chore: fix Pydantic warning

PydanticDeprecatedSince211: Accessing this attribute on the instance is deprecated, and will be removed in Pydantic V3. Instead, you should access this attribute from the model class. Deprecated in Pydantic V2.11 to be removed in V3.0.

Author: azmeuk

scim2_server/utils.py

@@ -3,6 +3,7 @@
 import json
 import re
 import sys
+from inspect import isclass
 from typing import Any
 
 from pydantic import EmailStr
@@ -71,7 +72,9 @@ def merge_resources(target: Resource, updates: BaseModel):
         setattr(target, set_attribute, new_value)
 
 
-def get_by_alias(r: BaseModel, scim_name: str, allow_none: bool = False) -> str | None:
+def get_by_alias(
+    resource: BaseModel, scim_name: str, allow_none: bool = False
+) -> str | None:
     """Return the pydantic attribute name for a BaseModel and given SCIM attribute name.
 
     :param r: BaseModel
@@ -81,16 +84,17 @@ def get_by_alias(r: BaseModel, scim_name: str, allow_none: bool = False) -> str
     :raises SCIMException: If no attribute is found and allow_none is
         False
     """
+    klass = resource.__class__ if not isclass(resource) else resource
     try:
         return next(
-            k
-            for k, v in r.model_fields.items()
-            if v.serialization_alias.lower() == scim_name.lower()
+            key
+            for key, value in klass.model_fields.items()
+            if value.serialization_alias.lower() == scim_name.lower()
         )
-    except StopIteration as e:
+    except StopIteration as exc:
         if allow_none:
             return None
-        raise SCIMException(Error.make_no_target_error()) from e
+        raise SCIMException(Error.make_no_target_error()) from exc
 
 
 def get_schemas(resource: Resource) -> list[str]:
@@ -99,7 +103,7 @@ def get_schemas(resource: Resource) -> list[str]:
     Note that this may include schemas the resource does not currently
     have (such as missing optional schema extensions).
     """
-    return resource.model_fields["schemas"].default
+    return resource.__class__.model_fields["schemas"].default
 
 
 def get_or_create(