import enum
from types import DynamicClassAttribute
from django.utils.functional import Promise
__all__ = ["Choices", "IntegerChoices", "TextChoices"]
class ChoicesMeta(enum.EnumMeta):
"""A metaclass for creating a enum choices."""
def __new__(metacls, classname, bases, classdict, **kwds):
labels = []
for key in classdict._member_names:
value = classdict[key]
if (
isinstance(value, (list, tuple))
and len(value) > 1
and isinstance(value[-1], (Promise, str))
):
*value, label = value
value = tuple(value)
else:
label = key.replace("_", " ").title()
labels.append(label)
# Use dict.__setitem__() to suppress defenses against double
# assignment in enum's classdict.
dict.__setitem__(classdict, key, value)
cls = super().__new__(metacls, classname, bases, classdict, **kwds)
for member, label in zip(cls.__members__.values(), labels):
member._label_ = label
return enum.unique(cls)
def __contains__(cls, member):
if not isinstance(member, enum.Enum):
# Allow non-enums to match against member values.
return any(x.value == member for x in cls)
return super().__contains__(member)
@property
def names(cls):
empty = ["__empty__"] if hasattr(cls, "__empty__") else []
return empty + [member.name for member in cls]
@property
def choices(cls):
empty = [(None, cls.__empty__)] if hasattr(cls, "__empty__") else []
return empty + [(member.value, member.label) for member in cls]
@property
def labels(cls):
return [label for _, label in cls.choices]
@property
def values(cls):
return [value for value, _ in cls.choices]
class Choices(enum.Enum, metaclass=ChoicesMeta):
"""Class for creating enumerated choices."""
@DynamicClassAttribute
def label(self):
return self._label_
@property
def do_not_call_in_templates(self):
return True
def __str__(self):
"""
Use value when cast to str, so that Choices set as model instance
attributes are rendered as expected in templates and similar contexts.
"""
return str(self.value)
# A similar format was proposed for Python 3.10.
def __repr__(self):
return f"{self.__class__.__qualname__}.{self._name_}"
class IntegerChoices(int, Choices):
"""Class for creating enumerated integer choices."""
pass
class TextChoices(str, Choices):
"""Class for creating enumerated string choices."""
def _generate_next_value_(name, start, count, last_values):
return name