django-model-utils/model_utils/__init__.py
2010-04-16 00:37:12 -04:00

95 lines
3 KiB
Python

class ChoiceEnum(object):
"""
DEPRECATED: Use ``Choices`` (below) instead. This class has less
flexibility for human-readable display, and greater potential for
surprising data corruption if new choices are inserted in the
middle of the list. Automatic assignment of numeric IDs is not
such a great idea after all.
A class to encapsulate handy functionality for lists of choices
for a Django model field.
Accepts verbose choice names as arguments, and automatically
assigns numeric keys to them. When iterated over, behaves as the
standard Django choices list of two-tuples.
Attribute access allows conversion of verbose choice name to
choice key, dictionary access the reverse.
Example:
>>> STATUS = ChoiceEnum('DRAFT', 'PUBLISHED')
>>> STATUS.DRAFT
0
>>> STATUS[1]
'PUBLISHED'
>>> tuple(STATUS)
((0, 'DRAFT'), (1, 'PUBLISHED'))
"""
def __init__(self, *choices):
import warnings
warnings.warn("ChoiceEnum is deprecated, use Choices instead.",
PendingDeprecationWarning)
self._choices = tuple(enumerate(choices))
self._choice_dict = dict(self._choices)
self._reverse_dict = dict(((i[1], i[0]) for i in self._choices))
def __iter__(self):
return iter(self._choices)
def __getattr__(self, attname):
try:
return self._reverse_dict[attname]
except KeyError:
raise AttributeError(attname)
def __getitem__(self, key):
return self._choice_dict[key]
def __repr__(self):
return '%s(%s)' % (self.__class__.__name__,
', '.join(("'%s'" % i[1] for i in self._choices)))
class Choices(object):
"""
A class to encapsulate handy functionality for lists of choices
for a Django model field.
Accepts as arguments either tuples mapping choice IDs (strings) to
human-readable names, or simply choice IDs (in which case the ID
is also used as the human-readable name). When iterated over,
behaves as the standard Django choices list of two-tuples.
Choice IDs can be accessed as attributes for readable code.
"""
def __init__(self, *choices):
self._choices = list(self.equalize(choices))
self._choice_dict = dict(self._choices)
self._reverse_dict = dict(((i[0], i[0]) for i in self._choices))
def equalize(self, choices):
for choice in choices:
if isinstance(choice, (list, tuple)):
yield choice
else:
yield (choice, choice)
def __iter__(self):
return iter(self._choices)
def __getattr__(self, attname):
try:
return self._reverse_dict[attname]
except KeyError:
raise AttributeError(attname)
def __getitem__(self, index):
return self._choices[index]
def __repr__(self):
return '%s(%s)' % (self.__class__.__name__,
', '.join(("'%s'" % i[0] for i in self._choices)))