import enum 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): 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) cls._value2label_map_ = dict(zip(cls._value2member_map_, labels)) # Add a label property to instances of enum which uses the enum member # that is passed in as "self" as the value to use when looking up the # label in the choices. cls.label = property(lambda self: cls._value2label_map_.get(self.value)) cls.do_not_call_in_templates = True return enum.unique(cls) def __contains__(cls, member): if not isinstance(member, enum.Enum): # Allow non-enums to match against member values. return member in {x.value 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.""" 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) 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