from typing import Tuple
from django.db import models
from django.utils.translation import gettext_lazy as _
from eav.logic.managers import EnumValueManager
from eav.logic.object_pk import get_pk_format
from eav.logic.slug import SLUGFIELD_MAX_LENGTH
[docs]class EnumValue(models.Model):
"""
*EnumValue* objects are the value 'choices' to multiple choice *TYPE_ENUM*
:class:`Attribute` objects. They have only one field, *value*, a
``CharField`` that must be unique.
For example::
yes = EnumValue.objects.create(value='Yes') # doctest: SKIP
no = EnumValue.objects.create(value='No')
unknown = EnumValue.objects.create(value='Unknown')
ynu = EnumGroup.objects.create(name='Yes / No / Unknown')
ynu.values.add(yes, no, unknown)
Attribute.objects.create(name='has fever?',
datatype=Attribute.TYPE_ENUM, enum_group=ynu)
# = <Attribute: has fever? (Multiple Choice)>
.. note::
The same *EnumValue* objects should be reused within multiple
*EnumGroups*. For example, if you have one *EnumGroup* called: *Yes /
No / Unknown* and another called *Yes / No / Not applicable*, you should
only have a total of four *EnumValues* objects, as you should have used
the same *Yes* and *No* *EnumValues* for both *EnumGroups*.
"""
objects = EnumValueManager()
class Meta:
verbose_name = _('EnumValue')
verbose_name_plural = _('EnumValues')
id = get_pk_format()
value = models.CharField(
_('Value'),
db_index=True,
unique=True,
max_length=SLUGFIELD_MAX_LENGTH,
)
def __str__(self) -> str:
"""String representation of `EnumValue` instance."""
return str(
self.value,
)
def __repr__(self) -> str:
"""String representation of `EnumValue` object."""
return f'<EnumValue {self.value}>'
[docs] def natural_key(self) -> Tuple[str]:
"""
Retrieve the natural key for the EnumValue instance.
The natural key for an EnumValue is defined by its `value`. This method returns
the value of the instance as a single-element tuple.
Returns
-------
tuple: A tuple containing the value of the EnumValue instance.
"""
return (self.value,)
