I’m working on a custom field that is just a shortcut to ForeignKey
that points to addresses.Country
model.
When I run makemigrations
it returns this error with I’m not sure:
TypeError: Couldn't reconstruct field rsft_country on properties.Property: django.db.models.fields.related.ForeignKey.__init__() got multiple values for keyword argument 'to'
I understand that there are two to
arguments passed but I don’t understand why. It looks like the field is initialized two times. Once with the kwargs
I provided and then with all the kwargs.
class RsftCountryField(models.ForeignKey): def __init__(self, verbose_name=None, **kwargs): print(kwargs) kwargs['verbose_name'] = verbose_name or 'Krajina' to = 'addresses.Country' on_delete = kwargs.pop('on_delete',None) or models.PROTECT related_name = kwargs.pop('related_name',None) or '+' super().__init__(to, on_delete, related_name=related_name, related_query_name=None, limit_choices_to=None, parent_link=False, to_field=None, db_constraint=True, **kwargs)
Model:
... rsft_country = addresses_fields.RsftCountryField(null=True, blank=True)
It prints kwargs
two times:
{'null': True, 'blank': True} {'blank': True, 'null': True, 'related_name': '+', 'on_delete': <function PROTECT at 0x7fa9fa277d00>, 'to': 'addresses.country'}
Why does it do that and how to make it work?
EDIT:
Basically, I just want to provide all the fields by default without having to specify it everytime I define the country
field in model.
Advertisement
Answer
The problem is the .deconstruct()
method [Django-doc], since that will :
class RsftCountryField(models.ForeignKey): def __init__(self, verbose_name=None, **kwargs): kwargs['verbose_name'] = verbose_name or 'Krajina' to = 'addresses.Country' on_delete = kwargs.pop('on_delete',None) or models.PROTECT related_name = kwargs.pop('related_name', None) or '+' super().__init__( to, on_delete, related_name=related_name, related_query_name=None, limit_choices_to=None, parent_link=False, to_field=None, db_constraint=True, **kwargs ) def deconstruct(self): name, path, args, kwargs = super().deconstruct() kwargs.pop('to', None) kwargs.pop('related_query_name', None) kwargs.pop('limit_choices_to', None) kwargs.pop('parent_link', None) kwargs.pop('to_field', None) kwargs.pop('db_constraint', None) return name, path, args, kwargs
You will need to make new migrations where a RsftCountryField
is involved.