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Added documentation for widgets in newforms.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5867 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Russell Keith-Magee 2007-08-12 06:25:05 +00:00
parent dd0f5d9284
commit 3d012a18ce

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@ -962,7 +962,7 @@ validation if a particular field's value is not given. ``initial`` values are
~~~~~~~~~~
The ``widget`` argument lets you specify a ``Widget`` class to use when
rendering this ``Field``. See "Widgets" below for more information.
rendering this ``Field``. See "Widgets"_ below for more information.
``help_text``
~~~~~~~~~~~~~
@ -1437,6 +1437,156 @@ like so::
senders = MultiEmailField()
cc_myself = forms.BooleanField()
Widgets
=======
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:
============================ ===========================================
Widget HTML Equivalent
============================ ===========================================
``TextInput`` ``<input type='text' ...``
``PasswordInput`` ``<input type='password' ...``
``HiddenInput`` ``<input type='hidden' ...``
``MultipleHiddenInput`` Multiple ``<input type='hidden' ...``
instances.
``FileInput`` ``<input type='file' ...``
``Textarea`` ``<textarea>...</textarea>``
``CheckboxInput`` ``<input type='checkbox' ...``
``Select`` ``<select><option ...``
``NullBooleanSelect`` Select widget with options 'Unknown',
'Yes' and 'No'
``SelectMultiple`` ``<select multiple='multiple'><option ...``
``RadioSelect`` ``<ul><li><input type='radio' ...``
``CheckboxSelectMultiple`` ``<ul><li><input type='checkbox' ...``
``MultiWidget`` Wrapper around multiple other widgets
``SplitDateTimeWidget`` Wrapper around two ``TextInput`` widgets:
one for the Date, and one for the Time.
============================ ===========================================
Specifying widgets
------------------
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::
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 inputs 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 specify a
custom widget for your fields, and specify some attributes to use
when rendering those widgets::
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>
Custom Widgets
--------------
When you start to write a lot of forms, you will probably find that you will
reuse certain sets of widget attributes over and over again. Rather than
repeat these attribute definitions every time you need them, Django allows
you to capture those definitions as a custom widget.
For example, if you find that you are including a lot of comment fields on forms,
you could capture the idea of a ``TextInput`` with a specific ``size`` attribute
as a custom extension to the ``TextInput`` widget::
class CommentWidget(forms.TextInput):
def __init__(self, *args, **kwargs):
kwargs.setdefault('attrs',{}).update({'size': '40'})
super(forms.TextInput, self).__init__(*args, **kwargs)
Then you can use this widget in your forms::
class CommentForm(forms.Form):
name = forms.CharField()
url = forms.URLField()
comment = forms.CharField(widget=CommentWidget)
You can even customize your custom widget, in the same way as you would
any other widget. Adding a once-off class to your ``CommentWidget`` is as
simple as adding an attribute definition::
class CommentForm(forms.Form):
name = forms.CharField(max_length=20)
url = forms.URLField()
comment = forms.CharField(
widget=CommentWidget(attrs={'class': 'special'}))
Django also makes it easy to specify a custom field type that uses your custom
widget. For example, you could define a customized field type for comments
by defining::
class CommentInput(forms.CharField):
widget = CommentWidget
You can then use this field whenever you have a form that requires a comment::
class CommentForm(forms.Form):
name = forms.CharField()
url = forms.URLField()
comment = CommentInput()
Generating forms for models
===========================