Support PEP 604 unions, types.UnionType (#184)

* Support PEP 604 unions, types.UnionType

* Refactor

* fix

* Add changelog entry

Co-authored-by: Konrad Hałas <halas.konrad@gmail.com>

CHANGELOG.md

@@ -11,6 +11,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add explicit `__all__` configuration
 - Add Python 3.10 and 3.11 support
+- Support [PEP 604] unions through `types.UnionType`
+
+[PEP 604]: https://peps.python.org/pep-0604/
 
 ### Fixed
 

dacite/types.py

@@ -63,7 +63,15 @@ def is_generic(type_: Type) -> bool:
 
 
 def is_union(type_: Type) -> bool:
-    return is_generic(type_) and type_.__origin__ == Union
+    if is_generic(type_) and type_.__origin__ == Union:
+        return True
+
+    try:
+        from types import UnionType  # type: ignore
+
+        return isinstance(type_, UnionType)
+    except ImportError:
+        return False
 
 
 def is_literal(type_: Type) -> bool:

tests/common.py

@@ -3,3 +3,4 @@
 import pytest
 
 literal_support = init_var_type_support = pytest.mark.skipif(sys.version_info < (3, 8), reason="requires Python 3.8")
+pep_604_support = pytest.mark.skipif(sys.version_info < (3, 10), reason="requires Python 3.10")

tests/test_types.py

@@ -21,7 +21,7 @@
     is_type_generic,
     is_set,
 )
-from tests.common import literal_support, init_var_type_support
+from tests.common import literal_support, init_var_type_support, pep_604_support
 
 
 def test_is_union_with_union():
@@ -32,6 +32,11 @@ def test_is_union_with_non_union():
     assert not is_union(int)
 
 
+@pep_604_support
+def test_is_union_with_pep_604_union():
+    assert is_union(int | float)
+
+
 @literal_support
 def test_is_literal_with_literal():
     from typing import Literal
@@ -63,6 +68,16 @@ def test_is_optional_with_optional_of_union():
     assert is_optional(Optional[Union[int, float]])
 
 
+@pep_604_support
+def test_is_optional_with_pep_604_union():
+    assert is_optional(int | float | None)
+
+
+@pep_604_support
+def test_is_optional_with_non_optional_pep_604_union():
+    assert not is_optional(int | float)
+
+
 def test_extract_optional():
     assert extract_optional(Optional[int]) == int