Added a `TypedChoiceField` which acts just like `ChoiceField`, except that it
returns a value coerced by some provided function. Refs #6967. git-svn-id: http://code.djangoproject.com/svn/django/trunk@8771 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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@ -23,6 +23,7 @@ try:
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except NameError:
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from sets import Set as set
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import django.core.exceptions
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from django.utils.translation import ugettext_lazy as _
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from django.utils.encoding import smart_unicode, smart_str
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@ -39,6 +40,7 @@ __all__ = (
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'BooleanField', 'NullBooleanField', 'ChoiceField', 'MultipleChoiceField',
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'ComboField', 'MultiValueField', 'FloatField', 'DecimalField',
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'SplitDateTimeField', 'IPAddressField', 'FilePathField', 'SlugField',
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'TypedChoiceField'
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)
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# These values, if given to to_python(), will trigger the self.required check.
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@ -657,6 +659,33 @@ class ChoiceField(Field):
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return True
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return False
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class TypedChoiceField(ChoiceField):
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def __init__(self, *args, **kwargs):
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self.coerce = kwargs.pop('coerce', lambda val: val)
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self.empty_value = kwargs.pop('empty_value', '')
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super(TypedChoiceField, self).__init__(*args, **kwargs)
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def clean(self, value):
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"""
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Validate that the value is in self.choices and can be coerced to the
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right type.
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"""
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value = super(TypedChoiceField, self).clean(value)
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if value == self.empty_value or value in EMPTY_VALUES:
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return self.empty_value
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# Hack alert: This field is purpose-made to use with Field.to_python as
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# a coercion function so that ModelForms with choices work. However,
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# Django's Field.to_python raises django.core.exceptions.ValidationError,
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# which is a *different* exception than
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# django.forms.utils.ValidationError. So unfortunatly we need to catch
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# both.
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try:
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value = self.coerce(value)
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except (ValueError, TypeError, django.core.exceptions.ValidationError):
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raise ValidationError(self.error_messages['invalid_choice'] % {'value': value})
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return value
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class MultipleChoiceField(ChoiceField):
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hidden_widget = MultipleHiddenInput
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widget = SelectMultiple
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@ -363,6 +363,33 @@ Takes one extra required argument:
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An iterable (e.g., a list or tuple) of 2-tuples to use as choices for this
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field.
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``TypedChoiceField``
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~~~~~~~~~~~~~~~~~~~~
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.. class:: TypedChoiceField(**kwargs)
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Just like a :class:`ChoiceField`, except :class:`TypedChoiceField` takes an
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extra ``coerce`` argument.
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* Default widget: ``Select``
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* Empty value: Whatever you've given as ``empty_value``
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* Normalizes to: the value returned by the ``coerce`` argument.
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* Validates that the given value exists in the list of choices.
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* Error message keys: ``required``, ``invalid_choice``
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Takes extra arguments:
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.. attribute:: TypedChoiceField.coerce
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A function that takes one argument and returns a coerced value. Examples
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include the built-in ``int``, ``float``, ``bool`` and other types. Defaults
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to an identity function.
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.. attribute:: TypedChoiceField.empty_value
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The value to use to represent "empty." Defaults to the empty string;
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``None`` is another common choice here.
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``DateField``
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~~~~~~~~~~~~~
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@ -1077,6 +1077,53 @@ Traceback (most recent call last):
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...
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ValidationError: [u'Select a valid choice. 6 is not one of the available choices.']
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# TypedChoiceField ############################################################
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# TypedChoiceField is just like ChoiceField, except that coerced types will
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# be returned:
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>>> f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int)
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>>> f.clean('1')
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1
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>>> f.clean('2')
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Traceback (most recent call last):
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...
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ValidationError: [u'Select a valid choice. 2 is not one of the available choices.']
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# Different coercion, same validation.
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>>> f.coerce = float
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>>> f.clean('1')
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1.0
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# This can also cause weirdness: be careful (bool(-1) == True, remember)
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>>> f.coerce = bool
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>>> f.clean('-1')
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True
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# Even more weirdness: if you have a valid choice but your coercion function
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# can't coerce, you'll still get a validation error. Don't do this!
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>>> f = TypedChoiceField(choices=[('A', 'A'), ('B', 'B')], coerce=int)
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>>> f.clean('B')
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Traceback (most recent call last):
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...
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ValidationError: [u'Select a valid choice. B is not one of the available choices.']
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# Required fields require values
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>>> f.clean('')
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Traceback (most recent call last):
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...
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ValidationError: [u'This field is required.']
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# Non-required fields aren't required
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>>> f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=False)
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>>> f.clean('')
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''
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# If you want cleaning an empty value to return a different type, tell the field
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>>> f = TypedChoiceField(choices=[(1, "+1"), (-1, "-1")], coerce=int, required=False, empty_value=None)
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>>> print f.clean('')
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None
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# NullBooleanField ############################################################
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>>> f = NullBooleanField()
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