fix: attribute types detection

canaille/backends/models.py

@@ -4,6 +4,7 @@ import typing
 from collections import ChainMap
 from typing import Annotated
 from typing import ClassVar
+from typing import Union
 from typing import get_origin
 from typing import get_type_hints
 
@@ -11,6 +12,14 @@ from canaille.app import classproperty
 from canaille.app import models
 from canaille.backends import Backend
 
+try:
+    from types import UnionType  # type: ignore
+
+    UNION_TYPES = [Union, UnionType]
+except ImportError:
+    # Python 3.9 has no UnionType
+    UNION_TYPES = [Union]
+
 
 class Model:
     """The model abstract class.
@@ -100,6 +109,13 @@ class BackendModel:
             else annotations
         )
 
+        # Extract the Optional and Union type
+        attribute_type = (
+            typing.get_args(attribute_type)[0]
+            if typing.get_origin(attribute_type) in UNION_TYPES
+            else attribute_type
+        )
+
         # Extract the Annotated annotation
         attribute_type, metadata = (
             typing.get_args(attribute_type)