Choices Enum

Python's Enum with extra powers to play nice with labels and choices fields.

• Free software: BSD license
• Documentation: https://python-choicesenum.readthedocs.io.

Installation

Install choicesenum using pip:

$ pip install choicesenum

Features

• An ChoicesEnum that can be used to create constant groups.
• ChoicesEnum can define labels to be used in choices fields.
• Django fields included: EnumCharField and EnumIntegerField.
• Support (tested) for Python 2.7, 3.4, 3.5 and 3.6.
• Support (tested) for Django 1.6.1 (with south), 1.7, 1.8, 1.9, 1.10 and 1.11.

Usage examples

Example with HttpStatuses:

class HttpStatuses(ChoicesEnum):
    OK = 200
    BAD_REQUEST = 400
    UNAUTHORIZED = 401
    FORBIDDEN = 403

All Enum types can be compared against their values:

assert HttpStatuses.OK == 200
assert HttpStatuses.BAD_REQUEST == 400
assert HttpStatuses.UNAUTHORIZED == 401
assert HttpStatuses.FORBIDDEN == 403

status_code = HttpStatuses.OK
assert 200 <= status_code <= 300

All Enum types have by default a display derived from the enum identifier:

assert HttpStatuses.OK.display == 'Ok'
assert HttpStatuses.BAD_REQUEST.display == 'Bad request'
assert HttpStatuses.UNAUTHORIZED.display == 'Unauthorized'
assert HttpStatuses.FORBIDDEN.display == 'Forbidden'

You can easily define your own custom display for an Enum item using a tuple:

class HttpStatuses(ChoicesEnum):
    OK = 200, 'Everything is fine'
    BAD_REQUEST = 400, 'You did a mistake'
    UNAUTHORIZED = 401, 'I know your IP'
    FORBIDDEN = 403

assert HttpStatuses.OK.display == 'Everything is fine'
assert HttpStatuses.BAD_REQUEST.display == 'You did a mistake'
assert HttpStatuses.UNAUTHORIZED.display == 'I know your IP'
assert HttpStatuses.FORBIDDEN.display == 'Forbidden'

You can declare custom properties and methods:

class HttpStatuses(ChoicesEnum):
    OK = 200, 'Everything is fine'
    BAD_REQUEST = 400, 'You did a mistake'
    UNAUTHORIZED = 401, 'I know your IP'
    FORBIDDEN = 403

    @property
    def is_error(self):
        return self >= self.BAD_REQUEST

assert HttpStatuses.OK.is_error is False
assert HttpStatuses.BAD_REQUEST.is_error is True
assert HttpStatuses.UNAUTHORIZED.is_error is True

Example with Colors:

from choicesenum import ChoicesEnum

class Colors(ChoicesEnum):
    # For fixed order in  py2.7, py3.4+ are ordered by default
    _order_ = 'RED GREEN BLUE'

    RED = '#f00', 'Vermelho'
    GREEN = '#0f0', 'Verde'
    BLUE = '#00f', 'Azul'

assert Colors.RED == '#f00'
assert Colors.GREEN == '#0f0'
assert Colors.BLUE == '#00f'

assert Colors.RED.display == 'Vermelho'
assert Colors.GREEN.display == 'Verde'
assert Colors.BLUE.display == 'Azul'

Use .choices() method to receive a list of tuples (item, display):

# choices
assert list(Colors.choices()) == [
    ('#f00', 'Vermelho'),
    ('#0f0', 'Verde'),
    ('#00f', 'Azul'),
]

For each enum item, a dynamic property is_<enum_item> is generated to allow quick boolean checks:

color = Colors.RED
assert color.is_red
assert not color.is_blue
assert not color.is_green

if color.is_red:
    print 'Is red!'

The enum item can be used whenever the value is needed:

assert u'Currrent color is {c} ({c.display})'.format(c=color) ==\
       u'Currrent color is #f00 (Vermelho)'

Usage with the custom Django fields:

from django.db import models
from choicesenum.django.fields import EnumCharField

class ColorModel(models.Model):
    color = EnumCharField(
        max_length=100,
        enum=Colors,
        default=Colors.GREEN,
    )

instance = ColorModel()
assert instance.color ==  Colors.GREEN
assert instance.color.is_green is True
assert instance.color.value == Colors.GREEN.value == '#0f0'
assert instance.color.display == Colors.GREEN.display

instance.color = '#f00'
assert instance.color == '#f00'
assert instance.color.value == '#f00'
assert instance.color.display == 'Vermelho'

Is guaranteed that the field value is always a ChoicesEnum item. Pay attention that the field will only accept valid values for the Enum in use, so if your field allow null, your enum should also:

from django.db import models
from choicesenum import ChoicesEnum
from choicesenum.django.fields import EnumIntegerField

class UserStatus(ChoicesEnum):
    UNDEFINED = None
    PENDING = 1
    ACTIVE = 2
    INACTIVE = 3
    DELETED = 4


class User(models.Model):
    status = EnumIntegerField(enum=UserStatus, null=True, )

instance = User()
assert instance.status.is_undefined is True
assert instance.status.value is None
assert instance.status == UserStatus.UNDEFINED
assert instance.status.display == 'Undefined'

# again...
instance.status = None
assert instance.status.is_undefined is True

Usage with Graphene Enums:

UserStatusEnum = graphene.Enum.from_enum(UserStatus)