Add support for explicit empty schemas

There might be a decorator explicitly stating the schema is empty
meaning there is no body (this is different from schema with type
"null"). In order to differentiate the empty schema from not set add a
similar Sentinet `UNSET` as in OpenStackSDK and generate dummy schemas
only when the schema is really unknown.

Change-Id: I72434afea54af9aa6df205a27a8d66765bb0ffd7

codegenerator/openapi/base.py

@@ -18,7 +18,7 @@ import importlib
 import inspect
 import logging
 from pathlib import Path
-from typing import Any, Callable
+from typing import Any, Callable, Literal
 import re
 
 from codegenerator.common.schema import ParameterSchema
@@ -35,6 +35,16 @@ from wsme import types as wtypes
 VERSION_RE = re.compile(r"[Vv][0-9\.]*")
 
 
+# Workaround Python's lack of an undefined sentinel
+# https://python-patterns.guide/python/sentinel-object/
+class Unset:
+    def __bool__(self) -> Literal[False]:
+        return False
+
+
+UNSET: Unset = Unset()
+
+
 def get_referred_type_data(func, name: str):
     """Get python type object referred by the function
 
@@ -893,9 +903,9 @@ class OpenStackServerSourceBase:
         mode,
         action_name,
     ):
-        op_body = operation_spec.requestBody.setdefault("content", {})
         mime_type: str = "application/json"
         schema_name = None
+        schema_ref: str | Unset | None = None
         # We should not modify path_resource_names of the caller
         path_resource_names = path_resource_names.copy()
         # Create container schema with version discriminator
@@ -909,9 +919,13 @@ class OpenStackServerSourceBase:
 
         if len(body_schemas) == 1:
             # There is only one body known at the moment
+            # None is a special case with explicitly no body supported
+            if body_schemas[0] is not UNSET:
                 if cont_schema_name in openapi_spec.components.schemas:
                     # if we have already oneOf - add there
-                cont_schema = openapi_spec.components.schemas[cont_schema_name]
+                    cont_schema = openapi_spec.components.schemas[
+                        cont_schema_name
+                    ]
                     if cont_schema.oneOf and body_schemas[0] not in [
                         x["$ref"] for x in cont_schema.oneOf
                     ]:
@@ -922,6 +936,7 @@ class OpenStackServerSourceBase:
                     schema_ref = body_schemas[0]
         elif len(body_schemas) > 1:
             # We may end up here multiple times if we have versioned operation. In this case merge to what we have already
+            op_body = operation_spec.requestBody.setdefault("content", {})
             old_schema = op_body.get(mime_type, {}).get("schema", {})
             old_ref = (
                 old_schema.ref
@@ -984,16 +999,20 @@ class OpenStackServerSourceBase:
             )
 
         if mode == "action":
+            op_body = operation_spec.requestBody.setdefault("content", {})
             js_content = op_body.setdefault(mime_type, {})
             body_schema = js_content.setdefault("schema", {})
             one_of = body_schema.setdefault("oneOf", [])
-            if schema_ref not in [x.get("$ref") for x in one_of]:
+            if schema_ref and schema_ref not in [
+                x.get("$ref") for x in one_of
+            ]:
                 one_of.append({"$ref": schema_ref})
             os_ext = body_schema.setdefault("x-openstack", {})
             os_ext["discriminator"] = "action"
             if cont_schema and action_name:
                 cont_schema.openstack["action-name"] = action_name
-        elif schema_ref:
+        elif schema_ref is not None and schema_ref is not UNSET:
+            op_body = operation_spec.requestBody.setdefault("content", {})
             js_content = op_body.setdefault(mime_type, {})
             body_schema = js_content.setdefault("schema", {})
             operation_spec.requestBody["content"][mime_type]["schema"] = (
@@ -1127,6 +1146,7 @@ class OpenStackServerSourceBase:
                 "type": "object",
                 "description": LiteralScalarString(description),
             }
+        if schema_def is not UNSET:
             schema = openapi_spec.components.schemas.setdefault(
                 name,
                 TypeSchema(
@@ -1180,9 +1200,9 @@ class OpenStackServerSourceBase:
         """Extract schemas from the decorated method."""
         # Unwrap operation decorators to access all properties
         expected_errors: list[str] = []
-        body_schemas: list[str] = []
+        body_schemas: list[str | Unset] = []
         query_params_versions: list[tuple] = []
-        response_body_schema: dict | None = None
+        response_body_schema: dict | Unset | None = UNSET
 
         f = func
         while hasattr(f, "__wrapped__"):
@@ -1214,15 +1234,21 @@ class OpenStackServerSourceBase:
                     "request_body_schema",
                     getattr(f, "_request_body_schema", {}),
                 )
+                if obj is not None:
                     if obj.get("type") in ["object", "array"]:
                         # We only allow object and array bodies
                         # To prevent type name collision keep module name part of the name
                         typ_name = (
                             "".join([x.title() for x in path_resource_names])
                             + func.__name__.title()
-                        + (f"_{min_ver.replace('.', '')}" if min_ver else "")
+                            + (
+                                f"_{min_ver.replace('.', '')}"
+                                if min_ver
+                                else ""
                             )
-                    comp_schema = openapi_spec.components.schemas.setdefault(
+                        )
+                        comp_schema = (
+                            openapi_spec.components.schemas.setdefault(
                                 typ_name,
                                 self._sanitize_schema(
                                     copy.deepcopy(obj),
@@ -1230,6 +1256,7 @@ class OpenStackServerSourceBase:
                                     end_version=end_version,
                                 ),
                             )
+                        )
 
                         if min_ver:
                             if not comp_schema.openstack:
@@ -1246,6 +1273,8 @@ class OpenStackServerSourceBase:
 
                         ref_name = f"#/components/schemas/{typ_name}"
                         body_schemas.append(ref_name)
+                else:
+                    body_schemas.append(UNSET)
 
             if "response_body_schema" in closure_locals or hasattr(
                 f, "_response_body_schema"
@@ -1255,7 +1284,10 @@ class OpenStackServerSourceBase:
                     "response_body_schema",
                     getattr(f, "_response_body_schema", {}),
                 )
+                if obj is not None:
                     response_body_schema = obj
+                else:
+                    response_body_schema = UNSET
             if "query_params_schema" in closure_locals or hasattr(
                 f, "_request_query_schema"
             ):

codegenerator/openapi/keystone.py

@@ -10,7 +10,6 @@
 #   License for the specific language governing permissions and limitations
 #   under the License.
 #
-import copy
 import inspect
 from multiprocessing import Process
 import logging
@@ -22,7 +21,7 @@ from codegenerator.common.schema import ParameterSchema
 from codegenerator.common.schema import PathSchema
 from codegenerator.common.schema import SpecSchema
 from codegenerator.common.schema import TypeSchema
-from codegenerator.openapi.base import OpenStackServerSourceBase
+from codegenerator.openapi.base import OpenStackServerSourceBase, UNSET
 from codegenerator.openapi.keystone_schemas import application_credential
 from codegenerator.openapi.keystone_schemas import auth
 from codegenerator.openapi.keystone_schemas import common
@@ -368,7 +367,7 @@ class KeystoneGenerator(OpenStackServerSourceBase):
         start_version = None
         end_version = None
         deser_schema: dict = {}
-        ser_schema: dict = {}
+        ser_schema: dict | None = {}
 
         (
             query_params_versions,
@@ -512,7 +511,7 @@ class KeystoneGenerator(OpenStackServerSourceBase):
         # Invoke modularized schema _get_schema_ref
         for resource_mod in self.RESOURCE_MODULES:
             hook = getattr(resource_mod, "_get_schema_ref", None)
-            if hook:
+            if hook and schema_def is not UNSET:
                 (ref, mime_type, matched) = hook(
                     openapi_spec, name, description, schema_def, action_name
                 )
@@ -527,5 +526,4 @@ class KeystoneGenerator(OpenStackServerSourceBase):
             schema_def=schema_def,
             action_name=action_name,
         )
-
         return (ref, mime_type)