Fixed #16264 -- Improved form widget documentation. Many thanks to Bas Peschier.
git-svn-id: http://code.djangoproject.com/svn/django/trunk@16408 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jannis Leidel
parent
e008fde23e
commit
662b372d02
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@ -278,6 +278,7 @@ as the rendered output.
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See the :ref:`format localization <format-localization>` documentation for
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more information.
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.. _built-in fields:
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Built-in ``Field`` classes
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--------------------------
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@ -11,9 +11,181 @@ A widget is Django's representation of a HTML input element. The widget
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handles the rendering of the HTML, and the extraction of data from a GET/POST
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dictionary that corresponds to the widget.
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Specifying widgets
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------------------
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Whenever you specify a field on a form, Django will use a default widget
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that is appropriate to the type of data that is to be displayed. To find
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which widget is used on which field, see the documentation about
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:ref:`built-in fields`.
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However, if you want to use a different widget for a field, you can
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just use the :attr:`~Field.widget` argument on the field definition. For
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example:
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.. code-block:: python
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from django import forms
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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(widget=forms.Textarea)
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This would specify a form with a comment that uses a larger :class:`Textarea`
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widget, rather than the default :class:`TextInput` widget.
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Setting arguments for widgets
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-----------------------------
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Many widgets have optional extra arguments; they can be set when defining the
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widget on the field. In the following example, the
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:attr:`~SelectDateWidget.years` attribute is set for a
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:class:`~django.forms.widgets.extras.SelectDateWidget`:
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.. code-block:: python
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from django.forms.fields import DateField, ChoiceField, MultipleChoiceField
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from django.forms.widgets import RadioSelect, CheckboxSelectMultiple
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from django.forms.widgets.extras import SelectDateWidget
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BIRTH_YEAR_CHOICES = ('1980', '1981', '1982')
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GENDER_CHOICES = (('m', 'Male'), ('f', 'Female'))
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FAVOURITE_COLORS_CHOICES = (('blue', 'Blue'),
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('green', 'Green'),
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('black', 'Black'))
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class SimpleForm(forms.Form):
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birth_year = DateField(widget=SelectDateWidget(years=YEAR_CHOICES))
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gender = ChoiceField(widget=RadioSelect, choices=RADIO_CHOICES)
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favourite_colors = forms.MultipleChoiceField(required=False,
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widget=CheckboxSelectMultiple, choices=CHECKBOX_CHOICES)
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See the :ref:`built-in widgets` for more information about which widgets
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are available and which arguments they accept.
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Widgets inheriting from the Select widget
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-----------------------------------------
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Widgets inheriting from the :class:`Select` widget deal with choices. They
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present the user with a list of options to choose from. The different widgets
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present this choice differently; the :class:`Select` widget itself uses a
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``<select>`` HTML list representation, while :class:`RadioSelect` uses radio
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buttons.
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:class:`Select` widgets are used by default on :class:`ChoiceField` fields. The
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choices displayed on the widget are inherited from the :class:`ChoiceField` and
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changing :attr:`ChoiceField.choices` will update :attr:`Select.choices`. For
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example:
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.. code-block:: python
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>>> from django import forms
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>>> CHOICES = (('1', 'First',), ('2', 'Second',)))
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>>> choice_field = forms.ChoiceField(widget=forms.RadioSelect, choices=CHOICES)
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>>> choice_field.choices
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[('1', 'First'), ('2', 'Second')]
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>>> choice_field.widget.choices
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[('1', 'First'), ('2', 'Second')]
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>>> choice_field.widget.choices = ()
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>>> choice_field.choices = (('1', 'First and only',),)
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>>> choice_field.widget.choices
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[('1', 'First and only')]
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Widgets which offer a :attr:`~Select.choices` attribute can however be used
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with fields which are not based on choice -- such as a :class:`CharField` --
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but it is recommended to use a :class:`ChoiceField`-based field when the
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choices are inherent to the model and not just the representational widget.
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Customizing widget instances
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----------------------------
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When Django renders a widget as HTML, it only renders the bare minimum
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HTML - Django doesn't add a class definition, or any other widget-specific
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attributes. This means that all :class:`TextInput` widgets will appear the same
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on your Web page.
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If you want to make one widget look different to another, you need to
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specify additional attributes for each widget. When you specify a
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widget, you can provide a list of attributes that will be added to the
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rendered HTML for the widget.
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For example, take the following simple form:
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.. code-block:: python
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from django import forms
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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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This form will include three default :class:`TextInput` widgets, with default
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rendering -- no CSS class, no extra attributes. This means that the input boxes
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provided for each widget will be rendered exactly the same:
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.. code-block:: python
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>>> f = CommentForm(auto_id=False)
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>>> f.as_table()
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<tr><th>Name:</th><td><input type="text" name="name" /></td></tr>
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<tr><th>Url:</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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On a real Web page, you probably don't want every widget to look the same. You
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might want a larger input element for the comment, and you might want the
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'name' widget to have some special CSS class. To do this, you use the
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:attr:`Widget.attrs` argument when creating the widget:
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For example:
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.. code-block:: python
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class CommentForm(forms.Form):
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name = forms.CharField(
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widget=forms.TextInput(attrs={'class':'special'}))
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url = forms.URLField()
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comment = forms.CharField(
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widget=forms.TextInput(attrs={'size':'40'}))
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Django will then include the extra attributes in the rendered output:
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.. code-block:: python
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>>> f = CommentForm(auto_id=False)
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>>> f.as_table()
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<tr><th>Name:</th><td><input type="text" name="name" class="special"/></td></tr>
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<tr><th>Url:</th><td><input type="text" name="url"/></td></tr>
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<tr><th>Comment:</th><td><input type="text" name="comment" size="40"/></td></tr>
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.. _built-in widgets:
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Built-in widgets
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----------------
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Django provides a representation of all the basic HTML widgets, plus some
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commonly used groups of widgets:
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.. class:: Widget
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This abstract class cannot be rendered, but provides the basic attribute :attr:`~Widget.attrs`.
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.. attribute:: Widget.attrs
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A dictionary containing HTML attributes to be set on the rendered widget.
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.. code-block:: python
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>>> name = forms.TextInput(attrs={'size': 10, 'title': 'Your name',})
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>>> name.render('name', 'A name')
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u'<input title="Your name" type="text" name="name" value="A name" size="10" />'
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.. class:: TextInput
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Text input: ``<input type='text' ...>``
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@ -42,6 +214,15 @@ commonly used groups of widgets:
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Multiple ``<input type='hidden' ...>`` widgets.
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A widget that handles multiple hidden widgets for fields that have a list
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of values.
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.. attribute:: MultipleHiddenInput.choices
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This attribute is optional when the field does not have a
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:attr:`~Field.choices` attribute. If it does, it will override anything
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you set here when the attribute is updated on the :class:`Field`.
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.. class:: FileInput
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File upload input: ``<input type='file' ...>``
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@ -64,7 +245,9 @@ commonly used groups of widgets:
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The format in which this field's initial value will be displayed.
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If no ``format`` argument is provided, the default format is ``'%Y-%m-%d'``.
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If no ``format`` argument is provided, the default format is the first
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format found in :setting:`DATE_INPUT_FORMATS` and respects
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:ref:`format-localization`.
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.. class:: DateTimeInput
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@ -76,8 +259,9 @@ commonly used groups of widgets:
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The format in which this field's initial value will be displayed.
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If no ``format`` argument is provided, the default format is ``'%Y-%m-%d
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%H:%M:%S'``.
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If no ``format`` argument is provided, the default format is the first
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format found in :setting:`DATETIME_INPUT_FORMATS` and respects
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:ref:`format-localization`.
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.. class:: TimeInput
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@ -89,7 +273,9 @@ commonly used groups of widgets:
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The format in which this field's initial value will be displayed.
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If no ``format`` argument is provided, the default format is ``'%H:%M:%S'``.
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If no ``format`` argument is provided, the default format is the first
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format found in :setting:`TIME_INPUT_FORMATS` and respects
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:ref:`format-localization`.
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.. class:: Textarea
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@ -103,15 +289,18 @@ commonly used groups of widgets:
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.. attribute:: CheckboxInput.check_test
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A callable that takes the value of the CheckBoxInput
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and returns ``True`` if the checkbox should be checked for
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that value.
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A callable that takes the value of the CheckBoxInput and returns
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``True`` if the checkbox should be checked for that value.
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.. class:: Select
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Select widget: ``<select><option ...>...</select>``
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Requires that your field provides :attr:`~Field.choices`.
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.. attribute:: Select.choices
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This attribute is optional when the field does not have a
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:attr:`~Field.choices` attribute. If it does, it will override anything
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you set here when the attribute is updated on the :class:`Field`.
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.. class:: NullBooleanSelect
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@ -119,14 +308,12 @@ commonly used groups of widgets:
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.. class:: SelectMultiple
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Select widget allowing multiple selection: ``<select
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multiple='multiple'>...</select>``
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Requires that your field provides :attr:`~Field.choices`.
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Similar to :class:`Select`, but allows multiple selection:
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``<select multiple='multiple'>...</select>``
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.. class:: RadioSelect
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A list of radio buttons:
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Similar to :class:`Select`, but rendered as a list of radio buttons:
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.. code-block:: html
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@ -135,11 +322,10 @@ commonly used groups of widgets:
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...
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</ul>
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Requires that your field provides :attr:`~Field.choices`.
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.. class:: CheckboxSelectMultiple
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A list of checkboxes:
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Similar to :class:`SelectMultiple`, but rendered as a list of check
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buttons:
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.. code-block:: html
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@ -150,111 +336,83 @@ commonly used groups of widgets:
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.. class:: MultiWidget
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Wrapper around multiple other widgets
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Wrapper around multiple other widgets. You'll probably want to use this
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class with :class:`MultiValueField`.
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.. class:: SplitDateTimeWidget
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Its ``render()`` method is different than other widgets', because it has to
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figure out how to split a single value for display in multiple widgets.
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Wrapper around two widgets: ``DateInput`` for the date, and ``TimeInput``
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for the time.
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Subclasses may implement ``format_output``, which takes the list of
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rendered widgets and returns a string of HTML that formats them any way
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you'd like.
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Takes two optional arguments, ``date_format`` and ``time_format``, which
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work just like the ``format`` argument for ``DateInput`` and ``TimeInput``.
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The ``value`` argument used when rendering can be one of two things:
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.. currentmodule:: django.forms.extras.widgets
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* A ``list``.
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* A single value (e.g., a string) that is the "compressed" representation
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of a ``list`` of values.
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.. class:: SelectDateWidget
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Wrapper around three select widgets: one each for month, day, and year.
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Note that this widget lives in a separate file from the standard widgets.
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Takes one optional argument:
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.. attribute:: List.years
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An optional list/tuple of years to use in the "year" select box.
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The default is a list containing the current year and the next 9 years.
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In the second case -- i.e., if the value is *not* a list -- ``render()``
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will first decompress the value into a ``list`` before rendering it. It
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does so by calling the ``decompress()`` method, which
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:class:`MultiWidget`'s subclasses must implement. This method takes a
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single "compressed" value and returns a ``list``. An example of this is how
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:class:`SplitDateTimeWidget` turns a :class:`datetime` value into a list
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with date and time split into two seperate values:
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.. code-block:: python
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from django.forms.extras.widgets import SelectDateWidget
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class SplitDateTimeWidget(MultiWidget):
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date = forms.DateField(widget=SelectDateWidget())
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# ...
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Specifying widgets
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------------------
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.. currentmodule:: django.forms
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def decompress(self, value):
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if value:
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return [value.date(), value.time().replace(microsecond=0)]
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return [None, None]
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.. attribute:: Form.widget
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When ``render()`` executes its HTML rendering, each value in the list is
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rendered with the corresponding widget -- the first value is rendered in
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the first widget, the second value is rendered in the second widget, etc.
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Whenever you specify a field on a form, Django will use a default widget
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that is appropriate to the type of data that is to be displayed. To find
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which widget is used on which field, see the documentation for the
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built-in Field classes.
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:class:`MultiWidget` has one required argument:
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However, if you want to use a different widget for a field, you can -
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just use the 'widget' argument on the field definition. For example::
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.. attribute:: MultiWidget.widgets
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from django import forms
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An iterable containing the widgets needed.
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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(widget=forms.Textarea)
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.. class:: SplitDateTimeWidget
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This would specify a form with a comment that uses a larger Textarea widget,
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rather than the default TextInput widget.
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Wrapper (using :class:`MultiWidget`) around two widgets: :class:`DateInput`
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for the date, and :class:`TimeInput` for the time.
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Customizing widget instances
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----------------------------
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``SplitDateTimeWidget`` has two optional attributes:
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When Django renders a widget as HTML, it only renders the bare minimum
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HTML - Django doesn't add a class definition, or any other widget-specific
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attributes. This means that all 'TextInput' widgets will appear the same
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on your Web page.
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.. attribute:: SplitDateTimeWidget.date_format
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If you want to make one widget look different to another, you need to
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specify additional attributes for each widget. When you specify a
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widget, you can provide a list of attributes that will be added to the
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rendered HTML for the widget.
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Similar to :attr:`DateInput.format`
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For example, take the following simple form::
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.. attribute:: SplitDateTimeWidget.time_format
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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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|
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This form will include three default TextInput widgets, with default rendering -
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no CSS class, no extra attributes. This means that the input boxes provided for
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each widget will be rendered exactly the same::
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|
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>>> f = CommentForm(auto_id=False)
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>>> f.as_table()
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<tr><th>Name:</th><td><input type="text" name="name" /></td></tr>
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<tr><th>Url:</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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Similar to :attr:`TimeInput.format`
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On a real Web page, you probably don't want every widget to look the same. You
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might want a larger input element for the comment, and you might want the 'name'
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widget to have some special CSS class. To do this, you use the ``attrs``
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argument when creating the widget:
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.. class:: SplitHiddenDateTimeWidget
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.. attribute:: Widget.attrs
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Similar to :class:`SplitDateTimeWidget`, but uses :class:`HiddenInput` for
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both date and time.
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For example::
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.. currentmodule:: django.forms.widgets.extras
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class CommentForm(forms.Form):
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name = forms.CharField(
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widget=forms.TextInput(attrs={'class':'special'}))
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url = forms.URLField()
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comment = forms.CharField(
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widget=forms.TextInput(attrs={'size':'40'}))
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.. class:: SelectDateWidget
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Django will then include the extra attributes in the rendered output::
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Wrapper around three :class:`~django.forms.Select` widgets: one each for
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month, day, and year. Note that this widget lives in a separate file from
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the standard widgets.
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>>> f = CommentForm(auto_id=False)
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>>> f.as_table()
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<tr><th>Name:</th><td><input type="text" name="name" class="special"/></td></tr>
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<tr><th>Url:</th><td><input type="text" name="url"/></td></tr>
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<tr><th>Comment:</th><td><input type="text" name="comment" size="40"/></td></tr>
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Takes one optional argument:
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.. attribute:: SelectDateWidget.years
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An optional list/tuple of years to use in the "year" select box.
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The default is a list containing the current year and the next 9 years.
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|
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