[BUG][PYTHON] Deepcopy fail for allOf schemas

[jtvmatos]

Description

The deepcopy operation fails in models with allof schemas. For example, it is not possible to deepcopy the model dog (from petstore_api.model.dog import Dog). The deepcopy of the Dog model throws a ApiValueError Cannot deserialize input data due to missing discriminator. The discriminator property 'className' is missing at path: ().

openapi-generator version

master

OpenAPI declaration file content or url

Models from openapi-generator/samples/client/petstore/python

Command line used for generation

N/A

Steps to reproduce

>>> from copy import deepcopy
>>> from petstore_api.model.dog import Dog
>>> model_dog = Dog(class_name='Dog', color='white', breed='Jack Russel Terrier')
>>> new_dog = deepcopy(model_dog)

petstore_api.exceptions.ApiValueError: Cannot deserialize input data due to missing discriminator. The discriminator property 'className' is missing at path: ()

Related issues/PRs

may be related with: https://github.com/OpenAPITools/openapi-generator/issues/9669

Suggest a fix/enhancement

In model_utils.py file (from methods_shared.mustache mustache) add the **self.__dict__ *args to the __new__ function (as in the copy function) seems to solve the problem:

    def __deepcopy__(self, memo):
        cls = self.__class__

        if self.get("_spec_property_naming", False):
            new_inst = cls._new_from_openapi_data()
        else:
            new_inst = cls.__new__(cls, **self.__dict__)

        for k, v in self.__dict__.items():
            setattr(new_inst, k, deepcopy(v, memo))
        return new_inst