(ABC):
     """Base payload converter to/from multiple payloads/values."""
@@ -1155,8 +1158,12 @@ def value_to_type(hint: Type, value: Any) -> Any:
             raise TypeError(f"Value {value} not in literal values {type_args}")
         return value
 
+    is_union = origin is Union
+    if sys.version_info >= (3, 10):
+        is_union = is_union or isinstance(origin, UnionType)
+
     # Union
-    if origin is Union:
+    if is_union:
         # Try each one. Note, Optional is just a union w/ none.
         for arg in type_args:
             try:

tests/test_converter.py

@@ -305,6 +305,12 @@ def fail(hint: Type, value: Any) -> None:
     ok(Union[int, str], "foo")
     ok(Union[MyDataClass, NestedDataClass], MyDataClass("foo", 5, SerializableEnum.FOO))
     ok(Union[MyDataClass, NestedDataClass], NestedDataClass("foo"))
+    if sys.version_info >= (3, 10):
+        ok(int | None, None)
+        ok(int | None, 5)
+        fail(int | None, "1")
+        ok(MyDataClass | NestedDataClass, MyDataClass("foo", 5, SerializableEnum.FOO))
+        ok(MyDataClass | NestedDataClass, NestedDataClass("foo"))
 
     # NewType
     ok(NewIntType, 5)