django-enumfield 3.0

Custom Django field for using enumerations of named constants

django-enumfield

Provides an enumeration Django model field (using IntegerField) with reusable enums and transition validation.

Installation

Currently, we test Django versions 2.2-4.0 and Python versions 3.7-3.10.

Install django-enumfield in your Python environment:

$ pip install django-enumfield

Upgrading from django-enumfield 1.x? See the migration guide

For use with Django versions prior to 1.8 use version 1.2.1

For use with Django versions prior to 1.11 use version 1.5

Usage

Create an Enum-class and pass it as first argument to the Django model EnumField.

from django.db import models
from django_enumfield import enum


class BeerStyle(enum.Enum):
    LAGER = 0
    STOUT = 1
    WEISSBIER = 2


class Beer(models.Model):
    style = enum.EnumField(BeerStyle, default=BeerStyle.LAGER)


# Use .get to get enum values from either name or ints
print(BeerStyle.get("LAGER"))  # <BeerStyle.LAGER: 0>
print(BeerStyle.get(1))  # <BeerStyle.STOUT: 1>
print(BeerStyle.get(BeerStyle.WEISSBIER))  # <BeerStyle.WEISSBIER: 2>

# It's also possible to use the normal enum way to get the value
print(BeerStyle(1))  # <BeerStyle.STOUT: 1>
print(BeerStyle["LAGER"])  # <BeerStyle.LAGER: 0>

# The enum value has easy access to their value and name
print(BeerStyle.LAGER.value)  # 0
print(BeerStyle.LAGER.name)  # "LAGER"

For more information about Python 3 enums (which our Enum inherits, IntEnum to be specific) checkout the docs.

Setting the default value

You can also set default value on your enum class using __default__ attribute

from django.db import models
from django_enumfield import enum


class BeerStyle(enum.Enum):
    LAGER = 0
    STOUT = 1
    WEISSBIER = 2

    __default__ = LAGER


class BeerStyleNoDefault(enum.Enum):
    LAGER = 0


class Beer(models.Model):
    style_default_lager = enum.EnumField(BeerStyle)
    style_default_stout = enum.EnumField(BeerStyle, default=BeerStyle.STOUT)
    style_default_null = enum.EnumField(BeerStyleNoDefault, null=True, blank=True)


# When you set __default__ attribute, you can access default value via
# `.default()` method of your enum class
assert BeerStyle.default() == BeerStyle.LAGER

beer = Beer.objects.create()
assert beer.style_default_larger == BeerStyle.LAGER
assert beer.style_default_stout == BeerStyle.STOUT
assert beer.style_default_null is None

Labels

You can use your own labels for Enum items

from django.utils.translation import gettext_lazy
from django_enumfield import enum


class Animals(enum.Enum):
    CAT = 1
    DOG = 2
    SHARK = 3

    __labels__ = {
        CAT: gettext_lazy("Cat"),
        DOG: gettext_lazy("Dog"),
    }


print(Animals.CAT.label)  # "Cat"
print(Animals.SHARK.label)  # "SHARK"

# There's also classmethods for getting the label
print(Animals.get_label(2))  # "Dog"
print(Animals.get_label("DOG"))  # "Dog"

Validate transitions

The Enum-class provides the possibility to use transition validation.

from django.db import models
from django_enumfield import enum
from django_enumfield.exceptions import InvalidStatusOperationError


class PersonStatus(enum.Enum):
    ALIVE = 1
    DEAD = 2
    REANIMATED = 3

    __transitions__ = {
        DEAD: (ALIVE,),  # Can go from ALIVE to DEAD
        REANIMATED: (DEAD,)  # Can go from DEAD to REANIMATED
    }


class Person(models.Model):
    status = enum.EnumField(PersonStatus)

# These transitions state that a PersonStatus can only go to DEAD from ALIVE and to REANIMATED from DEAD.
person = Person.objects.create(status=PersonStatus.ALIVE)
try:
    person.status = PersonStatus.REANIMATED
except InvalidStatusOperationError:
    print("Person status can not go from ALIVE to REANIMATED")
else:
    # All good
    person.save()

In forms

The Enum-class can also be used without the EnumField. This is very useful in Django form ChoiceFields.

from django import forms
from django_enumfield import enum
from django_enumfield.forms.fields import EnumChoiceField


class GenderEnum(enum.Enum):
    MALE = 1
    FEMALE = 2

    __labels__ = {
        MALE: "Male",
        FEMALE: "Female",
    }


class PersonForm(forms.Form):
    gender = EnumChoiceField(GenderEnum)

Rendering PersonForm in a template will generate a select-box with "Male" and "Female" as option labels for the gender field.

Local Development Environment

Make sure black and isort is installed in your env with pip install -e .[dev].

Before committing run make format to apply black and isort to all files.