Enum for use with Django ChoiceField

choices_enum.py

from enum import Enum, EnumMeta


class ChoicesEnumMeta(EnumMeta):
    def __iter__(self):
        return ((choice.name, choice.value) for choice in super().__iter__())


class ChoicesEnum(Enum, metaclass=ChoicesEnumMeta):
    def __str__(self):
        return self.name


"""
Enum for Django ChoiceField use.

Usage:

    class Colors(ChoicesEnum):
        red = "Red"
        green = "Green"
        blue = "Blue"

    class Car(models.Model):
        color = models.CharField(max_length=20, choices=Colors)

red_cars = Car.objects.filter(color=Colors.RED)
"""

Do you not get this error in Admin when editing?

  File "/Users/ryan/Documents/asdf/django/lib/python3.6/site-packages/django/forms/widgets.py", line 677, in get_context
    context = super().get_context(name, value, attrs)
  File "/Users/ryan/Documents/asdf/django/lib/python3.6/site-packages/django/forms/widgets.py", line 637, in get_context
    context['widget']['optgroups'] = self.optgroups(name, context['widget']['value'], attrs)
  File "/Users/ryan/Documents/asdf/django/lib/python3.6/site-packages/django/forms/widgets.py", line 585, in optgroups
    for index, (option_value, option_label) in enumerate(self.choices):
  File "/Users/ryan/Documents/asdf/django/lib/python3.6/site-packages/django/forms/fields.py", line 747, in __iter__
    yield from self.choices_func()
TypeError: __call__() missing 1 required positional argument: 'value'

@nitrag I've just tried and I'm not having any issue. In my current implementation I nested the ChoicesEnum class inside the model class:

class Order(models.Model):

    class Status(ChoicesEnum):
        DRAFT = 'Draft'
        CONFIRMED = 'Confirmed'
        PROCESSED = 'Processed'
        CANCELED = 'Canceled'

    status = models.CharField(max_length=16, choices=Status, default=Status.DRAFT, verbose_name='status')

After that I'm being able of doing:

Order.objects.filter(status=Order.Status.DRAFT).count()

The only two issues I faced were:

1. I have to manually edit the migration and fix the default from oakfrog.orders.models.Status('Draft') to oakfrog.orders.models.Order.Status('Draft') (It seems that Django are not handling well the nested Class when doing the migration).
2. When testing a DRF serializer I needed to str() the option to make it assert: self.assertEqual(data['status'], str(Order.Status.CONFIRMED)). I suspect it's due DRAFT in the Enum is a symbolic name and the serializer is casting it to a plain string.

I hope it helps!