Form fields

class Field(**kwargs)

When you create a Form class, the most important part is defining the fields of the form. Each field has custom validation logic, along with a few other hooks.

Field.clean(value)

Although the primary way you’ll use Field classes is in Form classes, you can also instantiate them and use them directly to get a better idea of how they work. Each Field instance has a clean() method, which takes a single argument and either raises a django.core.exceptions.ValidationError exception or returns the clean value:

>>> from django import forms
>>> f = forms.EmailField()
>>> f.clean("foo@example.com")
'foo@example.com'
>>> f.clean("invalid email address")
Traceback (most recent call last):
...
ValidationError: ['Enter a valid email address.']

Core field arguments

Each Field class constructor takes at least these arguments. Some Field classes take additional, field-specific arguments, but the following should always be accepted:

required

Field.required

By default, each Field class assumes the value is required, so if you pass an empty value – either None or the empty string ("") – then clean() will raise a ValidationError exception:

>>> from django import forms
>>> f = forms.CharField()
>>> f.clean("foo")
'foo'
>>> f.clean("")
Traceback (most recent call last):
...
ValidationError: ['This field is required.']
>>> f.clean(None)
Traceback (most recent call last):
...
ValidationError: ['This field is required.']
>>> f.clean(" ")
' '
>>> f.clean(0)
'0'
>>> f.clean(True)
'True'
>>> f.clean(False)
'False'

To specify that a field is not required, pass required=False to the Field constructor:

>>> f = forms.CharField(required=False)
>>> f.clean("foo")
'foo'
>>> f.clean("")
''
>>> f.clean(None)
''
>>> f.clean(0)
'0'
>>> f.clean(True)
'True'
>>> f.clean(False)
'False'

If a Field has required=False and you pass clean() an empty value, then clean() will return a normalized empty value rather than raising ValidationError. For CharField, this will return empty_value which defaults to an empty string. For other Field classes, it might be None. (This varies from field to field.)

Widgets of required form fields have the required HTML attribute. Set the Form.use_required_attribute attribute to False to disable it. The required attribute isn’t included on forms of formsets because the browser validation may not be correct when adding and deleting formsets.

label

Field.label

The label argument lets you specify the “human-friendly” label for this field. This is used when the Field is displayed in a Form.

As explained in “Outputting forms as HTML” above, the default label for a Field is generated from the field name by converting all underscores to spaces and upper-casing the first letter. Specify label if that default behavior doesn’t result in an adequate label.

Here’s a full example Form that implements label for two of its fields. We’ve specified auto_id=False to simplify the output:

>>> from django import forms
>>> class CommentForm(forms.Form):
...     name = forms.CharField(label="Your name")
...     url = forms.URLField(label="Your website", required=False)
...     comment = forms.CharField()
...
>>> f = CommentForm(auto_id=False)
>>> print(f)
<tr><th>Your name:</th><td><input type="text" name="name" required></td></tr>
<tr><th>Your website:</th><td><input type="url" name="url"></td></tr>
<tr><th>Comment:</th><td><input type="text" name="comment" required></td></tr>

label_suffix

Field.label_suffix

The label_suffix argument lets you override the form’s label_suffix on a per-field basis:

>>> class ContactForm(forms.Form):
...     age = forms.IntegerField()
...     nationality = forms.CharField()
...     captcha_answer = forms.IntegerField(label="2 + 2", label_suffix=" =")
...
>>> f = ContactForm(label_suffix="?")
>>> print(f.as_p())
<p><label for="id_age">Age?</label> <input id="id_age" name="age" type="number" required></p>
<p><label for="id_nationality">Nationality?</label> <input id="id_nationality" name="nationality" type="text" required></p>
<p><label for="id_captcha_answer">2 + 2 =</label> <input id="id_captcha_answer" name="captcha_answer" type="number" required></p>

initial

Field.initial

The initial argument lets you specify the initial value to use when rendering this Field in an unbound Form.

To specify dynamic initial data, see the Form.initial parameter.

The use-case for this is when you want to display an “empty” form in which a field is initialized to a particular value. For example:

>>> from django import forms
>>> class CommentForm(forms.Form):
...     name = forms.CharField(initial="Your name")
...     url = forms.URLField(initial="http://")
...     comment = forms.CharField()
...
>>> f = CommentForm(auto_id=False)
>>> print(f)
<tr><th>Name:</th><td><input type="text" name="name" value="Your name" required></td></tr>
<tr><th>Url:</th><td><input type="url" name="url" value="http://" required></td></tr>
<tr><th>Comment:</th><td><input type="text" name="comment" required></td></tr>

You may be thinking, why not just pass a dictionary of the initial values as data when displaying the form? Well, if you do that, you’ll trigger validation, and the HTML output will include any validation errors:

>>> class CommentForm(forms.Form):
...     name = forms.CharField()
...     url = forms.URLField()
...     comment = forms.CharField()
...
>>> default_data = {"name": "Your name", "url": "http://"}
>>> f = CommentForm(default_data, auto_id=False)
>>> print(f)
<tr><th>Name:</th><td><input type="text" name="name" value="Your name" required></td></tr>
<tr><th>Url:</th><td><ul class="errorlist"><li>Enter a valid URL.</li></ul><input type="url" name="url" value="http://" required></td></tr>
<tr><th>Comment:</th><td><ul class="errorlist"><li>This field is required.</li></ul><input type="text" name="comment" required></td></tr>

This is why initial values are only displayed for unbound forms. For bound forms, the HTML output will use the bound data.

Also note that initial values are not used as “fallback” data in validation if a particular field’s value is not given. initial values are only intended for initial form display:

>>> class CommentForm(forms.Form):
...     name = forms.CharField(initial="Your name")
...     url = forms.URLField(initial="http://")
...     comment = forms.CharField()
...
>>> data = {"name": "", "url": "", "comment": "Foo"}
>>> f = CommentForm(data)
>>> f.is_valid()
False
# The form does *not* fall back to using the initial values.
>>> f.errors
{'url': ['This field is required.'], 'name': ['This field is required.']}

Instead of a constant, you can also pass any callable:

>>> import datetime
>>> class DateForm(forms.Form):
...     day = forms.DateField(initial=datetime.date.today)
...
>>> print(DateForm())
<tr><th>Day:</th><td><input type="text" name="day" value="12/23/2008" required><td></tr>

The callable will be evaluated only when the unbound form is displayed, not when it is defined.

widget

Field.widget

The widget argument lets you specify a Widget class to use when rendering this Field. See Widgets for more information.

help_text

Field.help_text

The help_text argument lets you specify descriptive text for this Field. If you provide help_text, it will be displayed next to the Field when the Field is rendered by one of the convenience Form methods (e.g., as_ul()).

Like the model field’s help_text, this value isn’t HTML-escaped in automatically-generated forms.

Here’s a full example Form that implements help_text for two of its fields. We’ve specified auto_id=False to simplify the output:

>>> from django import forms
>>> class HelpTextContactForm(forms.Form):
...     subject = forms.CharField(max_length=100, help_text="100 characters max.")
...     message = forms.CharField()
...     sender = forms.EmailField(help_text="A valid email address, please.")
...     cc_myself = forms.BooleanField(required=False)
...
>>> f = HelpTextContactForm(auto_id=False)
>>> print(f.as_table())
<tr><th>Subject:</th><td><input type="text" name="subject" maxlength="100" required><br><span class="helptext">100 characters max.</span></td></tr>
<tr><th>Message:</th><td><input type="text" name="message" required></td></tr>
<tr><th>Sender:</th><td><input type="email" name="sender" required><br>A valid email address, please.</td></tr>
<tr><th>Cc myself:</th><td><input type="checkbox" name="cc_myself"></td></tr>
>>> print(f.as_ul())
<li>Subject: <input type="text" name="subject" maxlength="100" required> <span class="helptext">100 characters max.</span></li>
<li>Message: <input type="text" name="message" required></li>
<li>Sender: <input type="email" name="sender" required> A valid email address, please.</li>
<li>Cc myself: <input type="checkbox" name="cc_myself"></li>
>>> print(f.as_p())
<p>Subject: <input type="text" name="subject" maxlength="100" required> <span class="helptext">100 characters max.</span></p>
<p>Message: <input type="text" name="message" required></p>
<p>Sender: <input type="email" name="sender" required> A valid email address, please.</p>
<p>Cc myself: <input type="checkbox" name="cc_myself"></p>

error_messages

Field.error_messages

The error_messages argument lets you override the default messages that the field will raise. Pass in a dictionary with keys matching the error messages you want to override. For example, here is the default error message:

>>> from django import forms
>>> generic = forms.CharField()
>>> generic.clean("")
Traceback (most recent call last):
  ...
ValidationError: ['This field is required.']

And here is a custom error message:

>>> name = forms.CharField(error_messages={"required": "Please enter your name"})
>>> name.clean("")
Traceback (most recent call last):
  ...
ValidationError: ['Please enter your name']

In the built-in Field classes section below, each Field defines the error message keys it uses.

validators

Field.validators

The validators argument lets you provide a list of validation functions for this field.

See the validators documentation for more information.

localize

Field.localize

The localize argument enables the localization of form data input, as well as the rendered output.

See the format localization documentation for more information.

disabled

Field.disabled

The disabled boolean argument, when set to True, disables a form field using the disabled HTML attribute so that it won’t be editable by users. Even if a user tampers with the field’s value submitted to the server, it will be ignored in favor of the value from the form’s initial data.

Checking if the field data has changed

has_changed()

Field.has_changed()

The has_changed() method is used to determine if the field value has changed from the initial value. Returns True or False.

See the Form.has_changed() documentation for more information.

Built-in Field classes

Naturally, the forms library comes with a set of Field classes that represent common validation needs. This section documents each built-in field.

For each field, we describe the default widget used if you don’t specify widget. We also specify the value returned when you provide an empty value (see the section on required above to understand what that means).

BooleanField

class BooleanField(**kwargs)

• Default widget: CheckboxInput
• Empty value: False
• Normalizes to: A Python True or False value.
• Validates that the value is True (e.g. the check box is checked) if the field has required=True.
• Error message keys: required

Note

Since all Field subclasses have required=True by default, the validation condition here is important. If you want to include a boolean in your form that can be either True or False (e.g. a checked or unchecked checkbox), you must remember to pass in required=False when creating the BooleanField.

CharField

class CharField(**kwargs)

• Default widget: TextInput
• Empty value: Whatever you’ve given as empty_value.
• Normalizes to: A string.
• Uses MaxLengthValidator and MinLengthValidator if max_length and min_length are provided. Otherwise, all inputs are valid.
• Error message keys: required, max_length, min_length

Has the following optional arguments for validation:

• max_length

• min_length

  If provided, these arguments ensure that the string is at most or at least the given length.

• strip

  If True (default), the value will be stripped of leading and trailing whitespace.

• empty_value

  The value to use to represent “empty”. Defaults to an empty string.

ChoiceField

class ChoiceField(**kwargs)

• Default widget: Select
• Empty value: '' (an empty string)
• Normalizes to: A string.
• Validates that the given value exists in the list of choices.
• Error message keys: required, invalid_choice

The invalid_choice error message may contain %(value)s, which will be replaced with the selected choice.

Takes one extra argument:

• choices

  Either an iterable of 2-tuples to use as choices for this field, enumeration choices, or a callable that returns such an iterable. This argument accepts the same formats as the choices argument to a model field. See the model field reference documentation on choices for more details. If the argument is a callable, it is evaluated each time the field’s form is initialized, in addition to during rendering. Defaults to an empty list.

Choice type

This field normalizes choices to strings, so if choices are required in other data types, such as integers or booleans, consider using TypedChoiceField instead.

DateField

class DateField(**kwargs)

• Default widget: DateInput
• Empty value: None
• Normalizes to: A Python datetime.date object.
• Validates that the given value is either a datetime.date, datetime.datetime or string formatted in a particular date format.
• Error message keys: required, invalid

Takes one optional argument:

• input_formats

  An iterable of formats used to attempt to convert a string to a valid datetime.date object.

If no input_formats argument is provided, the default input formats are taken from DATE_INPUT_FORMATS if USE_L10N is False, or from the active locale format DATE_INPUT_FORMATS key if localization is enabled. See also format localization.

DateTimeField

class DateTimeField(**kwargs)

• Default widget: DateTimeInput
• Empty value: None
• Normalizes to: A Python datetime.datetime object.
• Validates that the given value is either a datetime.datetime, datetime.date or string formatted in a particular datetime format.
• Error message keys: required, invalid

Takes one optional argument:

• input_formats

  An iterable of formats used to attempt to convert a string to a valid datetime.datetime object, in addition to ISO 8601 formats.

The field always accepts strings in ISO 8601 formatted dates or similar recognized by parse_datetime(). Some examples are:

• '2006-10-25 14:30:59'
• '2006-10-25T14:30:59'
• '2006-10-25 14:30'
• '2006-10-25T14:30'
• '2006-10-25T14:30Z'
• '2006-10-25T14:30+02:00'
• '2006-10-25'

If no input_formats argument is provided, the default input formats are taken from DATETIME_INPUT_FORMATS and DATE_INPUT_FORMATS if USE_L10N is False, or from the active locale format DATETIME_INPUT_FORMATS and DATE_INPUT_FORMATS keys if localization is enabled. See also format localization.

DecimalField

class DecimalField(**kwargs)

• Default widget: NumberInput when Field.localize is False, else TextInput.
• Empty value: None
• Normalizes to: A Python decimal.
• Validates that the given value is a decimal. Uses MaxValueValidator and MinValueValidator if max_value and min_value are provided. Uses StepValueValidator if step_size is provided. Leading and trailing whitespace is ignored.
• Error message keys: required, invalid, max_value, min_value, max_digits, max_decimal_places, max_whole_digits, step_size.

The max_value and min_value error messages may contain %(limit_value)s, which will be substituted by the appropriate limit. Similarly, the max_digits, max_decimal_places and max_whole_digits error messages may contain %(max)s.

Takes five optional arguments:

• max_value

• min_value

  These control the range of values permitted in the field, and should be given as decimal.Decimal values.

• max_digits

  The maximum number of digits (those before the decimal point plus those after the decimal point, with leading zeros stripped) permitted in the value.

• decimal_places

  The maximum number of decimal places permitted.

• step_size

  Limit valid inputs to an integral multiple of step_size.

Changed in Django 4.1:

The step_size argument was added.

DurationField

class DurationField(**kwargs)

• Default widget: TextInput
• Empty value: None
• Normalizes to: A Python timedelta.
• Validates that the given value is a string which can be converted into a timedelta. The value must be between datetime.timedelta.min and datetime.timedelta.max.
• Error message keys: required, invalid, overflow.

Accepts any format understood by parse_duration().

EmailField

class EmailField(**kwargs)

• Default widget: EmailInput
• Empty value: Whatever you’ve given as empty_value.
• Normalizes to: A string.
• Uses EmailValidator to validate that the given value is a valid email address, using a moderately complex regular expression.
• Error message keys: required, invalid

Has the optional arguments max_length, min_length, and empty_value which work just as they do for CharField. The max_length argument defaults to 320 (see RFC 3696#section-3).

Changed in Django 3.2.20:

The default value for max_length was changed to 320 characters.

FileField

class FileField(**kwargs)

• Default widget: ClearableFileInput
• Empty value: None
• Normalizes to: An UploadedFile object that wraps the file content and file name into a single object.
• Can validate that non-empty file data has been bound to the form.
• Error message keys: required, invalid, missing, empty, max_length

Has the optional arguments for validation: max_length and allow_empty_file. If provided, these ensure that the file name is at most the given length, and that validation will succeed even if the file content is empty.

To learn more about the UploadedFile object, see the file uploads documentation.

When you use a FileField in a form, you must also remember to bind the file data to the form.

The max_length error refers to the length of the filename. In the error message for that key, %(max)d will be replaced with the maximum filename length and %(length)d will be replaced with the current filename length.

FilePathField

class FilePathField(**kwargs)

• Default widget: Select
• Empty value: '' (an empty string)
• Normalizes to: A string.
• Validates that the selected choice exists in the list of choices.
• Error message keys: required, invalid_choice

The field allows choosing from files inside a certain directory. It takes five extra arguments; only path is required:

• path

  The absolute path to the directory whose contents you want listed. This directory must exist.

• recursive

  If False (the default) only the direct contents of path will be offered as choices. If True, the directory will be descended into recursively and all descendants will be listed as choices.

• match

  A regular expression pattern; only files with names matching this expression will be allowed as choices.

• allow_files

  Optional. Either True or False. Default is True. Specifies whether files in the specified location should be included. Either this or allow_folders must be True.

• allow_folders

  Optional. Either True or False. Default is False. Specifies whether folders in the specified location should be included. Either this or allow_files must be True.

FloatField

class FloatField(**kwargs)

• Default widget: NumberInput when Field.localize is False, else TextInput.
• Empty value: None
• Normalizes to: A Python float.
• Validates that the given value is a float. Uses MaxValueValidator and MinValueValidator if max_value and min_value are provided. Uses StepValueValidator if step_size is provided. Leading and trailing whitespace is allowed, as in Python’s float() function.
• Error message keys: required, invalid, max_value, min_value, step_size.

Takes three optional arguments:

• max_value

• min_value

  These control the range of values permitted in the field.

• step_size

  New in Django 4.1.

  Limit valid inputs to an integral multiple of step_size.

GenericIPAddressField

class GenericIPAddressField(**kwargs)

A field containing either an IPv4 or an IPv6 address.

• Default widget: TextInput
• Empty value: '' (an empty string)
• Normalizes to: A string. IPv6 addresses are normalized as described below.
• Validates that the given value is a valid IP address.
• Error message keys: required, invalid

The IPv6 address normalization follows RFC 4291#section-2.2 section 2.2, including using the IPv4 format suggested in paragraph 3 of that section, like ::ffff:192.0.2.0. For example, 2001:0::0:01 would be normalized to 2001::1, and ::ffff:0a0a:0a0a to ::ffff:10.10.10.10. All characters are converted to lowercase.

Takes two optional arguments:

• protocol

  Limits valid inputs to the specified protocol. Accepted values are both (default), IPv4 or IPv6. Matching is case insensitive.

• unpack_ipv4

  Unpacks IPv4 mapped addresses like ::ffff:192.0.2.1. If this option is enabled that address would be unpacked to 192.0.2.1. Default is disabled. Can only be used when protocol is set to 'both'.

ImageField

class ImageField(**kwargs)

• Default widget: ClearableFileInput
• Empty value: None
• Normalizes to: An UploadedFile object that wraps the file content and file name into a single object.
• Validates that file data has been bound to the form. Also uses FileExtensionValidator to validate that the file extension is supported by Pillow.
• Error message keys: required, invalid, missing, empty, invalid_image

Using an ImageField requires that Pillow is installed with support for the image formats you use. If you encounter a corrupt image error when you upload an image, it usually means that Pillow doesn’t understand its format. To fix this, install the appropriate library and reinstall Pillow.

When you use an ImageField on a form, you must also remember to bind the file data to the form.

After the field has been cleaned and validated, the UploadedFile object will have an additional image attribute containing the Pillow Image instance used to check if the file was a valid image. Pillow closes the underlying file descriptor after verifying an image, so while non-image data attributes, such as format, height, and width, are available, methods that access the underlying image data, such as getdata() or getpixel(), cannot be used without reopening the file. For example:

>>> from PIL import Image
>>> from django import forms
>>> from django.core.files.uploadedfile import SimpleUploadedFile
>>> class ImageForm(forms.Form):
...     img = forms.ImageField()
...
>>> file_data = {"img": SimpleUploadedFile("test.png", b"file data")}
>>> form = ImageForm({}, file_data)
# Pillow closes the underlying file descriptor.
>>> form.is_valid()
True
>>> image_field = form.cleaned_data["img"]
>>> image_field.image
<PIL.PngImagePlugin.PngImageFile image mode=RGBA size=191x287 at 0x7F5985045C18>
>>> image_field.image.width
191
>>> image_field.image.height
287
>>> image_field.image.format
'PNG'
>>> image_field.image.getdata()
# Raises AttributeError: 'NoneType' object has no attribute 'seek'.
>>> image = Image.open(image_field)
>>> image.getdata()
<ImagingCore object at 0x7f5984f874b0>

Additionally, UploadedFile.content_type will be updated with the image’s content type if Pillow can determine it, otherwise it will be set to None.

IntegerField

class IntegerField(**kwargs)

• Default widget: NumberInput when Field.localize is False, else TextInput.
• Empty value: None
• Normalizes to: A Python integer.
• Validates that the given value is an integer. Uses MaxValueValidator and MinValueValidator if max_value and min_value are provided. Uses StepValueValidator if step_size is provided. Leading and trailing whitespace is allowed, as in Python’s int() function.
• Error message keys: required, invalid, max_value, min_value, step_size

The max_value, min_value and step_size error messages may contain %(limit_value)s, which will be substituted by the appropriate limit.

Takes three optional arguments for validation:

• max_value

• min_value

  These control the range of values permitted in the field.

• step_size

  New in Django 4.1.

  Limit valid inputs to an integral multiple of step_size.

JSONField

class JSONField(encoder=None, decoder=None, **kwargs)

A field which accepts JSON encoded data for a JSONField.

• Default widget: Textarea
• Empty value: None
• Normalizes to: A Python representation of the JSON value (usually as a dict, list, or None), depending on JSONField.decoder.
• Validates that the given value is a valid JSON.
• Error message keys: required, invalid

Takes two optional arguments:

• encoder

  A json.JSONEncoder subclass to serialize data types not supported by the standard JSON serializer (e.g. datetime.datetime or UUID). For example, you can use the DjangoJSONEncoder class.

  Defaults to json.JSONEncoder.

• decoder

  A json.JSONDecoder subclass to deserialize the input. Your deserialization may need to account for the fact that you can’t be certain of the input type. For example, you run the risk of returning a datetime that was actually a string that just happened to be in the same format chosen for datetimes.

  The decoder can be used to validate the input. If json.JSONDecodeError is raised during the deserialization, a ValidationError will be raised.

  Defaults to json.JSONDecoder.

Note

If you use a ModelForm, the encoder and decoder from JSONField will be used.

User friendly forms

JSONField is not particularly user friendly in most cases. However, it is a useful way to format data from a client-side widget for submission to the server.

MultipleChoiceField

class MultipleChoiceField(**kwargs)

• Default widget: SelectMultiple
• Empty value: [] (an empty list)
• Normalizes to: A list of strings.
• Validates that every value in the given list of values exists in the list of choices.
• Error message keys: required, invalid_choice, invalid_list

The invalid_choice error message may contain %(value)s, which will be replaced with the selected choice.

Takes one extra required argument, choices, as for ChoiceField.

NullBooleanField

class NullBooleanField(**kwargs)

• Default widget: NullBooleanSelect
• Empty value: None
• Normalizes to: A Python True, False or None value.
• Validates nothing (i.e., it never raises a ValidationError).

NullBooleanField may be used with widgets such as Select or RadioSelect by providing the widget choices:

NullBooleanField(
    widget=Select(
        choices=[
            ("", "Unknown"),
            (True, "Yes"),
            (False, "No"),
        ]
    )
)

RegexField

class RegexField(**kwargs)

• Default widget: TextInput
• Empty value: Whatever you’ve given as empty_value.
• Normalizes to: A string.
• Uses RegexValidator to validate that the given value matches a certain regular expression.
• Error message keys: required, invalid

Takes one required argument:

• regex

  A regular expression specified either as a string or a compiled regular expression object.

Also takes max_length, min_length, strip, and empty_value which work just as they do for CharField.

• strip

  Defaults to False. If enabled, stripping will be applied before the regex validation.

SlugField

class SlugField(**kwargs)

• Default widget: TextInput
• Empty value: Whatever you’ve given as empty_value.
• Normalizes to: A string.
• Uses validate_slug or validate_unicode_slug to validate that the given value contains only letters, numbers, underscores, and hyphens.
• Error messages: required, invalid

This field is intended for use in representing a model SlugField in forms.

Takes two optional parameters:

• allow_unicode

  A boolean instructing the field to accept Unicode letters in addition to ASCII letters. Defaults to False.

• empty_value

  The value to use to represent “empty”. Defaults to an empty string.

TimeField

class TimeField(**kwargs)

• Default widget: TimeInput
• Empty value: None
• Normalizes to: A Python datetime.time object.
• Validates that the given value is either a datetime.time or string formatted in a particular time format.
• Error message keys: required, invalid

Takes one optional argument:

• input_formats

  An iterable of formats used to attempt to convert a string to a valid datetime.time object.

If no input_formats argument is provided, the default input formats are taken from TIME_INPUT_FORMATS if USE_L10N is False, or from the active locale format TIME_INPUT_FORMATS key if localization is enabled. See also format localization.

TypedChoiceField

class TypedChoiceField(**kwargs)

Just like a ChoiceField, except TypedChoiceField takes two extra arguments, coerce and empty_value.

• Default widget: Select
• Empty value: Whatever you’ve given as empty_value.
• Normalizes to: A value of the type provided by the coerce argument.
• Validates that the given value exists in the list of choices and can be coerced.
• Error message keys: required, invalid_choice

Takes extra arguments:

• coerce

  A function that takes one argument and returns a coerced value. Examples include the built-in int, float, bool and other types. Defaults to an identity function. Note that coercion happens after input validation, so it is possible to coerce to a value not present in choices.

• empty_value

  The value to use to represent “empty.” Defaults to the empty string; None is another common choice here. Note that this value will not be coerced by the function given in the coerce argument, so choose it accordingly.

TypedMultipleChoiceField

class TypedMultipleChoiceField(**kwargs)

Just like a MultipleChoiceField, except TypedMultipleChoiceField takes two extra arguments, coerce and empty_value.

• Default widget: SelectMultiple
• Empty value: Whatever you’ve given as empty_value
• Normalizes to: A list of values of the type provided by the coerce argument.
• Validates that the given values exists in the list of choices and can be coerced.
• Error message keys: required, invalid_choice

The invalid_choice error message may contain %(value)s, which will be replaced with the selected choice.

Takes two extra arguments, coerce and empty_value, as for TypedChoiceField.

URLField

class URLField(**kwargs)

• Default widget: URLInput
• Empty value: Whatever you’ve given as empty_value.
• Normalizes to: A string.
• Uses URLValidator to validate that the given value is a valid URL.
• Error message keys: required, invalid

Has the optional arguments max_length, min_length, and empty_value which work just as they do for CharField.

UUIDField

class UUIDField(**kwargs)

• Default widget: TextInput
• Empty value: None
• Normalizes to: A UUID object.
• Error message keys: required, invalid

This field will accept any string format accepted as the hex argument to the UUID constructor.

Slightly complex built-in Field classes

ComboField

class ComboField(**kwargs)

• Default widget: TextInput
• Empty value: '' (an empty string)
• Normalizes to: A string.
• Validates the given value against each of the fields specified as an argument to the ComboField.
• Error message keys: required, invalid

Takes one extra required argument:

• fields

  The list of fields that should be used to validate the field’s value (in the order in which they are provided).

  >>> from django.forms import ComboField
  >>> f = ComboField(fields=[CharField(max_length=20), EmailField()])
  >>> f.clean('test@example.com')
  'test@example.com'
  >>> f.clean('longemailaddress@example.com')
  Traceback (most recent call last):
  ...
  ValidationError: ['Ensure this value has at most 20 characters (it has 28).']

MultiValueField

class MultiValueField(fields=(), **kwargs)

• Default widget: TextInput
• Empty value: '' (an empty string)
• Normalizes to: the type returned by the compress method of the subclass.
• Validates the given value against each of the fields specified as an argument to the MultiValueField.
• Error message keys: required, invalid, incomplete

Aggregates the logic of multiple fields that together produce a single value.

This field is abstract and must be subclassed. In contrast with the single-value fields, subclasses of MultiValueField must not implement clean() but instead - implement compress().

Takes one extra required argument:

• fields

  A tuple of fields whose values are cleaned and subsequently combined into a single value. Each value of the field is cleaned by the corresponding field in fields – the first value is cleaned by the first field, the second value is cleaned by the second field, etc. Once all fields are cleaned, the list of clean values is combined into a single value by compress().

Also takes some optional arguments:

• require_all_fields

  Defaults to True, in which case a required validation error will be raised if no value is supplied for any field.

  When set to False, the Field.required attribute can be set to False for individual fields to make them optional. If no value is supplied for a required field, an incomplete validation error will be raised.

  A default incomplete error message can be defined on the MultiValueField subclass, or different messages can be defined on each individual field. For example:

  ``` from django.core.validators import RegexValidator

class PhoneField(MultiValueField):
    def __init__(self, **kwargs):
        # Define one message for all fields.
        error_messages = {
            "incomplete": "Enter a country calling code and a phone number.",
        }
        # Or define a different message for each field.
        fields = (
            CharField(
                error_messages={"incomplete": "Enter a country calling code."},
                validators=[
                    RegexValidator(r"^[0-9]+$", "Enter a valid country calling code."),
                ],
            ),
            CharField(
                error_messages={"incomplete": "Enter a phone number."},
                validators=[RegexValidator(r"^[0-9]+$", "Enter a valid phone number.")],
            ),
            CharField(
                validators=[RegexValidator(r"^[0-9]+$", "Enter a valid extension.")],
                required=False,
            ),
        )
        super().__init__(
            error_messages=error_messages,
            fields=fields,
            require_all_fields=False,
            **kwargs
        )
```

• widget

  Must be a subclass of django.forms.MultiWidget. Default value is TextInput, which probably is not very useful in this case.

• compress(data_list)

  Takes a list of valid values and returns a “compressed” version of those values – in a single value. For example, SplitDateTimeField is a subclass which combines a time field and a date field into a datetime object.

  This method must be implemented in the subclasses.

SplitDateTimeField

class SplitDateTimeField(**kwargs)

• Default widget: SplitDateTimeWidget
• Empty value: None
• Normalizes to: A Python datetime.datetime object.
• Validates that the given value is a datetime.datetime or string formatted in a particular datetime format.
• Error message keys: required, invalid, invalid_date, invalid_time

Takes two optional arguments:

• input_date_formats

  A list of formats used to attempt to convert a string to a valid datetime.date object.

If no input_date_formats argument is provided, the default input formats for DateField are used.

• input_time_formats

  A list of formats used to attempt to convert a string to a valid datetime.time object.

If no input_time_formats argument is provided, the default input formats for TimeField are used.

Fields which handle relationships

Two fields are available for representing relationships between models: ModelChoiceField and ModelMultipleChoiceField. Both of these fields require a single queryset parameter that is used to create the choices for the field. Upon form validation, these fields will place either one model object (in the case of ModelChoiceField) or multiple model objects (in the case of ModelMultipleChoiceField) into the cleaned_data dictionary of the form.

For more complex uses, you can specify queryset=None when declaring the form field and then populate the queryset in the form’s __init__() method:

class FooMultipleChoiceForm(forms.Form):
    foo_select = forms.ModelMultipleChoiceField(queryset=None)
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields["foo_select"].queryset = ...

Both ModelChoiceField and ModelMultipleChoiceField have an iterator attribute which specifies the class used to iterate over the queryset when generating choices. See Iterating relationship choices for details.

ModelChoiceField

class ModelChoiceField(**kwargs)

• Default widget: Select
• Empty value: None
• Normalizes to: A model instance.
• Validates that the given id exists in the queryset.
• Error message keys: required, invalid_choice

The invalid_choice error message may contain %(value)s, which will be replaced with the selected choice.

Allows the selection of a single model object, suitable for representing a foreign key. Note that the default widget for ModelChoiceField becomes impractical when the number of entries increases. You should avoid using it for more than 100 items.

A single argument is required:

• queryset

  A QuerySet of model objects from which the choices for the field are derived and which is used to validate the user’s selection. It’s evaluated when the form is rendered.

ModelChoiceField also takes several optional arguments:

• empty_label

  By default the <select> widget used by ModelChoiceField will have an empty choice at the top of the list. You can change the text of this label (which is "---------" by default) with the empty_label attribute, or you can disable the empty label entirely by setting empty_label to None:

  # A custom empty label
  field1 = forms.ModelChoiceField(queryset=..., empty_label="(Nothing)")
  # No empty label
  field2 = forms.ModelChoiceField(queryset=..., empty_label=None)

  Note that no empty choice is created (regardless of the value of empty_label) if a ModelChoiceField is required and has a default initial value, or a widget is set to RadioSelect and the blank argument is False.

• to_field_name

  This optional argument is used to specify the field to use as the value of the choices in the field’s widget. Be sure it’s a unique field for the model, otherwise the selected value could match more than one object. By default it is set to None, in which case the primary key of each object will be used. For example:

  # No custom to_field_name
  field1 = forms.ModelChoiceField(queryset=...)

  would yield:

  <select id="id_field1" name="field1">
  <option value="obj1.pk">Object1</option>
  <option value="obj2.pk">Object2</option>
  ...
  </select>

  and:

  # to_field_name provided
  field2 = forms.ModelChoiceField(queryset=..., to_field_name="name")

  would yield:

  <select id="id_field2" name="field2">
  <option value="obj1.name">Object1</option>
  <option value="obj2.name">Object2</option>
  ...
  </select>

• blank

  When using the RadioSelect widget, this optional boolean argument determines whether an empty choice is created. By default, blank is False, in which case no empty choice is created.

ModelChoiceField also has the attribute:

• iterator

  The iterator class used to generate field choices from queryset. By default, ModelChoiceIterator.

The __str__() method of the model will be called to generate string representations of the objects for use in the field’s choices. To provide customized representations, subclass ModelChoiceField and override label_from_instance. This method will receive a model object and should return a string suitable for representing it. For example:

from django.forms import ModelChoiceField
class MyModelChoiceField(ModelChoiceField):
    def label_from_instance(self, obj):
        return "My Object #%i" % obj.id

ModelMultipleChoiceField

class ModelMultipleChoiceField(**kwargs)

• Default widget: SelectMultiple
• Empty value: An empty QuerySet (self.queryset.none())
• Normalizes to: A QuerySet of model instances.
• Validates that every id in the given list of values exists in the queryset.
• Error message keys: required, invalid_list, invalid_choice, invalid_pk_value

The invalid_choice message may contain %(value)s and the invalid_pk_value message may contain %(pk)s, which will be substituted by the appropriate values.

Allows the selection of one or more model objects, suitable for representing a many-to-many relation. As with ModelChoiceField, you can use label_from_instance to customize the object representations.

A single argument is required:

• queryset

  Same as ModelChoiceField.queryset.

Takes one optional argument:

• to_field_name

  Same as ModelChoiceField.to_field_name.

ModelMultipleChoiceField also has the attribute:

• iterator

  Same as ModelChoiceField.iterator.

Iterating relationship choices

By default, ModelChoiceField and ModelMultipleChoiceField use ModelChoiceIterator to generate their field choices.

When iterated, ModelChoiceIterator yields 2-tuple choices containing ModelChoiceIteratorValue instances as the first value element in each choice. ModelChoiceIteratorValue wraps the choice value while maintaining a reference to the source model instance that can be used in custom widget implementations, for example, to add data-* attributes to <option> elements.

For example, consider the following models:

from django.db import models
class Topping(models.Model):
    name = models.CharField(max_length=100)
    price = models.DecimalField(decimal_places=2, max_digits=6)
    def __str__(self):
        return self.name
class Pizza(models.Model):
    topping = models.ForeignKey(Topping, on_delete=models.CASCADE)

You can use a Select widget subclass to include the value of Topping.price as the HTML attribute data-price for each <option> element:

from django import forms
class ToppingSelect(forms.Select):
    def create_option(
        self, name, value, label, selected, index, subindex=None, attrs=None
    ):
        option = super().create_option(
            name, value, label, selected, index, subindex, attrs
        )
        if value:
            option["attrs"]["data-price"] = value.instance.price
        return option
class PizzaForm(forms.ModelForm):
    class Meta:
        model = Pizza
        fields = ["topping"]
        widgets = {"topping": ToppingSelect}

This will render the Pizza.topping select as:

<select id="id_topping" name="topping" required>
<option value="" selected>---------</option>
<option value="1" data-price="1.50">mushrooms</option>
<option value="2" data-price="1.25">onions</option>
<option value="3" data-price="1.75">peppers</option>
<option value="4" data-price="2.00">pineapple</option>
</select>

For more advanced usage you may subclass ModelChoiceIterator in order to customize the yielded 2-tuple choices.

ModelChoiceIterator

class ModelChoiceIterator(field)

The default class assigned to the iterator attribute of ModelChoiceField and ModelMultipleChoiceField. An iterable that yields 2-tuple choices from the queryset.

A single argument is required:

• field

  The instance of ModelChoiceField or ModelMultipleChoiceField to iterate and yield choices.

ModelChoiceIterator has the following method:

• __iter__()

  Yields 2-tuple choices, in the (value, label) format used by ChoiceField.choices. The first value element is a ModelChoiceIteratorValue instance.

ModelChoiceIteratorValue

class ModelChoiceIteratorValue(value, instance)

Two arguments are required:

• value

  The value of the choice. This value is used to render the value attribute of an HTML <option> element.

• instance

  The model instance from the queryset. The instance can be accessed in custom ChoiceWidget.create_option() implementations to adjust the rendered HTML.

ModelChoiceIteratorValue has the following method:

• __str__()

  Return value as a string to be rendered in HTML.

Creating custom fields

If the built-in Field classes don’t meet your needs, you can create custom Field classes. To do this, create a subclass of django.forms.Field. Its only requirements are that it implement a clean() method and that its __init__() method accept the core arguments mentioned above (required, label, initial, widget, help_text).

You can also customize how a field will be accessed by overriding get_bound_field().