refactor: implement BaseModel.get_field_multiplicity

Author: azmeuk

scim2_models/base.py

@@ -7,7 +7,6 @@
 from typing import Generic
 from typing import Optional
 from typing import TypeVar
-from typing import Union
 from typing import get_args
 from typing import get_origin
 
@@ -32,13 +31,7 @@
 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]
+from .utils import UNION_TYPES
 
 ReferenceTypes = TypeVar("ReferenceTypes")
 URIReference = NewType("URIReference", str)
@@ -456,6 +449,18 @@ def get_field_root_type(cls, attribute_name: str) -> type:
 
         return attribute_type
 
+    @classmethod
+    def get_field_multiplicity(cls, attribute_name: str) -> bool:
+        """Indicate whether a field holds multiple values."""
+        attribute_type = cls.model_fields[attribute_name].annotation
+
+        # extract 'x' from 'Optional[x]'
+        if get_origin(attribute_type) in UNION_TYPES:
+            attribute_type = get_args(attribute_type)[0]
+
+        origin = get_origin(attribute_type)
+        return isinstance(origin, type) and issubclass(origin, list)
+
     @field_validator("*")
     @classmethod
     def check_request_attributes_mutability(

scim2_models/rfc7643/resource.py

@@ -245,10 +245,6 @@ def from_schema(cls, schema) -> "Resource":
 AnyResource = TypeVar("AnyResource", bound="Resource")
 
 
-def is_multiple(field):
-    return "list" in str(field.annotation).lower()
-
-
 def dedicated_attributes(model):
     """Return attributes that are not members of parent classes."""
 
@@ -332,7 +328,7 @@ def model_attribute_to_attribute(model, attribute_name):
     return Attribute(
         name=field_info.serialization_alias or attribute_name,
         type=attribute_type,
-        multi_valued=is_multiple(field_info),
+        multi_valued=model.get_field_multiplicity(attribute_name),
         description=field_info.description,
         canonical_values=field_info.examples,
         required=model.get_field_annotation(attribute_name, Required),

scim2_models/utils.py

@@ -1,8 +1,17 @@
 import re
 from typing import Optional
+from typing import Union
 
 from pydantic.alias_generators import to_snake
 
+try:
+    from types import UnionType
+
+    UNION_TYPES = [Union, UnionType]
+except ImportError:
+    # Python 3.9 has no UnionType
+    UNION_TYPES = [Union]
+
 
 def int_to_str(status: Optional[int]) -> Optional[str]:
     return None if status is None else str(status)