fix: preserve backwards compatibility in generate_unique_id for route creation

fastapi/openapi/utils.py

@@ -33,7 +33,6 @@ from fastapi.types import ModelNameMap
 from fastapi.utils import (
     deep_dict_update,
     generate_operation_id_for_path,
-    get_openapi_operation_id,
     is_body_allowed_for_status_code,
 )
 from pydantic import BaseModel
@@ -243,7 +242,14 @@ def get_openapi_operation_metadata(
     operation["summary"] = generate_operation_summary(route=route, method=method)
     if route.description:
         operation["description"] = route.description
-    operation_id = route.operation_id or get_openapi_operation_id(route, method)
+    
+    # Start with explicit operation_id or unique_id
+    operation_id = route.operation_id or route.unique_id
+    
+    # For multi-method routes, append the method if the unique_id alone would be a duplicate
+    if operation_id in operation_ids:
+        operation_id = f"{route.unique_id}_{method.lower()}"
+    
     if operation_id in operation_ids:
         endpoint_name = getattr(route.endpoint, "__name__", "<unnamed_endpoint>")
         message = f"Duplicate Operation ID {operation_id} for function {endpoint_name}"

fastapi/utils.py

@@ -102,17 +102,6 @@ def generate_unique_id(route: APIRoute) -> str:
     return operation_id
 
 
-def get_openapi_operation_id(route: APIRoute, method: str) -> str:
-    """
-    Generate a unique operation ID for a specific HTTP method in the OpenAPI schema.
-    This ensures each HTTP method on a multi-method route gets a unique operation ID.
-    """
-    operation_id = f"{route.name}{route.path_format}"
-    operation_id = re.sub(r"\W", "_", operation_id)
-    operation_id = f"{operation_id}_{method.lower()}"
-    return operation_id
-
-
 def deep_dict_update(main_dict: dict[Any, Any], update_dict: dict[Any, Any]) -> None:
     for key, value in update_dict.items():
         if (