Allow setting None to NestedModel field

Hi,

I’m setting up my models like this

from fireo import models
class NestedModel(models.Model):
     a = models.TextField()

class TestingTheModel(models.Model):
     nested = models.NestedModel(NestedModel, required=False, default=None)
     b = models.TextField()
     class Meta:
             ignore_none_field = True

and then saving the model:

TestingTheModel(nested=None, b='xd').save()

The Firestore document after this operation:

{
   "nested": {},
   "b": "xd"
}

I would like to get this data in Firestore:

{
   "nested": None,
   "b": "xd"
}

Any tips on how this could be achieved?

I am more than happy to have any solution to his problem: adding parameters, CustomField, extending NestedModel etc. works for me.

[monthero]

I wrote this “flexible” NestedModelField that has been working quite well for me, allows for repeated nested model as well. Saves things as None, Dict or List[Dict]

class FlexibleNestedModelField(Field):
    allowed_attributes = ["repeated"]
    repeated: bool = False
    required: bool = False

    def __init__(self, model, *args, **kwargs):
        if "required" not in kwargs:
            kwargs["required"] = False

        if 'repeated' not in kwargs:
            kwargs['repeated'] = False

        self.required = kwargs['required']
        super().__init__(*args, **kwargs)
        self.repeated = kwargs['repeated']
        # Check nested model class is subclass for Model
        from fireo.models import Model

        if not issubclass(model, Model):
            raise NestedModelTypeError(
                f'Nested model "{model.__name__}" must be inherit from Model '
                f'class')
        self.nested_model = model

    def attr_repeated(self, attr_val, field_val):
        """Method for attribute auto_add"""
        if attr_val:
            if not field_val:
                return []
            if field_val and not isinstance(field_val, list):
                return [field_val]
        return field_val

    def db_value(self, val):
        if isinstance(val, list) and not self.repeated:
            raise ValueError(
                "Got list but 'repeated' is set to False"
            )

        if val is None and self.required:
            if self.repeated:
                return []
            else:
                raise ValueError(
                    "Value cannot be empty when 'required' is True"
                )

        if val:
            return (
                [entry.to_dict() for entry in val]
                if isinstance(val, list)
                else val.to_dict()
            )

        return val

[AxeemHaider]

@monthero Thanks for your effort for creating this FlexibleNestedModelField it will be great if you send a PR for this I will merge it. Name it properly instead of FlexibleNestedModelField and if you can write docs for how to use it will be helpful for other.

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