AttributeError during deserialization

[sergray]

Hi @SVilgelm

Thank you for implementing propagation of dump mode for #80

I have found the following problem after upgrade during execution of the tests:

AttributeError: 'NoneType' object has no attribute '__propagate_dump_mode__'

Example bellow reproduces it:

from marshmallow import fields
from marshmallow_objects import Model, NestedModel

class Person(Model):
    name = fields.String()
    age = fields.Integer()

class Company(Model):
    name = fields.String()
    owner = NestedModel(Person, allow_none=True)

Company.load({'name': 'ACME', 'owner': None}).dump()

It occurs in

marshmallow_objects/models.py in __propagate_dump_mode__(self, value)
    158         for name, field in self.__schema__.fields.items():
    159             if isinstance(field, fields.Nested):
--> 160                 getattr(self, name).__propagate_dump_mode__(value)
    161 
    162     @contextlib.contextmanager

AttributeError: 'NoneType' object has no attribute '__propagate_dump_mode__'

[SVilgelm]

Fixed in 2.2.1: https://pypi.org/project/marshmallow-objects/2.2.1/

[sergray]

Thanks, @SVilgelm ! 👍