fix: handle "optional" marker in ucp_request schema preprocessing (#33)

Co-authored-by: Federico D'Amato <damaz@google.com>

Author: xiaoxuanz-hub

preprocess_schemas.py

@@ -306,12 +306,18 @@ def eval_prop_inclusion(name, data, op, base_required):
         include = False
     elif marker == "required":
         is_required = True
+    elif marker == "optional":
+        # A simple string "optional" marker overrides the base schema's required list for all operations.
+        is_required = False
     elif isinstance(marker, dict):
         val = marker.get(op)
         if val == "omit" or val is None:
             include = False
         elif val == "required":
             is_required = True
+        elif val == "optional":
+            # Override base schema's required list when a field is explicitly marked optional for a specific operation.
+            is_required = False
 
     return include, is_required
 

src/ucp_sdk/models/schemas/shopping/types/fulfillment_method_create_request.py

@@ -40,7 +40,7 @@ class FulfillmentMethodCreateRequest(BaseModel):
     """
     Fulfillment method type.
     """
-    line_item_ids: list[str]
+    line_item_ids: list[str] | None = None
     """
     Line item IDs fulfilled via this method.
     """

src/ucp_sdk/models/schemas/shopping/types/line_item_update_request.py

@@ -31,7 +31,7 @@ class LineItemUpdateRequest(BaseModel):
     model_config = ConfigDict(
         extra="allow",
     )
-    id: str
+    id: str | None = None
     item: item_update_request.ItemUpdateRequest
     quantity: int = Field(..., ge=1)
     """

src/ucp_sdk/models/schemas/shopping/types/shipping_destination_create_request.py

@@ -31,7 +31,7 @@ class ShippingDestinationCreateRequest(PostalAddress):
     model_config = ConfigDict(
         extra="allow",
     )
-    id: str
+    id: str | None = None
     """
     ID specific to this shipping destination.
     """

src/ucp_sdk/models/schemas/shopping/types/shipping_destination_update_request.py

@@ -31,7 +31,7 @@ class ShippingDestinationUpdateRequest(PostalAddress):
     model_config = ConfigDict(
         extra="allow",
     )
-    id: str
+    id: str | None = None
     """
     ID specific to this shipping destination.
     """