fix: Python 3.9 compatibility

UnionType does not exist in Python 3.9

Author: azmeuk

doc/changelog.rst

@@ -1,6 +1,13 @@
 Changelog
 =========
 
+[0.2.4] - Unreleased
+--------------------
+
+Fixed
+^^^^^
+- Python 3.9 compatibility.
+
 [0.2.3] - 2024-11-01
 --------------------
 

pyproject.toml

@@ -65,6 +65,7 @@ exclude_lines = [
     "@pytest.mark.skip",
     "pragma: no cover",
     "raise NotImplementedError",
+    "except ImportError",
 ]
 
 [tool.ruff.lint]

scim2_models/base.py

@@ -2,7 +2,6 @@
 from enum import Enum
 from enum import auto
 from inspect import isclass
-from types import UnionType
 from typing import Annotated
 from typing import Any
 from typing import Generic
@@ -33,6 +32,14 @@
 from scim2_models.utils import normalize_attribute_name
 from scim2_models.utils import to_camel
 
+try:
+    from types import UnionType
+
+    UNION_TYPES = [Union, UnionType]
+except ImportError:
+    # Python 3.9 has no UnionType
+    UNION_TYPES = [Union]
+
 ReferenceTypes = TypeVar("ReferenceTypes")
 URIReference = NewType("URIReference", str)
 ExternalReference = NewType("ExternalReference", str)
@@ -438,7 +445,7 @@ def get_field_root_type(cls, attribute_name: str) -> type:
         attribute_type = cls.model_fields[attribute_name].annotation
 
         # extract 'x' from 'Optional[x]'
-        if get_origin(attribute_type) in (Union, UnionType):
+        if get_origin(attribute_type) in UNION_TYPES:
             attribute_type = get_args(attribute_type)[0]
 
         # extract 'x' from 'List[x]'