Widgets¶
A widget is Django’s representation of an 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.
The HTML generated by the built-in widgets uses HTML5 syntax, targeting
<!DOCTYPE html>. For example, it uses boolean attributes such as checked
rather than the XHTML style of checked='checked'.
Πρακτική συμβουλή
Widgets should not be confused with the form fields. Form fields deal with the logic of input validation and are used directly in templates. Widgets deal with rendering of HTML form input elements on the web page and extraction of raw submitted data. However, widgets do need to be assigned to form fields.
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 about 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.
Setting arguments for widgets¶
Many widgets have optional extra arguments; they can be set when defining the
widget on the field. In the following example, the
years attribute is set for a
SelectDateWidget:
from django import forms
BIRTH_YEAR_CHOICES = ('1980', '1981', '1982')
FAVORITE_COLORS_CHOICES = (
('blue', 'Blue'),
('green', 'Green'),
('black', 'Black'),
)
class SimpleForm(forms.Form):
birth_year = forms.DateField(widget=forms.SelectDateWidget(years=BIRTH_YEAR_CHOICES))
favorite_colors = forms.MultipleChoiceField(
required=False,
widget=forms.CheckboxSelectMultiple,
choices=FAVORITE_COLORS_CHOICES,
)
See the Built-in widgets for more information about which widgets are available and which arguments they accept.
Widgets inheriting from the Select widget¶
Widgets inheriting from the Select widget deal with choices. They
present the user with a list of options to choose from. The different widgets
present this choice differently; the Select widget itself uses a
<select> HTML list representation, while RadioSelect uses radio
buttons.
Select widgets are used by default on ChoiceField fields. The
choices displayed on the widget are inherited from the ChoiceField and
changing ChoiceField.choices will update Select.choices. For
example:
>>> from django import forms
>>> CHOICES = (('1', 'First',), ('2', 'Second',))
>>> choice_field = forms.ChoiceField(widget=forms.RadioSelect, choices=CHOICES)
>>> choice_field.choices
[('1', 'First'), ('2', 'Second')]
>>> choice_field.widget.choices
[('1', 'First'), ('2', 'Second')]
>>> choice_field.widget.choices = ()
>>> choice_field.choices = (('1', 'First and only',),)
>>> choice_field.widget.choices
[('1', 'First and only')]
Widgets which offer a choices attribute can however be used
with fields which are not based on choice – such as a CharField –
but it is recommended to use a ChoiceField-based field when the
choices are inherent to the model and not just the representational widget.
Customizing widget instances¶
When Django renders a widget as HTML, it only renders very minimal markup -
Django doesn’t add class names, or any other widget-specific attributes. This
means, for example, that all TextInput widgets will appear the same
on your Web pages.
There are two ways to customize widgets: per widget instance and per widget class.
Styling widget instances¶
If you want to make one widget instance look different from another, you will need to specify additional attributes at the time when the widget object is instantiated and assigned to a form field (and perhaps add some rules to your CSS files).
For example, take the following simple form:
from django import forms
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" required /></td></tr>
<tr><th>Url:</th><td><input type="url" name="url" required /></td></tr>
<tr><th>Comment:</th><td><input type="text" name="comment" required /></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. It is also possible to specify
the “type” attribute to take advantage of the new HTML5 input types. To do
this, you use the Widget.attrs argument when creating the widget:
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'}))
You can also modify a widget in the form definition:
class CommentForm(forms.Form):
name = forms.CharField()
url = forms.URLField()
comment = forms.CharField()
name.widget.attrs.update({'class': 'special'})
comment.widget.attrs.update(size='40')
Or if the field isn’t declared directly on the form (such as model form fields),
you can use the Form.fields attribute:
class CommentForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.fields['name'].widget.attrs.update({'class': 'special'})
self.fields['comment'].widget.attrs.update(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" required /></td></tr>
<tr><th>Url:</th><td><input type="url" name="url" required /></td></tr>
<tr><th>Comment:</th><td><input type="text" name="comment" size="40" required /></td></tr>
You can also set the HTML id using attrs. See
BoundField.id_for_label for an example.
Styling widget classes¶
With widgets, it is possible to add assets (css and javascript)
and more deeply customize their appearance and behavior.
In a nutshell, you will need to subclass the widget and either define a «Media» inner class or create a «media» property.
These methods involve somewhat advanced Python programming and are described in detail in the Form Assets topic guide.
Base widget classes¶
Base widget classes Widget and MultiWidget are subclassed by
all the built-in widgets and may serve as a
foundation for custom widgets.
Widget¶
-
class
Widget(attrs=None)[πηγή]¶ This abstract class cannot be rendered, but provides the basic attribute
attrs. You may also implement or override therender()method on custom widgets.-
attrs¶ A dictionary containing HTML attributes to be set on the rendered widget.
>>> from django import forms >>> name = forms.TextInput(attrs={'size': 10, 'title': 'Your name'}) >>> name.render('name', 'A name') '<input title="Your name" type="text" name="name" value="A name" size="10" />'
If you assign a value of
TrueorFalseto an attribute, it will be rendered as an HTML5 boolean attribute:>>> name = forms.TextInput(attrs={'required': True}) >>> name.render('name', 'A name') '<input name="name" type="text" value="A name" required />' >>> >>> name = forms.TextInput(attrs={'required': False}) >>> name.render('name', 'A name') '<input name="name" type="text" value="A name" />'
-
supports_microseconds¶ An attribute that defaults to
True. If set toFalse, the microseconds part ofdatetimeandtimevalues will be set to0.
-
format_value(value)[πηγή]¶ Cleans and returns a value for use in the widget template.
valueisn’t guaranteed to be valid input, therefore subclass implementations should program defensively.
-
get_context(name, value, attrs)[πηγή]¶ - New in Django 1.11.
Returns a dictionary of values to use when rendering the widget template. By default, the dictionary contains a single key,
'widget', which is a dictionary representation of the widget containing the following keys:'name': The name of the field from thenameargument.'is_hidden': A boolean indicating whether or not this widget is hidden.'required': A boolean indicating whether or not the field for this widget is required.'value': The value as returned byformat_value().'attrs': HTML attributes to be set on the rendered widget. The combination of theattrsattribute and theattrsargument.'template_name': The value ofself.template_name.
Widgetsubclasses can provide custom context values by overriding this method.
-
id_for_label(id_)[πηγή]¶ Returns the HTML ID attribute of this widget for use by a
<label>, given the ID of the field. ReturnsNoneif an ID isn’t available.This hook is necessary because some widgets have multiple HTML elements and, thus, multiple IDs. In that case, this method should return an ID value that corresponds to the first ID in the widget’s tags.
-
render(name, value, attrs=None, renderer=None)[πηγή]¶ Renders a widget to HTML using the given renderer. If
rendererisNone, the renderer from theFORM_RENDERERsetting is used.Changed in Django 1.11:The
rendererargument was added. Support for subclasses that don’t accept it will be removed in Django 2.1.
-
value_from_datadict(data, files, name)[πηγή]¶ Given a dictionary of data and this widget’s name, returns the value of this widget.
filesmay contain data coming fromrequest.FILES. ReturnsNoneif a value wasn’t provided. Note also thatvalue_from_datadictmay be called more than once during handling of form data, so if you customize it and add expensive processing, you should implement some caching mechanism yourself.
-
value_omitted_from_data(data, files, name)[πηγή]¶ Given
dataandfilesdictionaries and this widget’s name, returns whether or not there’s data or files for the widget.The method’s result affects whether or not a field in a model form falls back to its default.
Special cases are
CheckboxInput,CheckboxSelectMultiple, andSelectMultiple, which always returnFalsebecause an unchecked checkbox and unselected<select multiple>don’t appear in the data of an HTML form submission, so it’s unknown whether or not the user submitted a value.
-
use_required_attribute(initial)[πηγή]¶ Given a form field’s
initialvalue, returns whether or not the widget can be rendered with therequiredHTML attribute. Forms use this method along withField.requiredandForm.use_required_attributeto determine whether or not to display therequiredattribute for each field.By default, returns
Falsefor hidden widgets andTrueotherwise. Special cases areClearableFileInput, which returnsFalsewheninitialis not set, andCheckboxSelectMultiple, which always returnsFalsebecause browser validation would require all checkboxes to be checked instead of at least one.Override this method in custom widgets that aren’t compatible with browser validation. For example, a WSYSIWG text editor widget backed by a hidden
textareaelement may want to always returnFalseto avoid browser validation on the hidden field.
-
MultiWidget¶
-
class
MultiWidget(widgets, attrs=None)[πηγή]¶ A widget that is composed of multiple widgets.
MultiWidgetworks hand in hand with theMultiValueField.MultiWidgethas one required argument:-
widgets¶ An iterable containing the widgets needed.
And one required method:
-
decompress(value)[πηγή]¶ This method takes a single «compressed» value from the field and returns a list of «decompressed» values. The input value can be assumed valid, but not necessarily non-empty.
This method must be implemented by the subclass, and since the value may be empty, the implementation must be defensive.
The rationale behind «decompression» is that it is necessary to «split» the combined value of the form field into the values for each widget.
An example of this is how
SplitDateTimeWidgetturns adatetimevalue into a list with date and time split into two separate values:from django.forms import MultiWidget class SplitDateTimeWidget(MultiWidget): # ... def decompress(self, value): if value: return [value.date(), value.time().replace(microsecond=0)] return [None, None]
Πρακτική συμβουλή
Note that
MultiValueFieldhas a complementary methodcompress()with the opposite responsibility - to combine cleaned values of all member fields into one.
It provides some custom context:
-
get_context(name, value, attrs)[πηγή]¶ In addition to the
'widget'key described inWidget.get_context(),MultiValueWidgetadds awidget['subwidgets']key.These can be looped over in the widget template:
{% for subwidget in widget.subwidgets %} {% include widget.template_name with widget=subwidget %} {% endfor %}
Here’s an example widget which subclasses
MultiWidgetto display a date with the day, month, and year in different select boxes. This widget is intended to be used with aDateFieldrather than aMultiValueField, thus we have implementedvalue_from_datadict():from datetime import date from django.forms import widgets class DateSelectorWidget(widgets.MultiWidget): def __init__(self, attrs=None): # create choices for days, months, years # example below, the rest snipped for brevity. years = [(year, year) for year in (2011, 2012, 2013)] _widgets = ( widgets.Select(attrs=attrs, choices=days), widgets.Select(attrs=attrs, choices=months), widgets.Select(attrs=attrs, choices=years), ) super().__init__(_widgets, attrs) def decompress(self, value): if value: return [value.day, value.month, value.year] return [None, None, None] def value_from_datadict(self, data, files, name): datelist = [ widget.value_from_datadict(data, files, name + '_%s' % i) for i, widget in enumerate(self.widgets)] try: D = date( day=int(datelist[0]), month=int(datelist[1]), year=int(datelist[2]), ) except ValueError: return '' else: return str(D)
The constructor creates several
Selectwidgets in a tuple. Thesuperclass uses this tuple to setup the widget.The required method
decompress()breaks up adatetime.datevalue into the day, month, and year values corresponding to each widget. Note how the method handles the case wherevalueisNone.The default implementation of
value_from_datadict()returns a list of values corresponding to eachWidget. This is appropriate when using aMultiWidgetwith aMultiValueField, but since we want to use this widget with aDateFieldwhich takes a single value, we have overridden this method to combine the data of all the subwidgets into adatetime.date. The method extracts data from thePOSTdictionary and constructs and validates the date. If it is valid, we return the string, otherwise, we return an empty string which will causeform.is_validto returnFalse.-
Built-in widgets¶
Django provides a representation of all the basic HTML widgets, plus some
commonly used groups of widgets in the django.forms.widgets module,
including the input of text, various checkboxes
and selectors, uploading files,
and handling of multi-valued input.
Widgets handling input of text¶
These widgets make use of the HTML elements input and textarea.
TextInput¶
NumberInput¶
-
class
NumberInput[πηγή]¶ input_type:'number'template_name:'django/forms/widgets/number.html'- Renders as:
<input type="number" ...>
Beware that not all browsers support entering localized numbers in
numberinput types. Django itself avoids using them for fields having theirlocalizeproperty set toTrue.
EmailInput¶
URLInput¶
PasswordInput¶
-
class
PasswordInput[πηγή]¶ input_type:'password'template_name:'django/forms/widgets/password.html'- Renders as:
<input type="password" ...>
Takes one optional argument:
-
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).
DateInput¶
-
class
DateInput[πηγή]¶ input_type:'text'template_name:'django/forms/widgets/date.html'- Renders as:
<input type="text" ...>
Takes same arguments as
TextInput, with one more optional argument:-
format¶ The format in which this field’s initial value will be displayed.
If no
formatargument is provided, the default format is the first format found inDATE_INPUT_FORMATSand respects Format localization.
DateTimeInput¶
-
class
DateTimeInput[πηγή]¶ input_type:'text'template_name:'django/forms/widgets/datetime.html'- Renders as:
<input type="text" ...>
Takes same arguments as
TextInput, with one more optional argument:-
format¶ The format in which this field’s initial value will be displayed.
If no
formatargument is provided, the default format is the first format found inDATETIME_INPUT_FORMATSand respects Format localization.By default, the microseconds part of the time value is always set to
0. If microseconds are required, use a subclass with thesupports_microsecondsattribute set toTrue.
TimeInput¶
-
class
TimeInput[πηγή]¶ input_type:'text'template_name:'django/forms/widgets/time.html'- Renders as:
<input type="text" ...>
Takes same arguments as
TextInput, with one more optional argument:-
format¶ The format in which this field’s initial value will be displayed.
If no
formatargument is provided, the default format is the first format found inTIME_INPUT_FORMATSand respects Format localization.For the treatment of microseconds, see
DateTimeInput.
Selector and checkbox widgets¶
These widgets make use of the HTML elements <select>,
<input type="checkbox">, and <input type="radio">.
Widgets that render multiple choices have an option_template_name attribute
that specifies the template used to render each choice. For example, for the
Select widget, select_option.html renders the <option> for a
<select>.
CheckboxInput¶
-
class
CheckboxInput[πηγή]¶ input_type:'checkbox'template_name:'django/forms/widgets/checkbox.html'- Renders as:
<input type="checkbox" ...>
Takes one optional argument:
-
check_test¶ A callable that takes the value of the
CheckboxInputand returnsTrueif the checkbox should be checked for that value.
Select¶
NullBooleanSelect¶
SelectMultiple¶
RadioSelect¶
-
class
RadioSelect[πηγή]¶ template_name:'django/forms/widgets/radio.html'option_template_name:'django/forms/widgets/radio_option.html'
Similar to
Select, but rendered as a list of radio buttons within<li>tags:<ul> <li><input type="radio" name="..."></li> ... </ul>
For more granular control over the generated markup, you can loop over the radio buttons in the template. Assuming a form
myformwith a fieldbeatlesthat uses aRadioSelectas its widget:{% for radio in myform.beatles %} <div class="myradio"> {{ radio }} </div> {% endfor %}
This would generate the following HTML:
<div class="myradio"> <label for="id_beatles_0"><input id="id_beatles_0" name="beatles" type="radio" value="john" required /> John</label> </div> <div class="myradio"> <label for="id_beatles_1"><input id="id_beatles_1" name="beatles" type="radio" value="paul" required /> Paul</label> </div> <div class="myradio"> <label for="id_beatles_2"><input id="id_beatles_2" name="beatles" type="radio" value="george" required /> George</label> </div> <div class="myradio"> <label for="id_beatles_3"><input id="id_beatles_3" name="beatles" type="radio" value="ringo" required /> Ringo</label> </div>
That included the
<label>tags. To get more granular, you can use each radio button’stag,choice_labelandid_for_labelattributes. For example, this template…{% for radio in myform.beatles %} <label for="{{ radio.id_for_label }}"> {{ radio.choice_label }} <span class="radio">{{ radio.tag }}</span> </label> {% endfor %}
…will result in the following HTML:
<label for="id_beatles_0"> John <span class="radio"><input id="id_beatles_0" name="beatles" type="radio" value="john" required /></span> </label> <label for="id_beatles_1"> Paul <span class="radio"><input id="id_beatles_1" name="beatles" type="radio" value="paul" required /></span> </label> <label for="id_beatles_2"> George <span class="radio"><input id="id_beatles_2" name="beatles" type="radio" value="george" required /></span> </label> <label for="id_beatles_3"> Ringo <span class="radio"><input id="id_beatles_3" name="beatles" type="radio" value="ringo" required /></span> </label>
If you decide not to loop over the radio buttons – e.g., if your template simply includes
{{ myform.beatles }}– they’ll be output in a<ul>with<li>tags, as above.The outer
<ul>container receives theidattribute of the widget, if defined, orBoundField.auto_idotherwise.When looping over the radio buttons, the
labelandinputtags includeforandidattributes, respectively. Each radio button has anid_for_labelattribute to output the element’s ID.
CheckboxSelectMultiple¶
-
class
CheckboxSelectMultiple[πηγή]¶ template_name:'django/forms/widgets/checkbox_select.html'option_template_name:'django/forms/widgets/checkbox_option.html'
Similar to
SelectMultiple, but rendered as a list of checkboxes:<ul> <li><input type="checkbox" name="..." ></li> ... </ul>
The outer
<ul>container receives theidattribute of the widget, if defined, orBoundField.auto_idotherwise.
Like RadioSelect, you can loop over the individual checkboxes for the
widget’s choices. Unlike RadioSelect, the checkboxes won’t include the
required HTML attribute if the field is required because browser validation
would require all checkboxes to be checked instead of at least one.
When looping over the checkboxes, the label and input tags include
for and id attributes, respectively. Each checkbox has an
id_for_label attribute to output the element’s ID.
Composite widgets¶
SplitDateTimeWidget¶
-
class
SplitDateTimeWidget[πηγή]¶ template_name:'django/forms/widgets/splitdatetime.html'
Wrapper (using
MultiWidget) around two widgets:DateInputfor the date, andTimeInputfor the time. Must be used withSplitDateTimeFieldrather thanDateTimeField.SplitDateTimeWidgethas several optional arguments:-
date_format¶ Similar to
DateInput.format
-
time_format¶ Similar to
TimeInput.format
-
date_attrs¶
-
time_attrs¶ - New in Django 2.0.
Similar to
Widget.attrs. A dictionary containing HTML attributes to be set on the renderedDateInputandTimeInputwidgets, respectively. If these attributes aren’t set,Widget.attrsis used instead.
SelectDateWidget¶
-
class
SelectDateWidget[πηγή]¶ template_name:'django/forms/widgets/select_date.html'
Wrapper around three
Selectwidgets: one each for month, day, and year.Takes several optional arguments:
-
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.
-
months¶ An optional dict of months to use in the «months» select box.
The keys of the dict correspond to the month number (1-indexed) and the values are the displayed months:
MONTHS = { 1:_('jan'), 2:_('feb'), 3:_('mar'), 4:_('apr'), 5:_('may'), 6:_('jun'), 7:_('jul'), 8:_('aug'), 9:_('sep'), 10:_('oct'), 11:_('nov'), 12:_('dec') }
-
empty_label¶ If the
DateFieldis not required,SelectDateWidgetwill have an empty choice at the top of the list (which is---by default). You can change the text of this label with theempty_labelattribute.empty_labelcan be astring,list, ortuple. When a string is used, all select boxes will each have an empty choice with this label. Ifempty_labelis alistortupleof 3 string elements, the select boxes will have their own custom label. The labels should be in this order('year_label', 'month_label', 'day_label').# A custom empty label with string field1 = forms.DateField(widget=SelectDateWidget(empty_label="Nothing")) # A custom empty label with tuple field1 = forms.DateField( widget=SelectDateWidget( empty_label=("Choose Year", "Choose Month", "Choose Day"), ), )