Runtime Mode does not seem to keep Optional attribute to Recursive Fields

[Levak]

Describe the bug

Using protobuf_to_pydantic in runtime mode (i.e. using msg_to_pydantic_model) yields a class that seems to trigger a validation error when optional message fields are missing. I have not tested with plugin mode as I need a specific version of protobuf.

Dependencies

• Python 3.8.2
• protobuf_to_pydantic 0.3.3.1 (not the "all" version, because of my protobuf requirement to be 3.20.3)
• protobuf 3.20.3
• pydantic 2.10.6
• quart-schema 0.20.0

Protobuf File Content

// ------------------ Case 1 -----------------------

message Node {
  optional uint64 id = 1;
  optional Node next = 2;
}
message Result {
  optional int32 err_code = 1;
  repeated Node nodes = 2;
}

// -------------------- Case 2 ---------------------
message ListNode {
  optional uint64 id = 1;
  //optional ListNode next = 2;  // <==== Will cause RecursionError
}

message ResultList {
  optional int32 err_code = 1;
  optional ListNode list = 2;
}

// ------------------ Case 3 -----------------------
message TreeChild {
  optional uint64 id = 1;
  repeated TreeNode elt = 2;
}

message TreeNode {
  optional uint64 value = 1;
  optional TreeChild left = 2;
  optional TreeChild right = 3;
}

message ResultTree {
  optional int32 err_code = 1;
  optional TreeNode tree = 2;
}

Use

from quart import Quart
from quart_schema import (
  QuartSchema, RequestSchemaValidationError, 
  validate_querystring, validate_request, validate_response
)
from protobuf_to_pydantic import msg_to_pydantic_model
import master_pb2
from google.protobuf.json_format import MessageToDict

app = Quart(__name__)
QuartSchema(app)

@app.errorhandler(RequestSchemaValidationError)
async def handle_request_validation_error(error):
  return { "errors": str(error.validation_error) }, 400

## Output 1
@app.route('/get')
@validate_response(msg_to_pydantic_model(master_pb2.Result))
async def get():
  msg = master_pb2.Result()
  node = msg.nodes.add()
  node.id = 54
  return MessageToDict(msg, preserving_proto_field_name=True)

## Output 2
@app.route('/get_list')
@validate_response(msg_to_pydantic_model(master_pb2.ResultList))
async def get_list():
  msg = master_pb2.ResultList()
  return MessageToDict(msg, preserving_proto_field_name=True)

## Output 3
@app.route('/get_tree')
@validate_response(msg_to_pydantic_model(master_pb2.ResultTree))
async def get_tree():
  msg = master_pb2.ResultTree()
  child = msg.tree.left
  child.id = 42
  return MessageToDict(msg, preserving_proto_field_name=True)

Output 1

quart_schema.validation.ResponseSchemaValidationError: 1 validation error for Result
nodes.0.next
  Field required [type=missing, input_value={'id': '54'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.10/v/missing

Output 2

  File "site-packages/protobuf_to_pydantic/get_message_option/from_message_option/base.py", line 106, in get_message_option_dict_from_desc
    message_option_dict["nested"][field.message_type.name] = self.get_message_option_dict_from_desc(
  [Previous line repeated 967 more times]
  File "site-packages/protobuf_to_pydantic/get_message_option/from_message_option/base.py", line 100, in get_message_option_dict_from_desc
    field_info_dict = gen_field_info_dict_from_field_desc(type_name, field.full_name, field, self.protobuf_pkg)
  File "site-packages/protobuf_to_pydantic/field_info_rule/protobuf_option_to_field_info/desc.py", line 101, in gen_field_info_dict_from_field_desc
    if isinstance(field, FieldDescriptor):
  File "site-packages/google/protobuf/descriptor.py", line 66, in __instancecheck__
    if super(DescriptorMetaclass, cls).__instancecheck__(obj):
RecursionError: maximum recursion depth exceeded while calling a Python object

Output 3

quart_schema.validation.ResponseSchemaValidationError: `TreeChild` is not fully defined; you should define `TreeNode`, then call `TreeChild.model_rebuild()`.

Expected behavior

• Output 1: { "err_code": 0, "nodes": { "id": 42 } }
• Output 2: { "err_code": 0 }
• Output 3: { "err_code": 0, "tree": { "left": { "id": 42 } } }

Additional context

I have found this issue because of Case 3. While writing a minimal working example for this Github issue I found the Cases 1 and 2. The real world case I am using is closer to Case 3.