822 lines
27 KiB
Plaintext
822 lines
27 KiB
Plaintext
.. _ref-forms-fields:
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===========
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Form fields
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===========
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.. module:: django.forms.fields
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:synopsis: Django's built-in form fields.
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.. currentmodule:: django.forms
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.. class:: Field(**kwargs)
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When you create a ``Form`` class, the most important part is defining the
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fields of the form. Each field has custom validation logic, along with a few
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other hooks.
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.. method:: Field.clean(value)
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Although the primary way you'll use ``Field`` classes is in ``Form`` classes,
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you can also instantiate them and use them directly to get a better idea of
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how they work. Each ``Field`` instance has a ``clean()`` method, which takes
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a single argument and either raises a ``django.forms.ValidationError``
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exception or returns the clean value::
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>>> from django import forms
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>>> f = forms.EmailField()
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>>> f.clean('foo@example.com')
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u'foo@example.com'
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>>> f.clean(u'foo@example.com')
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u'foo@example.com'
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>>> f.clean('invalid e-mail address')
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Traceback (most recent call last):
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...
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ValidationError: [u'Enter a valid e-mail address.']
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Core field arguments
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--------------------
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Each ``Field`` class constructor takes at least these arguments. Some
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``Field`` classes take additional, field-specific arguments, but the following
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should *always* be accepted:
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``required``
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~~~~~~~~~~~~
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.. attribute:: Field.required
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By default, each ``Field`` class assumes the value is required, so if you pass
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an empty value -- either ``None`` or the empty string (``""``) -- then
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``clean()`` will raise a ``ValidationError`` exception::
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>>> f = forms.CharField()
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>>> f.clean('foo')
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u'foo'
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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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>>> f.clean(None)
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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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>>> f.clean(' ')
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u' '
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>>> f.clean(0)
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u'0'
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>>> f.clean(True)
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u'True'
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>>> f.clean(False)
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u'False'
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To specify that a field is *not* required, pass ``required=False`` to the
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``Field`` constructor::
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>>> f = forms.CharField(required=False)
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>>> f.clean('foo')
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u'foo'
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>>> f.clean('')
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u''
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>>> f.clean(None)
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u''
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>>> f.clean(0)
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u'0'
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>>> f.clean(True)
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u'True'
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>>> f.clean(False)
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u'False'
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If a ``Field`` has ``required=False`` and you pass ``clean()`` an empty value,
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then ``clean()`` will return a *normalized* empty value rather than raising
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``ValidationError``. For ``CharField``, this will be a Unicode empty string.
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For other ``Field`` classes, it might be ``None``. (This varies from field to
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field.)
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``label``
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~~~~~~~~~
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.. attribute:: Field.label
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The ``label`` argument lets you specify the "human-friendly" label for this
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field. This is used when the ``Field`` is displayed in a ``Form``.
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As explained in "Outputting forms as HTML" above, the default label for a
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``Field`` is generated from the field name by converting all underscores to
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spaces and upper-casing the first letter. Specify ``label`` if that default
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behavior doesn't result in an adequate label.
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Here's a full example ``Form`` that implements ``label`` for two of its fields.
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We've specified ``auto_id=False`` to simplify the output::
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>>> class CommentForm(forms.Form):
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... name = forms.CharField(label='Your name')
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... url = forms.URLField(label='Your Web site', required=False)
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... comment = forms.CharField()
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>>> f = CommentForm(auto_id=False)
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>>> print f
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<tr><th>Your name:</th><td><input type="text" name="name" /></td></tr>
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<tr><th>Your Web site:</th><td><input type="text" name="url" /></td></tr>
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<tr><th>Comment:</th><td><input type="text" name="comment" /></td></tr>
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``initial``
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~~~~~~~~~~~
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.. attribute:: Field.initial
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The ``initial`` argument lets you specify the initial value to use when
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rendering this ``Field`` in an unbound ``Form``.
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To specify dynamic initial data, see the :attr:`Form.initial` parameter.
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The use-case for this is when you want to display an "empty" form in which a
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field is initialized to a particular value. For example::
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>>> class CommentForm(forms.Form):
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... name = forms.CharField(initial='Your name')
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... url = forms.URLField(initial='http://')
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... comment = forms.CharField()
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>>> f = CommentForm(auto_id=False)
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>>> print f
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<tr><th>Name:</th><td><input type="text" name="name" value="Your name" /></td></tr>
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<tr><th>Url:</th><td><input type="text" name="url" value="http://" /></td></tr>
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<tr><th>Comment:</th><td><input type="text" name="comment" /></td></tr>
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You may be thinking, why not just pass a dictionary of the initial values as
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data when displaying the form? Well, if you do that, you'll trigger validation,
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and the HTML output will include any validation errors::
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>>> class CommentForm(forms.Form):
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... name = forms.CharField()
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... url = forms.URLField()
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... comment = forms.CharField()
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>>> default_data = {'name': 'Your name', 'url': 'http://'}
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>>> f = CommentForm(default_data, auto_id=False)
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>>> print f
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<tr><th>Name:</th><td><input type="text" name="name" value="Your name" /></td></tr>
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<tr><th>Url:</th><td><ul class="errorlist"><li>Enter a valid URL.</li></ul><input type="text" name="url" value="http://" /></td></tr>
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<tr><th>Comment:</th><td><ul class="errorlist"><li>This field is required.</li></ul><input type="text" name="comment" /></td></tr>
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This is why ``initial`` values are only displayed for unbound forms. For bound
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forms, the HTML output will use the bound data.
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Also note that ``initial`` values are *not* used as "fallback" data in
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validation if a particular field's value is not given. ``initial`` values are
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*only* intended for initial form display::
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>>> class CommentForm(forms.Form):
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... name = forms.CharField(initial='Your name')
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... url = forms.URLField(initial='http://')
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... comment = forms.CharField()
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>>> data = {'name': '', 'url': '', 'comment': 'Foo'}
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>>> f = CommentForm(data)
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>>> f.is_valid()
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False
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# The form does *not* fall back to using the initial values.
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>>> f.errors
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{'url': [u'This field is required.'], 'name': [u'This field is required.']}
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Instead of a constant, you can also pass any callable::
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>>> import datetime
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>>> class DateForm(forms.Form):
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... day = forms.DateField(initial=datetime.date.today)
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>>> print DateForm()
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<tr><th>Day:</th><td><input type="text" name="day" value="12/23/2008" /><td></tr>
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The callable will be evaluated only when the unbound form is displayed, not when it is defined.
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``widget``
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~~~~~~~~~~
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.. attribute:: Field.widget
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The ``widget`` argument lets you specify a ``Widget`` class to use when
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rendering this ``Field``. See :ref:`ref-forms-widgets` for more information.
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``help_text``
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~~~~~~~~~~~~~
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.. attribute:: Field.help_text
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The ``help_text`` argument lets you specify descriptive text for this
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``Field``. If you provide ``help_text``, it will be displayed next to the
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``Field`` when the ``Field`` is rendered by one of the convenience ``Form``
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methods (e.g., ``as_ul()``).
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Here's a full example ``Form`` that implements ``help_text`` for two of its
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fields. We've specified ``auto_id=False`` to simplify the output::
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>>> class HelpTextContactForm(forms.Form):
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... subject = forms.CharField(max_length=100, help_text='100 characters max.')
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... message = forms.CharField()
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... sender = forms.EmailField(help_text='A valid e-mail address, please.')
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... cc_myself = forms.BooleanField(required=False)
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>>> f = HelpTextContactForm(auto_id=False)
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>>> print f.as_table()
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<tr><th>Subject:</th><td><input type="text" name="subject" maxlength="100" /><br />100 characters max.</td></tr>
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<tr><th>Message:</th><td><input type="text" name="message" /></td></tr>
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<tr><th>Sender:</th><td><input type="text" name="sender" /><br />A valid e-mail address, please.</td></tr>
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<tr><th>Cc myself:</th><td><input type="checkbox" name="cc_myself" /></td></tr>
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>>> print f.as_ul()
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<li>Subject: <input type="text" name="subject" maxlength="100" /> 100 characters max.</li>
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<li>Message: <input type="text" name="message" /></li>
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<li>Sender: <input type="text" name="sender" /> A valid e-mail address, please.</li>
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<li>Cc myself: <input type="checkbox" name="cc_myself" /></li>
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>>> print f.as_p()
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<p>Subject: <input type="text" name="subject" maxlength="100" /> 100 characters max.</p>
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<p>Message: <input type="text" name="message" /></p>
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<p>Sender: <input type="text" name="sender" /> A valid e-mail address, please.</p>
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<p>Cc myself: <input type="checkbox" name="cc_myself" /></p>
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``error_messages``
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~~~~~~~~~~~~~~~~~~
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.. versionadded:: 1.0
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.. attribute:: Field.error_messages
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The ``error_messages`` argument lets you override the default messages that the
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field will raise. Pass in a dictionary with keys matching the error messages you
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want to override. For example, here is the default error message::
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>>> generic = forms.CharField()
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>>> generic.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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And here is a custom error message::
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>>> name = forms.CharField(error_messages={'required': 'Please enter your name'})
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>>> name.clean('')
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Traceback (most recent call last):
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...
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ValidationError: [u'Please enter your name']
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In the `built-in Field classes`_ section below, each ``Field`` defines the
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error message keys it uses.
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``validators``
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~~~~~~~~~~~~~~
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.. versionadded:: 1.2
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.. attribute:: Field.validators
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The ``validators`` argument lets you provide a list of validation functions
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for this field.
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See the :ref:`validators documentation <ref-validators>` for more information.
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Built-in ``Field`` classes
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--------------------------
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Naturally, the ``forms`` library comes with a set of ``Field`` classes that
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represent common validation needs. This section documents each built-in field.
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For each field, we describe the default widget used if you don't specify
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``widget``. We also specify the value returned when you provide an empty value
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(see the section on ``required`` above to understand what that means).
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``BooleanField``
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~~~~~~~~~~~~~~~~
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.. class:: BooleanField(**kwargs)
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* Default widget: ``CheckboxInput``
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* Empty value: ``False``
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* Normalizes to: A Python ``True`` or ``False`` value.
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* Validates that the value is ``True`` (e.g. the check box is checked) if
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the field has ``required=True``.
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* Error message keys: ``required``
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.. versionchanged:: 1.0
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The empty value for a ``CheckboxInput`` (and hence the standard
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``BooleanField``) has changed to return ``False`` instead of ``None`` in
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the Django 1.0.
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.. note::
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Since all ``Field`` subclasses have ``required=True`` by default, the
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validation condition here is important. If you want to include a boolean
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in your form that can be either ``True`` or ``False`` (e.g. a checked or
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unchecked checkbox), you must remember to pass in ``required=False`` when
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creating the ``BooleanField``.
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``CharField``
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~~~~~~~~~~~~~
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.. class:: CharField(**kwargs)
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* Default widget: ``TextInput``
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* Empty value: ``''`` (an empty string)
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* Normalizes to: A Unicode object.
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* Validates ``max_length`` or ``min_length``, if they are provided.
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Otherwise, all inputs are valid.
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* Error message keys: ``required``, ``max_length``, ``min_length``
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Has two optional arguments for validation:
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.. attribute:: CharField.max_length
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.. attribute:: CharField.min_length
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If provided, these arguments ensure that the string is at most or at least
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the given length.
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``ChoiceField``
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~~~~~~~~~~~~~~~
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.. class:: ChoiceField(**kwargs)
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* Default widget: ``Select``
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* Empty value: ``''`` (an empty string)
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* Normalizes to: A Unicode object.
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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 one extra required argument:
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.. attribute:: ChoiceField.choices
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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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.. class:: DateField(**kwargs)
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* Default widget: ``DateInput``
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* Empty value: ``None``
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* Normalizes to: A Python ``datetime.date`` object.
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* Validates that the given value is either a ``datetime.date``,
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``datetime.datetime`` or string formatted in a particular date format.
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* Error message keys: ``required``, ``invalid``
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Takes one optional argument:
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.. attribute:: DateField.input_formats
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A list of formats used to attempt to convert a string to a valid
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``datetime.date`` object.
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If no ``input_formats`` argument is provided, the default input formats are::
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'%Y-%m-%d', '%m/%d/%Y', '%m/%d/%y', # '2006-10-25', '10/25/2006', '10/25/06'
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'%b %d %Y', '%b %d, %Y', # 'Oct 25 2006', 'Oct 25, 2006'
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'%d %b %Y', '%d %b, %Y', # '25 Oct 2006', '25 Oct, 2006'
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'%B %d %Y', '%B %d, %Y', # 'October 25 2006', 'October 25, 2006'
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'%d %B %Y', '%d %B, %Y', # '25 October 2006', '25 October, 2006'
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.. versionchanged:: 1.1
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The ``DateField`` previously used a ``TextInput`` widget by default. It now
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uses a ``DateInput`` widget.
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``DateTimeField``
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~~~~~~~~~~~~~~~~~
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.. class:: DateTimeField(**kwargs)
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* Default widget: ``DateTimeInput``
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* Empty value: ``None``
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* Normalizes to: A Python ``datetime.datetime`` object.
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* Validates that the given value is either a ``datetime.datetime``,
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``datetime.date`` or string formatted in a particular datetime format.
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* Error message keys: ``required``, ``invalid``
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Takes one optional argument:
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.. attribute:: DateTimeField.input_formats
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A list of formats used to attempt to convert a string to a valid
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``datetime.datetime`` object.
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If no ``input_formats`` argument is provided, the default input formats are::
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'%Y-%m-%d %H:%M:%S', # '2006-10-25 14:30:59'
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'%Y-%m-%d %H:%M', # '2006-10-25 14:30'
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'%Y-%m-%d', # '2006-10-25'
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'%m/%d/%Y %H:%M:%S', # '10/25/2006 14:30:59'
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'%m/%d/%Y %H:%M', # '10/25/2006 14:30'
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'%m/%d/%Y', # '10/25/2006'
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'%m/%d/%y %H:%M:%S', # '10/25/06 14:30:59'
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'%m/%d/%y %H:%M', # '10/25/06 14:30'
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'%m/%d/%y', # '10/25/06'
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.. versionchanged:: 1.0
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The ``DateTimeField`` used to use a ``TextInput`` widget by default. This has now changed.
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``DecimalField``
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~~~~~~~~~~~~~~~~
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.. versionadded:: 1.0
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.. class:: DecimalField(**kwargs)
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* Default widget: ``TextInput``
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* Empty value: ``None``
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* Normalizes to: A Python ``decimal``.
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* Validates that the given value is a decimal. Leading and trailing
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whitespace is ignored.
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* Error message keys: ``required``, ``invalid``, ``max_value``,
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``min_value``, ``max_digits``, ``max_decimal_places``,
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``max_whole_digits``
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Takes four optional arguments:
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.. attribute:: DecimalField.max_value
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.. attribute:: DecimalField.min_value
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These attributes define the limits for the fields value.
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.. attribute:: DecimalField.max_digits
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The maximum number of digits (those before the decimal point plus those
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after the decimal point, with leading zeros stripped) permitted in the
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value.
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.. attribute:: DecimalField.decimal_places
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The maximum number of decimal places permitted.
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``EmailField``
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~~~~~~~~~~~~~~
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.. class:: EmailField(**kwargs)
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* Default widget: ``TextInput``
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* Empty value: ``''`` (an empty string)
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* Normalizes to: A Unicode object.
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* Validates that the given value is a valid e-mail address, using a
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moderately complex regular expression.
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* Error message keys: ``required``, ``invalid``
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Has two optional arguments for validation, ``max_length`` and ``min_length``.
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If provided, these arguments ensure that the string is at most or at least the
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given length.
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``FileField``
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~~~~~~~~~~~~~
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.. versionadded:: 1.0
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.. class:: FileField(**kwargs)
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* Default widget: ``FileInput``
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* Empty value: ``None``
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* Normalizes to: An ``UploadedFile`` object that wraps the file content
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and file name into a single object.
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* Validates that non-empty file data has been bound to the form.
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* Error message keys: ``required``, ``invalid``, ``missing``, ``empty``
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To learn more about the ``UploadedFile`` object, see the :ref:`file uploads
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documentation <topics-http-file-uploads>`.
|
|
|
|
When you use a ``FileField`` in a form, you must also remember to
|
|
:ref:`bind the file data to the form <binding-uploaded-files>`.
|
|
|
|
``FilePathField``
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
.. versionadded:: 1.0
|
|
|
|
.. class:: FilePathField(**kwargs)
|
|
|
|
* Default widget: ``Select``
|
|
* Empty value: ``None``
|
|
* Normalizes to: A unicode object
|
|
* Validates that the selected choice exists in the list of choices.
|
|
* Error message keys: ``required``, ``invalid_choice``
|
|
|
|
The field allows choosing from files inside a certain directory. It takes three
|
|
extra arguments; only ``path`` is required:
|
|
|
|
.. attribute:: FilePathField.path
|
|
|
|
The absolute path to the directory whose contents you want listed. This
|
|
directory must exist.
|
|
|
|
.. attribute:: FilePathField.recursive
|
|
|
|
If ``False`` (the default) only the direct contents of ``path`` will be
|
|
offered as choices. If ``True``, the directory will be descended into
|
|
recursively and all descendants will be listed as choices.
|
|
|
|
.. attribute:: FilePathField.match
|
|
|
|
A regular expression pattern; only files with names matching this expression
|
|
will be allowed as choices.
|
|
|
|
``FloatField``
|
|
~~~~~~~~~~~~~~
|
|
|
|
* Default widget: ``TextInput``
|
|
* Empty value: ``None``
|
|
* Normalizes to: A Python float.
|
|
* Validates that the given value is an float. Leading and trailing
|
|
whitespace is allowed, as in Python's ``float()`` function.
|
|
* Error message keys: ``required``, ``invalid``, ``max_value``,
|
|
``min_value``
|
|
|
|
Takes two optional arguments for validation, ``max_value`` and ``min_value``.
|
|
These control the range of values permitted in the field.
|
|
|
|
``ImageField``
|
|
~~~~~~~~~~~~~~
|
|
|
|
.. versionadded:: 1.0
|
|
|
|
.. class:: ImageField(**kwargs)
|
|
|
|
* Default widget: ``FileInput``
|
|
* Empty value: ``None``
|
|
* Normalizes to: An ``UploadedFile`` object that wraps the file content
|
|
and file name into a single object.
|
|
* Validates that file data has been bound to the form, and that the
|
|
file is of an image format understood by PIL.
|
|
* Error message keys: ``required``, ``invalid``, ``missing``, ``empty``,
|
|
``invalid_image``
|
|
|
|
Using an ImageField requires that the `Python Imaging Library`_ is installed.
|
|
|
|
When you use an ``ImageField`` on a form, you must also remember to
|
|
:ref:`bind the file data to the form <binding-uploaded-files>`.
|
|
|
|
.. _Python Imaging Library: http://www.pythonware.com/products/pil/
|
|
|
|
``IntegerField``
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
.. class:: IntegerField(**kwargs)
|
|
|
|
* Default widget: ``TextInput``
|
|
* Empty value: ``None``
|
|
* Normalizes to: A Python integer or long integer.
|
|
* Validates that the given value is an integer. Leading and trailing
|
|
whitespace is allowed, as in Python's ``int()`` function.
|
|
* Error message keys: ``required``, ``invalid``, ``max_value``,
|
|
``min_value``
|
|
|
|
Takes two optional arguments for validation:
|
|
|
|
.. attribute:: IntegerField.max_value
|
|
.. attribute:: IntegerField.min_value
|
|
|
|
These control the range of values permitted in the field.
|
|
|
|
``IPAddressField``
|
|
~~~~~~~~~~~~~~~~~~
|
|
|
|
.. class:: IPAddressField(**kwargs)
|
|
|
|
* Default widget: ``TextInput``
|
|
* Empty value: ``''`` (an empty string)
|
|
* Normalizes to: A Unicode object.
|
|
* Validates that the given value is a valid IPv4 address, using a regular
|
|
expression.
|
|
* Error message keys: ``required``, ``invalid``
|
|
|
|
``MultipleChoiceField``
|
|
~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
.. class:: MultipleChoiceField(**kwargs)
|
|
|
|
* Default widget: ``SelectMultiple``
|
|
* Empty value: ``[]`` (an empty list)
|
|
* Normalizes to: A list of Unicode objects.
|
|
* Validates that every value in the given list of values exists in the list
|
|
of choices.
|
|
* Error message keys: ``required``, ``invalid_choice``, ``invalid_list``
|
|
|
|
Takes one extra argument, ``choices``, as for ``ChoiceField``.
|
|
|
|
``NullBooleanField``
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
.. class:: NullBooleanField(**kwargs)
|
|
|
|
* Default widget: ``NullBooleanSelect``
|
|
* Empty value: ``None``
|
|
* Normalizes to: A Python ``True``, ``False`` or ``None`` value.
|
|
* Validates nothing (i.e., it never raises a ``ValidationError``).
|
|
|
|
``RegexField``
|
|
~~~~~~~~~~~~~~
|
|
|
|
.. class:: RegexField(**kwargs)
|
|
|
|
* Default widget: ``TextInput``
|
|
* Empty value: ``''`` (an empty string)
|
|
* Normalizes to: A Unicode object.
|
|
* Validates that the given value matches against a certain regular
|
|
expression.
|
|
* Error message keys: ``required``, ``invalid``
|
|
|
|
Takes one required argument:
|
|
|
|
.. attribute:: RegexField.regex
|
|
|
|
A regular expression specified either as a string or a compiled regular
|
|
expression object.
|
|
|
|
Also takes ``max_length`` and ``min_length``, which work just as they do for
|
|
``CharField``.
|
|
|
|
The optional argument ``error_message`` is also accepted for backwards
|
|
compatibility. The preferred way to provide an error message is to use the
|
|
``error_messages`` argument, passing a dictionary with ``'invalid'`` as a key
|
|
and the error message as the value.
|
|
|
|
``TimeField``
|
|
~~~~~~~~~~~~~
|
|
|
|
.. class:: TimeField(**kwargs)
|
|
|
|
* Default widget: ``TextInput``
|
|
* Empty value: ``None``
|
|
* Normalizes to: A Python ``datetime.time`` object.
|
|
* Validates that the given value is either a ``datetime.time`` or string
|
|
formatted in a particular time format.
|
|
* Error message keys: ``required``, ``invalid``
|
|
|
|
Takes one optional argument:
|
|
|
|
.. attribute:: TimeField.input_formats
|
|
|
|
A list of formats used to attempt to convert a string to a valid
|
|
``datetime.time`` object.
|
|
|
|
If no ``input_formats`` argument is provided, the default input formats are::
|
|
|
|
'%H:%M:%S', # '14:30:59'
|
|
'%H:%M', # '14:30'
|
|
|
|
``URLField``
|
|
~~~~~~~~~~~~
|
|
|
|
.. class:: URLField(**kwargs)
|
|
|
|
* Default widget: ``TextInput``
|
|
* Empty value: ``''`` (an empty string)
|
|
* Normalizes to: A Unicode object.
|
|
* Validates that the given value is a valid URL.
|
|
* Error message keys: ``required``, ``invalid``, ``invalid_link``
|
|
|
|
Takes the following optional arguments:
|
|
|
|
|
|
.. attribute:: URLField.max_length
|
|
.. attribute:: URLField.min_length
|
|
|
|
Same as ``CharField.max_length`` and ``CharField.min_length``.
|
|
|
|
.. attribute:: URLField.verify_exists
|
|
|
|
If ``True``, the validator will attempt to load the given URL, raising
|
|
``ValidationError`` if the page gives a 404. Defaults to ``False``.
|
|
|
|
.. attribute:: URLField.validator_user_agent
|
|
|
|
String used as the user-agent used when checking for a URL's existence.
|
|
Defaults to the value of the ``URL_VALIDATOR_USER_AGENT`` setting.
|
|
|
|
Slightly complex built-in ``Field`` classes
|
|
-------------------------------------------
|
|
|
|
The following are not yet documented.
|
|
|
|
.. class:: ComboField(**kwargs)
|
|
|
|
.. class:: MultiValueField(**kwargs)
|
|
|
|
.. class:: SplitDateTimeField(**kwargs)
|
|
|
|
* Default widget: ``SplitDateTimeWidget``
|
|
* Empty value: ``None``
|
|
* Normalizes to: A Python ``datetime.datetime`` object.
|
|
* Validates that the given value is a ``datetime.datetime`` or string
|
|
formatted in a particular datetime format.
|
|
* Error message keys: ``required``, ``invalid``
|
|
|
|
Takes two optional arguments:
|
|
|
|
.. attribute:: SplitDateTimeField.input_date_formats
|
|
|
|
A list of formats used to attempt to convert a string to a valid
|
|
``datetime.date`` object.
|
|
|
|
If no ``input_date_formats`` argument is provided, the default input formats
|
|
for ``DateField`` are used.
|
|
|
|
.. attribute:: SplitDateTimeField.input_time_formats
|
|
|
|
A list of formats used to attempt to convert a string to a valid
|
|
``datetime.time`` object.
|
|
|
|
If no ``input_time_formats`` argument is provided, the default input formats
|
|
for ``TimeField`` are used.
|
|
|
|
.. versionchanged:: 1.1
|
|
The ``SplitDateTimeField`` previously used two ``TextInput`` widgets by
|
|
default. The ``input_date_formats`` and ``input_time_formats`` arguments
|
|
are also new.
|
|
|
|
Fields which handle relationships
|
|
---------------------------------
|
|
|
|
For representing relationships between models, two fields are
|
|
provided which can derive their choices from a ``QuerySet``:
|
|
|
|
.. class:: ModelChoiceField(**kwargs)
|
|
.. class:: ModelMultipleChoiceField(**kwargs)
|
|
|
|
These fields place one or more model objects into the ``cleaned_data``
|
|
dictionary of forms in which they're used. Both of these fields have an
|
|
additional required argument:
|
|
|
|
.. attribute:: ModelChoiceField.queryset
|
|
|
|
A ``QuerySet`` of model objects from which the choices for the
|
|
field will be derived, and which will be used to validate the
|
|
user's selection.
|
|
|
|
``ModelChoiceField``
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Allows the selection of a single model object, suitable for
|
|
representing a foreign key.
|
|
|
|
The ``__unicode__`` method of the model will be called to generate
|
|
string representations of the objects for use in the field's choices;
|
|
to provide customized representations, subclass ``ModelChoiceField``
|
|
and override ``label_from_instance``. This method will receive a model
|
|
object, and should return a string suitable for representing it. For
|
|
example::
|
|
|
|
class MyModelChoiceField(ModelChoiceField):
|
|
def label_from_instance(self, obj):
|
|
return "My Object #%i" % obj.id
|
|
|
|
.. attribute:: ModelChoiceField.empty_label
|
|
|
|
By default the ``<select>`` widget used by ``ModelChoiceField`` will have a
|
|
an empty choice at the top of the list. You can change the text of this label
|
|
(which is ``"---------"`` by default) with the ``empty_label`` attribute, or
|
|
you can disable the empty label entirely by setting ``empty_label`` to
|
|
``None``::
|
|
|
|
# A custom empty label
|
|
field1 = forms.ModelChoiceField(queryset=..., empty_label="(Nothing)")
|
|
|
|
# No empty label
|
|
field2 = forms.ModelChoiceField(queryset=..., empty_label=None)
|
|
|
|
Note that if a ``ModelChoiceField`` is required and has a default
|
|
initial value, no empty choice is created (regardless of the value
|
|
of ``empty_label``).
|
|
|
|
``ModelMultipleChoiceField``
|
|
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
Allows the selection of one or more model objects, suitable for
|
|
representing a many-to-many relation. As with ``ModelChoiceField``,
|
|
you can use ``label_from_instance`` to customize the object
|
|
representations.
|
|
|
|
Creating custom fields
|
|
----------------------
|
|
|
|
If the built-in ``Field`` classes don't meet your needs, you can easily create
|
|
custom ``Field`` classes. To do this, just create a subclass of
|
|
``django.forms.Field``. Its only requirements are that it implement a
|
|
``clean()`` method and that its ``__init__()`` method accept the core arguments
|
|
mentioned above (``required``, ``label``, ``initial``, ``widget``,
|
|
``help_text``).
|