Recursive model error in latest version

[DenSinH]

It seems something broke between releases 2.12.1 and 2.13.0, which has not been fixed yet, regarding cyclic / self referential models. The following minimal example 'builds' in release 2.12.1 and fails in 2.13.0, 2.13.1 and 2.14.0:

from pydantic_xml import BaseXmlModel, element


class MyBaseClass(BaseXmlModel):
    name: str = element("Name")
    children: list['MyDerivedClass'] = element(tag="Derived", default_factory=list)


class MyDerivedClass(MyBaseClass, tag="Derived"):
    field: int = element("type")

Stack trace:

Traceback (most recent call last):
  File "C:\projects\playground\stuff.py", line 9, in <module>
    class MyDerivedClass(MyBaseClass, tag="Derived"):
  File "C:\projects\playground\venv\Lib\site-packages\pydantic_xml\model.py", line 373, in __new__
    cls = typing.cast(Type['BaseXmlModel'], super().__new__(mcls, name, bases, namespace, **kwargs))
                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_model_construction.py", line 137, in __new__
    cls: type[BaseModel] = super().__new__(mcs, cls_name, bases, namespace, **kwargs)  # type: ignore
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen abc>", line 106, in __new__
  File "C:\projects\playground\venv\Lib\site-packages\pydantic_xml\model.py", line 433, in __init_subclass__
    if func := getattr(cls, attr_name, None):
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_mock_val_ser.py", line 43, in __len__
    return self._get_built().__len__()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_mock_val_ser.py", line 43, in __len__
    return self._get_built().__len__()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_mock_val_ser.py", line 43, in __len__
    return self._get_built().__len__()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  [Previous line repeated 965 more times]
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_mock_val_ser.py", line 53, in _get_built
    schema = self._attempt_rebuild()
             ^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_mock_val_ser.py", line 126, in handler
    if cls.model_rebuild(raise_errors=False, _parent_namespace_depth=5) is not False:
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic_xml\model.py", line 482, in model_rebuild
    super().model_rebuild(**kwargs)
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\main.py", line 563, in model_rebuild
    return _model_construction.complete_model_class(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_model_construction.py", line 577, in complete_model_class
    schema = cls.__get_pydantic_core_schema__(cls, handler)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\main.py", line 671, in __get_pydantic_core_schema__
    return handler(source)
           ^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_schema_generation_shared.py", line 83, in __call__
    schema = self._handler(source_type)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 655, in generate_schema
    schema = self._generate_schema_inner(obj)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 924, in _generate_schema_inner
    return self._model_schema(obj)
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 739, in _model_schema
    {k: self._generate_md_field_schema(k, v, decorators) for k, v in fields.items()},
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 1115, in _generate_md_field_schema
    common_field = self._common_field_schema(name, field_info, decorators)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 1308, in _common_field_schema
    schema = self._apply_annotations(
             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 2107, in _apply_annotations
    schema = get_inner_schema(source_type)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_schema_generation_shared.py", line 83, in __call__
    schema = self._handler(source_type)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 2088, in inner_handler
    schema = self._generate_schema_inner(obj)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 929, in _generate_schema_inner
    return self.match_type(obj)
           ^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 1029, in match_type
    return self._match_generic_type(obj, origin)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 1062, in _match_generic_type
    return self._list_schema(self._get_first_arg_or_any(obj))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 431, in _list_schema
    return core_schema.list_schema(self.generate_schema(items_type))
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 655, in generate_schema
    schema = self._generate_schema_inner(obj)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 918, in _generate_schema_inner
    return self.generate_schema(self._resolve_forward_ref(obj))
                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 864, in _resolve_forward_ref
    obj = _typing_extra.eval_type_backport(obj, globalns=self._types_namespace)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_typing_extra.py", line 279, in eval_type_backport
    return _eval_type_backport(value, globalns, localns, type_params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_typing_extra.py", line 303, in _eval_type_backport
    return _eval_type(value, globalns, localns, type_params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\projects\playground\venv\Lib\site-packages\pydantic\_internal\_typing_extra.py", line 332, in _eval_type
    return typing._eval_type(  # type: ignore
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\programs\python\Lib\typing.py", line 415, in _eval_type
    return t._evaluate(globalns, localns, type_params, recursive_guard=recursive_guard)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\programs\python\Lib\typing.py", line 947, in _evaluate
    eval(self.__forward_code__, globalns, localns),
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
RecursionError: maximum recursion depth exceeded

I was really hoping to use the (temporary) fix for CDATA fields from #201, but sadly I can't because of this issue.

[dapper91]

fixed in version 2.14.1