小部件P

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'.

小技巧

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 widgetsP

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 widgetsP

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` widgetP

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 instancesP

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 instancesP

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.

Base widget classesP

Base widget classes Widget and MultiWidget are subclassed by all the built-in widgets and may serve as a foundation for custom widgets.

`Widget`P

class Widget(attrs=None)[源代码]P

This abstract class cannot be rendered, but provides the basic attribute attrs. You may also implement or override the render() method on custom widgets.

attrsP

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 True or False to 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_microsecondsP: An attribute that defaults to True. If set to False, the microseconds part of datetime and time values will be set to 0.

format_value(value)[源代码]P: Cleans and returns a value for use in the widget template. value isn't guaranteed to be valid input, therefore subclass implementations should program defensively.

get_context(name, value, attrs)[源代码]P

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 the name argument.
'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 by format_value().
'attrs': HTML attributes to be set on the rendered widget. The combination of the attrs attribute and the attrs argument.
'template_name': The value of self.template_name.

Widget subclasses can provide custom context values by overriding this method.

id_for_label(id_)[源代码]P

Returns the HTML ID attribute of this widget for use by a <label>, given the ID of the field. Returns None if 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)[源代码]P: Renders a widget to HTML using the given renderer. If renderer is None, the renderer from the FORM_RENDERER setting is used.

value_from_datadict(data, files, name)[源代码]P: Given a dictionary of data and this widget's name, returns the value of this widget. files may contain data coming from request.FILES. Returns None if a value wasn't provided. Note also that value_from_datadict may 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)[源代码]P

Given data and files dictionaries 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, and SelectMultiple, which always return False because 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)[源代码]P

Given a form field's initial value, returns whether or not the widget can be rendered with the required HTML attribute. Forms use this method along with Field.required and Form.use_required_attribute to determine whether or not to display the required attribute for each field.

By default, returns False for hidden widgets and True otherwise. Special cases are ClearableFileInput, which returns False when initial is not set, and CheckboxSelectMultiple, which always returns False because 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 textarea element may want to always return False to avoid browser validation on the hidden field.

`MultiWidget`P

class MultiWidget(widgets, attrs=None)[源代码]P

A widget that is composed of multiple widgets. MultiWidget works hand in hand with the MultiValueField.

MultiWidget has one required argument:

widgetsP: An iterable containing the widgets needed.

And one required method:

decompress(value)[源代码]P

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 SplitDateTimeWidget turns a datetime value 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()]
        return [None, None]

小技巧

Note that MultiValueField has a complementary method compress() with the opposite responsibility - to combine cleaned values of all member fields into one.

It provides some custom context:

get_context(name, value, attrs)[源代码]P

In addition to the 'widget' key described in Widget.get_context(), MultiValueWidget adds a widget['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 MultiWidget to display a date with the day, month, and year in different select boxes. This widget is intended to be used with a DateField rather than a MultiValueField, thus we have implemented value_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 Select widgets in a tuple. The super class uses this tuple to setup the widget.

The required method decompress() breaks up a datetime.date value into the day, month, and year values corresponding to each widget. Note how the method handles the case where value is None.

The default implementation of value_from_datadict() returns a list of values corresponding to each Widget. This is appropriate when using a MultiWidget with a MultiValueField, but since we want to use this widget with a DateField which takes a single value, we have overridden this method to combine the data of all the subwidgets into a datetime.date. The method extracts data from the POST dictionary and constructs and validates the date. If it is valid, we return the string, otherwise, we return an empty string which will cause form.is_valid to return False.

Built-in widgetsP

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 textP

These widgets make use of the HTML elements input and textarea.

`TextInput`P

class TextInput[源代码]P

input_type: 'text'
template_name: 'django/forms/widgets/text.html'
Renders as: <input type="text" ...>

`NumberInput`P

class NumberInput[源代码]P

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 number input types. Django itself avoids using them for fields having their localize property set to True.

`EmailInput`P

class EmailInput[源代码]P

input_type: 'email'
template_name: 'django/forms/widgets/email.html'
Renders as: <input type="email" ...>

`URLInput`P

class URLInput[源代码]P

input_type: 'url'
template_name: 'django/forms/widgets/url.html'
Renders as: <input type="url" ...>

`PasswordInput`P

class PasswordInput[源代码]P

input_type: 'password'
template_name: 'django/forms/widgets/password.html'
Renders as: <input type="password" ...>

Takes one optional argument:

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

`HiddenInput`P

class HiddenInput[源代码]P

input_type: 'hidden'
template_name: 'django/forms/widgets/hidden.html'
Renders as: <input type="hidden" ...>

Note that there also is a MultipleHiddenInput widget that encapsulates a set of hidden input elements.

`DateInput`P

class DateInput[源代码]P

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:

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

If no format argument is provided, the default format is the first format found in DATE_INPUT_FORMATS and respects Format localization.

`DateTimeInput`P

class DateTimeInput[源代码]P

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:

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

If no format argument is provided, the default format is the first format found in DATETIME_INPUT_FORMATS and 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 the supports_microseconds attribute set to True.

`TimeInput`P

class TimeInput[源代码]P

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:

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

If no format argument is provided, the default format is the first format found in TIME_INPUT_FORMATS and respects Format localization.

For the treatment of microseconds, see DateTimeInput.

`Textarea`P

class Textarea[源代码]P

template_name: 'django/forms/widgets/textarea.html'
Renders as: <textarea>...</textarea>

Selector and checkbox widgetsP

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`P

class CheckboxInput[源代码]P

input_type: 'checkbox'
template_name: 'django/forms/widgets/checkbox.html'
Renders as: <input type="checkbox" ...>

Takes one optional argument:

check_testP: A callable that takes the value of the CheckboxInput and returns True if the checkbox should be checked for that value.

`Select`P

class Select[源代码]P

template_name: 'django/forms/widgets/select.html'
option_template_name: 'django/forms/widgets/select_option.html'
Renders as: <select><option ...>...</select>

choicesP: This attribute is optional when the form field does not have a choices attribute. If it does, it will override anything you set here when the attribute is updated on the Field.

`NullBooleanSelect`P

class NullBooleanSelect[源代码]P

template_name: 'django/forms/widgets/select.html'
option_template_name: 'django/forms/widgets/select_option.html'

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

`SelectMultiple`P

class SelectMultiple[源代码]P

template_name: 'django/forms/widgets/select.html'
option_template_name: 'django/forms/widgets/select_option.html'

Similar to Select, but allows multiple selection: <select multiple>...</select>

`RadioSelect`P

class RadioSelect[源代码]P

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 myform with a field beatles that uses a RadioSelect as 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's tag, choice_label and id_for_label attributes. 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 the id attribute of the widget, if defined, or BoundField.auto_id otherwise.

When looping over the radio buttons, the label and input tags include for and id attributes, respectively. Each radio button has an id_for_label attribute to output the element's ID.

`CheckboxSelectMultiple`P

class CheckboxSelectMultiple[源代码]P

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 the id attribute of the widget, if defined, or BoundField.auto_id otherwise.

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.

File upload widgetsP

`FileInput`P

class FileInput[源代码]P

template_name: 'django/forms/widgets/file.html'
Renders as: <input type="file" ...>

`ClearableFileInput`P

class ClearableFileInput[源代码]P

template_name: 'django/forms/widgets/clearable_file_input.html'
Renders as: <input type="file" ...> with an additional checkbox input to clear the field's value, if the field is not required and has initial data.

Composite widgetsP

`MultipleHiddenInput`P

class MultipleHiddenInput[源代码]P

template_name: 'django/forms/widgets/multiple_hidden.html'
Renders as: multiple <input type="hidden" ...> tags

A widget that handles multiple hidden widgets for fields that have a list of values.

choicesP: This attribute is optional when the form field does not have a choices attribute. If it does, it will override anything you set here when the attribute is updated on the Field.

`SplitDateTimeWidget`P

class SplitDateTimeWidget[源代码]P

template_name: 'django/forms/widgets/splitdatetime.html'

Wrapper (using MultiWidget) around two widgets: DateInput for the date, and TimeInput for the time. Must be used with SplitDateTimeField rather than DateTimeField.

SplitDateTimeWidget has several optional arguments:

date_formatP: Similar to DateInput.format

time_formatP: Similar to TimeInput.format

date_attrsP

time_attrsP: Similar to Widget.attrs. A dictionary containing HTML attributes to be set on the rendered DateInput and TimeInput widgets, respectively. If these attributes aren't set, Widget.attrs is used instead.

`SplitHiddenDateTimeWidget`P

class SplitHiddenDateTimeWidget[源代码]P

template_name: 'django/forms/widgets/splithiddendatetime.html'

Similar to SplitDateTimeWidget, but uses HiddenInput for both date and time.

`SelectDateWidget`P

class SelectDateWidget[源代码]P

template_name: 'django/forms/widgets/select_date.html'

Wrapper around three Select widgets: one each for month, day, and year.

Takes several optional arguments:

yearsP: 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.

monthsP

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_labelP

If the DateField is not required, SelectDateWidget will have an empty choice at the top of the list (which is --- by default). You can change the text of this label with the empty_label attribute. empty_label can be a string, list, or tuple. When a string is used, all select boxes will each have an empty choice with this label. If empty_label is a list or tuple of 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"),
    ),
)

Django 2.2.5.dev20190823064900 文档

小部件P

Specifying widgetsP

Setting arguments for widgetsP

Widgets inheriting from the Select widgetP

Customizing widget instancesP

Styling widget instancesP

Styling widget classesP

Base widget classesP

WidgetP

MultiWidgetP

Built-in widgetsP

Widgets handling input of textP

TextInputP

NumberInputP

EmailInputP

URLInputP

PasswordInputP

HiddenInputP

DateInputP

DateTimeInputP

TimeInputP

TextareaP

Selector and checkbox widgetsP

CheckboxInputP

SelectP

NullBooleanSelectP

SelectMultipleP

RadioSelectP

CheckboxSelectMultipleP

File upload widgetsP

FileInputP

ClearableFileInputP

Composite widgetsP

MultipleHiddenInputP

SplitDateTimeWidgetP

SplitHiddenDateTimeWidgetP

SelectDateWidgetP

Last update:

Widgets inheriting from the `Select` widgetP

`Widget`P

`MultiWidget`P

`TextInput`P

`NumberInput`P

`EmailInput`P

`URLInput`P

`PasswordInput`P

`HiddenInput`P

`DateInput`P

`DateTimeInput`P

`TimeInput`P

`Textarea`P

`CheckboxInput`P

`Select`P

`NullBooleanSelect`P

`SelectMultiple`P

`RadioSelect`P

`CheckboxSelectMultiple`P

`FileInput`P

`ClearableFileInput`P

`MultipleHiddenInput`P

`SplitDateTimeWidget`P

`SplitHiddenDateTimeWidget`P

`SelectDateWidget`P