Added a `TypedChoiceField` which acts just like `ChoiceField`, except that it (4ae746b5) · Commits · Dom Sekotill / django

django/forms/fields.py

+29 −0

Original line number	Diff line number	Diff line
		@@ -23,6 +23,7 @@ try:
		except NameError:
		from sets import Set as set

		import django.core.exceptions
		from django.utils.translation import ugettext_lazy as _
		from django.utils.encoding import smart_unicode, smart_str

		@@ -39,6 +40,7 @@ __all__ = (
		'BooleanField', 'NullBooleanField', 'ChoiceField', 'MultipleChoiceField',
		'ComboField', 'MultiValueField', 'FloatField', 'DecimalField',
		'SplitDateTimeField', 'IPAddressField', 'FilePathField', 'SlugField',
		'TypedChoiceField'
		)

		# These values, if given to to_python(), will trigger the self.required check.
		@@ -657,6 +659,33 @@ class ChoiceField(Field):
		return True
		return False

		class TypedChoiceField(ChoiceField):
		def __init__(self, args, *kwargs):
		self.coerce = kwargs.pop('coerce', lambda val: val)
		self.empty_value = kwargs.pop('empty_value', '')
		super(TypedChoiceField, self).__init__(args, *kwargs)

		def clean(self, value):
		"""
		Validate that the value is in self.choices and can be coerced to the
		right type.
		"""
		value = super(TypedChoiceField, self).clean(value)
		if value == self.empty_value or value in EMPTY_VALUES:
		return self.empty_value

		# Hack alert: This field is purpose-made to use with Field.to_python as
		# a coercion function so that ModelForms with choices work. However,
		# Django's Field.to_python raises django.core.exceptions.ValidationError,
		# which is a different exception than
		# django.forms.utils.ValidationError. So unfortunatly we need to catch
		# both.
		try:
		value = self.coerce(value)
		except (ValueError, TypeError, django.core.exceptions.ValidationError):
		raise ValidationError(self.error_messages['invalid_choice'] % {'value': value})
		return value

		class MultipleChoiceField(ChoiceField):
		hidden_widget = MultipleHiddenInput
		widget = SelectMultiple

docs/ref/forms/fields.txt

+27 −0

Original line number	Diff line number	Diff line
		@@ -363,6 +363,33 @@ Takes one extra required argument:
		An iterable (e.g., a list or tuple) of 2-tuples to use as choices for this
		field.

		``TypedChoiceField``
		~~~~~~~~~~~~~~~~~~~~

		.. class:: TypedChoiceField(**kwargs)

		Just like a :class:`ChoiceField`, except :class:`TypedChoiceField` takes an
		extra ``coerce`` argument.

		* Default widget: ``Select``
		* Empty value: Whatever you've given as ``empty_value``
		* Normalizes to: the value returned by the ``coerce`` argument.
		* Validates that the given value exists in the list of choices.
		* Error message keys: ``required``, ``invalid_choice``

		Takes extra arguments:

		.. attribute:: TypedChoiceField.coerce

		A function that takes one argument and returns a coerced value. Examples
		include the built-in ``int``, ``float``, ``bool`` and other types. Defaults
		to an identity function.

		.. attribute:: TypedChoiceField.empty_value

		The value to use to represent "empty." Defaults to the empty string;
		``None`` is another common choice here.

		``DateField``
		~~~~~~~~~~~~~

tests/regressiontests/forms/fields.py

+47 −0

Original line number	Diff line number	Diff line
		@@ -1077,6 +1077,53 @@ Traceback (most recent call last):
		...
		ValidationError: [u'Select a valid choice. 6 is not one of the available choices.']

		# TypedChoiceField ############################################################

		# TypedChoiceField is just like ChoiceField, except that coerced types will
		# be returned:
		>>> f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int)
		>>> f.clean('1')
		1
		>>> f.clean('2')
		Traceback (most recent call last):
		...
		ValidationError: [u'Select a valid choice. 2 is not one of the available choices.']

		# Different coercion, same validation.
		>>> f.coerce = float
		>>> f.clean('1')
		1.0


		# This can also cause weirdness: be careful (bool(-1) == True, remember)
		>>> f.coerce = bool
		>>> f.clean('-1')
		True

		# Even more weirdness: if you have a valid choice but your coercion function
		# can't coerce, you'll still get a validation error. Don't do this!
		>>> f = TypedChoiceField(choices=[('A', 'A'), ('B', 'B')], coerce=int)
		>>> f.clean('B')
		Traceback (most recent call last):
		...
		ValidationError: [u'Select a valid choice. B is not one of the available choices.']

		# Required fields require values
		>>> f.clean('')
		Traceback (most recent call last):
		...
		ValidationError: [u'This field is required.']

		# Non-required fields aren't required
		>>> f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=False)
		>>> f.clean('')
		''

		# If you want cleaning an empty value to return a different type, tell the field
		>>> f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=False, empty_value=None)
		>>> print f.clean('')
		None

		# NullBooleanField ############################################################

		>>> f = NullBooleanField()