lib/django-1.3/docs/ref/forms/widgets.txt

=======
Widgets
=======

.. module:: django.forms.widgets
   :synopsis: Django's built-in form widgets.

.. currentmodule:: django.forms

A widget is Django's representation of a HTML input element. The widget
handles the rendering of the HTML, and the extraction of data from a GET/POST
dictionary that corresponds to the widget.

Django provides a representation of all the basic HTML widgets, plus some
commonly used groups of widgets:

.. class:: TextInput

    Text input: ``<input type='text' ...>``

.. class:: PasswordInput

    Password input: ``<input type='password' ...>``

    Takes one optional argument:

    .. attribute:: PasswordInput.render_value

        Determines whether the widget will have a value filled in when the
        form is re-displayed after a validation error (default is ``False``).

.. versionchanged:: 1.3
    The default value for
    :attr:`~PasswordInput.render_value` was
    changed from ``True`` to ``False``

.. class:: HiddenInput

    Hidden input: ``<input type='hidden' ...>``

.. class:: MultipleHiddenInput

    Multiple ``<input type='hidden' ...>`` widgets.

.. class:: FileInput

    File upload input: ``<input type='file' ...>``

.. class:: ClearableFileInput

    .. versionadded:: 1.3

    File upload input: ``<input type='file' ...>``, with an additional checkbox
    input to clear the field's value, if the field is not required and has
    initial data.

.. class:: DateInput

    Date input as a simple text box: ``<input type='text' ...>``

    Takes one optional argument:

    .. attribute:: DateInput.format

        The format in which this field's initial value will be displayed.

    If no ``format`` argument is provided, the default format is ``'%Y-%m-%d'``.

.. class:: DateTimeInput

    Date/time input as a simple text box: ``<input type='text' ...>``

    Takes one optional argument:

    .. attribute:: DateTimeInput.format

        The format in which this field's initial value will be displayed.

    If no ``format`` argument is provided, the default format is ``'%Y-%m-%d
    %H:%M:%S'``.

.. class:: TimeInput

    Time input as a simple text box: ``<input type='text' ...>``

    Takes one optional argument:

    .. attribute:: TimeInput.format

        The format in which this field's initial value will be displayed.

    If no ``format`` argument is provided, the default format is ``'%H:%M:%S'``.

.. class:: Textarea

    Text area: ``<textarea>...</textarea>``

.. class:: CheckboxInput

    Checkbox: ``<input type='checkbox' ...>``

    Takes one optional argument:

    .. attribute:: CheckboxInput.check_test

        A callable that takes the value of the CheckBoxInput
        and returns ``True`` if the checkbox should be checked for
        that value.

.. class:: Select

    Select widget: ``<select><option ...>...</select>``

    Requires that your field provides :attr:`~Field.choices`.

.. class:: NullBooleanSelect

    Select widget with options 'Unknown', 'Yes' and 'No'

.. class:: SelectMultiple

    Select widget allowing multiple selection: ``<select
    multiple='multiple'>...</select>``

    Requires that your field provides :attr:`~Field.choices`.

.. class:: RadioSelect

    A list of radio buttons:

    .. code-block:: html

        <ul>
          <li><input type='radio' ...></li>
          ...
        </ul>

    Requires that your field provides :attr:`~Field.choices`.

.. class:: CheckboxSelectMultiple

    A list of checkboxes:

    .. code-block:: html

        <ul>
          <li><input type='checkbox' ...></li>
          ...
        </ul>

.. class:: MultiWidget

    Wrapper around multiple other widgets

.. class:: SplitDateTimeWidget

    Wrapper around two widgets: ``DateInput`` for the date, and ``TimeInput``
    for the time.

    Takes two optional arguments, ``date_format`` and ``time_format``, which
    work just like the ``format`` argument for ``DateInput`` and ``TimeInput``.

.. currentmodule:: django.forms.extras.widgets

.. class:: SelectDateWidget

    Wrapper around three select widgets: one each for month, day, and year.
    Note that this widget lives in a separate file from the standard widgets.

    Takes one optional argument:

    .. attribute:: List.years

        An optional list/tuple of years to use in the "year" select box.
        The default is a list containing the current year and the next 9 years.

    .. code-block:: python

        from django.forms.extras.widgets import SelectDateWidget

        date = forms.DateField(widget=SelectDateWidget())

Specifying widgets
------------------
.. currentmodule:: django.forms

.. attribute:: Form.widget

Whenever you specify a field on a form, Django will use a default widget
that is appropriate to the type of data that is to be displayed. To find
which widget is used on which field, see the documentation for the
built-in Field classes.

However, if you want to use a different widget for a field, you can -
just use the 'widget' argument on the field definition. For example::

    from django import forms

    class CommentForm(forms.Form):
        name = forms.CharField()
        url = forms.URLField()
        comment = forms.CharField(widget=forms.Textarea)

This would specify a form with a comment that uses a larger Textarea widget,
rather than the default TextInput widget.

Customizing widget instances
----------------------------

When Django renders a widget as HTML, it only renders the bare minimum
HTML - Django doesn't add a class definition, or any other widget-specific
attributes. This means that all 'TextInput' widgets will appear the same
on your Web page.

If you want to make one widget look different to another, you need to
specify additional attributes for each widget. When you specify a
widget, you can provide a list of attributes that will be added to the
rendered HTML for the widget.

For example, take the following simple form::

    class CommentForm(forms.Form):
        name = forms.CharField()
        url = forms.URLField()
        comment = forms.CharField()

This form will include three default TextInput widgets, with default rendering -
no CSS class, no extra attributes. This means that the input boxes provided for
each widget will be rendered exactly the same::

    >>> f = CommentForm(auto_id=False)
    >>> f.as_table()
    <tr><th>Name:</th><td><input type="text" name="name" /></td></tr>
    <tr><th>Url:</th><td><input type="text" name="url"/></td></tr>
    <tr><th>Comment:</th><td><input type="text" name="comment" /></td></tr>


On a real Web page, you probably don't want every widget to look the same. You
might want a larger input element for the comment, and you might want the 'name'
widget to have some special CSS class. To do this, you use the ``attrs``
argument when creating the widget:

.. attribute:: Widget.attrs

For example::

    class CommentForm(forms.Form):
        name = forms.CharField(
                    widget=forms.TextInput(attrs={'class':'special'}))
        url = forms.URLField()
        comment = forms.CharField(
                   widget=forms.TextInput(attrs={'size':'40'}))

Django will then include the extra attributes in the rendered output::

    >>> f = CommentForm(auto_id=False)
    >>> f.as_table()
    <tr><th>Name:</th><td><input type="text" name="name" class="special"/></td></tr>
    <tr><th>Url:</th><td><input type="text" name="url"/></td></tr>
    <tr><th>Comment:</th><td><input type="text" name="comment" size="40"/></td></tr>