Merge pull request #98 from python-scim/prepatch

Implement PatchOp validation checks

Author: azmeuk

scim2_models/rfc7644/message.py

@@ -10,6 +10,8 @@
 from pydantic import Tag
 from pydantic._internal._model_construction import ModelMetaclass
 
+from scim2_models.rfc7643.resource import Resource
+
 from ..base import BaseModel
 from ..scim_object import ScimObject
 from ..utils import UNION_TYPES
@@ -108,3 +110,16 @@ def __new__(
 
         klass = super().__new__(cls, name, bases, attrs, **kwargs)
         return klass
+
+
+def get_resource_class(obj) -> Optional[type[Resource]]:
+    """Extract the resource class from generic type parameter."""
+    metadata = getattr(obj.__class__, "__pydantic_generic_metadata__", None)
+    if not metadata or not metadata.get("args"):
+        return None
+
+    resource_class = metadata["args"][0]
+    if isinstance(resource_class, type) and issubclass(resource_class, Resource):
+        return resource_class
+
+    return None

scim2_models/rfc7644/patch_op.py

@@ -1,16 +1,24 @@
 from enum import Enum
 from typing import Annotated
 from typing import Any
+from typing import Generic
 from typing import Optional
 
 from pydantic import Field
 from pydantic import field_validator
 from pydantic import model_validator
 from typing_extensions import Self
 
+from ..annotations import Mutability
 from ..annotations import Required
 from ..attributes import ComplexAttribute
+from ..base import BaseModel
+from ..rfc7643.resource import AnyResource
+from ..utils import extract_field_name
+from ..utils import validate_scim_path_syntax
+from .error import Error
 from .message import Message
+from .message import get_resource_class
 
 
 class PatchOperation(ComplexAttribute):
@@ -34,15 +42,67 @@ class Op(str, Enum):
     """The "path" attribute value is a String containing an attribute path
     describing the target of the operation."""
 
-    @model_validator(mode="after")
-    def validate_path(self) -> Self:
-        # The "path" attribute value is a String containing an attribute path
-        # describing the target of the operation. The "path" attribute is
-        # OPTIONAL for "add" and "replace" and is REQUIRED for "remove"
-        # operations. See relevant operation sections below for details.
+    @field_validator("path")
+    @classmethod
+    def validate_path_syntax(cls, v: Optional[str]) -> Optional[str]:
+        """Validate path syntax according to RFC 7644 ABNF grammar (simplified)."""
+        if v is None:
+            return v
+
+        # RFC 7644 Section 3.5.2: Path syntax validation according to ABNF grammar
+        if not validate_scim_path_syntax(v):
+            raise ValueError(Error.make_invalid_path_error().detail)
+
+        return v
+
+    def _validate_mutability(
+        self, resource_class: type[BaseModel], field_name: str
+    ) -> None:
+        """Validate mutability constraints."""
+        # RFC 7644 Section 3.5.2: Servers should be tolerant of schema extensions
+        if field_name not in resource_class.model_fields:
+            return
+
+        mutability = resource_class.get_field_annotation(field_name, Mutability)
 
+        # RFC 7643 Section 7: Attributes with mutability "readOnly" SHALL NOT be modified
+        if mutability == Mutability.read_only:
+            if self.op in (PatchOperation.Op.add, PatchOperation.Op.replace_):
+                raise ValueError(Error.make_mutability_error().detail)
+
+        # RFC 7643 Section 7: Attributes with mutability "immutable" SHALL NOT be updated
+        elif mutability == Mutability.immutable:
+            if self.op == PatchOperation.Op.replace_:
+                raise ValueError(Error.make_mutability_error().detail)
+
+    def _validate_required_attribute(
+        self, resource_class: type[BaseModel], field_name: str
+    ) -> None:
+        """Validate required attribute constraints for remove operations."""
+        # RFC 7644 Section 3.5.2.3: Only validate for remove operations
+        if self.op != PatchOperation.Op.remove:
+            return
+
+        # RFC 7644 Section 3.5.2: Servers should be tolerant of schema extensions
+        if field_name not in resource_class.model_fields:
+            return
+
+        required = resource_class.get_field_annotation(field_name, Required)
+
+        # RFC 7643 Section 7: Required attributes SHALL NOT be removed
+        if required == Required.true:
+            raise ValueError(Error.make_invalid_value_error().detail)
+
+    @model_validator(mode="after")
+    def validate_operation_requirements(self) -> Self:
+        """Validate operation requirements according to RFC 7644."""
+        # RFC 7644 Section 3.5.2.3: Path is required for remove operations
         if self.path is None and self.op == PatchOperation.Op.remove:
-            raise ValueError("Op.path is required for remove operations")
+            raise ValueError(Error.make_invalid_value_error().detail)
+
+        # RFC 7644 Section 3.5.2.1: Value is required for "add" operations
+        if self.op == PatchOperation.Op.add and self.value is None:
+            raise ValueError(Error.make_invalid_value_error().detail)
 
         return self
 
@@ -51,7 +111,7 @@ def validate_path(self) -> Self:
     @field_validator("op", mode="before")
     @classmethod
     def normalize_op(cls, v: Any) -> Any:
-        """Ignorecase for op.
+        """Ignore case for op.
 
         This brings
         `compatibility with Microsoft Entra <https://learn.microsoft.com/en-us/entra/identity/app-provisioning/use-scim-to-provision-users-and-groups#general>`_:
@@ -65,13 +125,8 @@ def normalize_op(cls, v: Any) -> Any:
         return v
 
 
-class PatchOp(Message):
-    """Patch Operation as defined in :rfc:`RFC7644 §3.5.2 <7644#section-3.5.2>`.
-
-    .. todo::
-
-        The models for Patch operations are defined, but their behavior is not implemented nor tested yet.
-    """
+class PatchOp(Message, Generic[AnyResource]):
+    """Patch Operation as defined in :rfc:`RFC7644 §3.5.2 <7644#section-3.5.2>`."""
 
     schemas: Annotated[list[str], Required.true] = [
         "urn:ietf:params:scim:api:messages:2.0:PatchOp"
@@ -82,3 +137,27 @@ class PatchOp(Message):
     )
     """The body of an HTTP PATCH request MUST contain the attribute
     "Operations", whose value is an array of one or more PATCH operations."""
+
+    @model_validator(mode="after")
+    def validate_operations(self) -> Self:
+        """Validate operations against resource type metadata if available.
+
+        When PatchOp is used with a specific resource type (e.g., PatchOp[User]),
+        this validator will automatically check mutability and required constraints.
+        """
+        resource_class = get_resource_class(self)
+        if resource_class is None or not self.operations:
+            return self
+
+        for operation in self.operations:
+            if operation.path is None:
+                continue
+
+            field_name = extract_field_name(operation.path)
+            if field_name is None:
+                continue
+
+            operation._validate_mutability(resource_class, field_name)
+            operation._validate_required_attribute(resource_class, field_name)
+
+        return self

scim2_models/utils.py

@@ -156,3 +156,30 @@ def validate_scim_urn_syntax(path: str) -> bool:
         return False
 
     return True
+
+
+def extract_field_name(path: str) -> Optional[str]:
+    """Extract the field name from a path.
+
+    For now, only handle simple paths (no filters, no complex expressions).
+    Returns None for complex paths that require filter parsing.
+
+    """
+    # Handle URN paths
+    if path.startswith("urn:"):
+        # First validate it's a proper URN
+        if not validate_scim_urn_syntax(path):
+            return None
+        parts = path.rsplit(":", 1)
+        return parts[1]
+
+    # Handle simple paths (no brackets, no filters)
+    if "[" in path or "]" in path:
+        return None  # Complex filter path, not handled
+
+    # Simple attribute path (may have dots for sub-attributes)
+    # For now, just take the first part before any dot
+    if "." in path:
+        return path.split(".")[0]
+
+    return path