Add StrEnum conversion support (#177)

Fixes #176

Author: KMilhan

README.md

@@ -188,7 +188,7 @@ The default data converter supports converting multiple types including:
   * Iterables including ones JSON dump may not support by default, e.g. `set`
   * Any class with a `dict()` method and a static `parse_obj()` method, e.g.
     [Pydantic models](https://pydantic-docs.helpmanual.io/usage/models)
-  * [IntEnum](https://docs.python.org/3/library/enum.html) based enumerates
+  * [IntEnum, StrEnum](https://docs.python.org/3/library/enum.html) based enumerates
 
 For converting from JSON, the workflow/activity type hint is taken into account to convert to the proper type. Care has
 been taken to support all common typings including `Optional`, `Union`, all forms of iterables and mappings, `NewType`,

temporalio/converter.py

@@ -7,6 +7,7 @@
 import dataclasses
 import inspect
 import json
+import sys
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
 from datetime import datetime
@@ -33,6 +34,10 @@
 import temporalio.api.common.v1
 import temporalio.common
 
+# StrEnum is available in 3.11+
+if sys.version_info >= (3, 11):
+    from enum import StrEnum
+
 
 class PayloadConverter(ABC):
     """Base payload converter to/from multiple payloads/values."""
@@ -874,6 +879,15 @@ def value_to_type(hint: Type, value: Any) -> Any:
             )
         return hint(value)
 
+    # StrEnum, available in 3.11+
+    if sys.version_info >= (3, 11):
+        if inspect.isclass(hint) and issubclass(hint, StrEnum):
+            if not isinstance(value, str):
+                raise TypeError(
+                    f"Cannot convert to enum {hint}, value not a string, value is {type(value)}"
+                )
+            return hint(value)
+
     # Iterable. We intentionally put this last as it catches several others.
     if inspect.isclass(origin) and issubclass(origin, collections.abc.Iterable):
         if not isinstance(value, collections.abc.Iterable):

tests/test_converter.py

@@ -33,6 +33,10 @@
 import temporalio.converter
 from temporalio.api.common.v1 import Payload as AnotherNameForPayload
 
+# StrEnum is available in 3.11+
+if sys.version_info >= (3, 11):
+    from enum import StrEnum
+
 
 class NonSerializableClass:
     pass
@@ -46,6 +50,12 @@ class SerializableEnum(IntEnum):
     FOO = 1
 
 
+if sys.version_info >= (3, 11):
+
+    class SerializableStrEnum(StrEnum):
+        FOO = "foo"
+
+
 @dataclass
 class MyDataClass:
     foo: str
@@ -107,8 +117,8 @@ async def assert_payload(
         await assert_payload(NonSerializableClass(), None, None)
     assert "not JSON serializable" in str(excinfo.value)
 
-    # Bad enum type. We do not allow non-int enums due to ambiguity in
-    # rebuilding and other confusion.
+    # Bad enum type. We do not allow non-int or non-str enums due to ambiguity
+    # in rebuilding and other confusion.
     with pytest.raises(TypeError) as excinfo:
         await assert_payload(NonSerializableEnum.FOO, None, None)
     assert "not JSON serializable" in str(excinfo.value)
@@ -295,6 +305,15 @@ def fail(hint: Type, value: Any) -> None:
     ok(SerializableEnum, SerializableEnum.FOO)
     ok(List[SerializableEnum], [SerializableEnum.FOO, SerializableEnum.FOO])
 
+    # StrEnum is available in 3.11+
+    if sys.version_info >= (3, 11):
+        # StrEnum
+        ok(SerializableStrEnum, SerializableStrEnum.FOO)
+        ok(
+            List[SerializableStrEnum],
+            [SerializableStrEnum.FOO, SerializableStrEnum.FOO],
+        )
+
     # 3.10+ checks
     if sys.version_info >= (3, 10):
         ok(list[int], [1, 2])