When you create a Form class, the most important part is defining the\nfields of the form. Each field has custom validation logic, along with a few\nother hooks.
Although the primary way you’ll use Field classes is in Form classes,\nyou can also instantiate them and use them directly to get a better idea of\nhow they work. Each Field instance has a clean() method, which takes\na single argument and either raises a django.forms.ValidationError\nexception or returns the clean value:
>>> from django import forms\n>>> f = forms.EmailField()\n>>> f.clean('foo@example.com')\n'foo@example.com'\n>>> f.clean('invalid email address')\nTraceback (most recent call last):\n...\nValidationError: ['Enter a valid email address.']\nEach Field class constructor takes at least these arguments. Some\nField classes take additional, field-specific arguments, but the following\nshould always be accepted:
requiredLink to this heading#By default, each Field class assumes the value is required, so if you pass\nan empty value – either None or the empty string ("") – then\nclean() will raise a ValidationError exception:
>>> from django import forms\n>>> f = forms.CharField()\n>>> f.clean('foo')\n'foo'\n>>> f.clean('')\nTraceback (most recent call last):\n...\nValidationError: ['This field is required.']\n>>> f.clean(None)\nTraceback (most recent call last):\n...\nValidationError: ['This field is required.']\n>>> f.clean(' ')\n' '\n>>> f.clean(0)\n'0'\n>>> f.clean(True)\n'True'\n>>> f.clean(False)\n'False'\nTo specify that a field is not required, pass required=False to the\nField constructor:
>>> f = forms.CharField(required=False)\n>>> f.clean('foo')\n'foo'\n>>> f.clean('')\n''\n>>> f.clean(None)\n''\n>>> f.clean(0)\n'0'\n>>> f.clean(True)\n'True'\n>>> f.clean(False)\n'False'\nIf a Field has required=False and you pass clean() an empty value,\nthen clean() will return a normalized empty value rather than raising\nValidationError. For CharField, this will be an empty string. For other\nField classes, it might be None. (This varies from field to field.)
Widgets of required form fields have the required HTML attribute. Set the\nForm.use_required_attribute attribute to False to disable it. The\nrequired attribute isn’t included on forms of formsets because the browser\nvalidation may not be correct when adding and deleting formsets.
labelLink to this heading#The label argument lets you specify the “human-friendly” label for this\nfield. This is used when the Field is displayed in a Form.
As explained in “Outputting forms as HTML” above, the default label for a\nField is generated from the field name by converting all underscores to\nspaces and upper-casing the first letter. Specify label if that default\nbehavior doesn’t result in an adequate label.
Here’s a full example Form that implements label for two of its fields.\nWe’ve specified auto_id=False to simplify the output:
>>> from django import forms\n>>> class CommentForm(forms.Form):\n... name = forms.CharField(label='Your name')\n... url = forms.URLField(label='Your website', required=False)\n... comment = forms.CharField()\n>>> f = CommentForm(auto_id=False)\n>>> print(f)\n<tr><th>Your name:</th><td><input type="text" name="name" required></td></tr>\n<tr><th>Your website:</th><td><input type="url" name="url"></td></tr>\n<tr><th>Comment:</th><td><input type="text" name="comment" required></td></tr>\nlabel_suffixLink to this heading#The label_suffix argument lets you override the form’s\nlabel_suffix on a per-field basis:
>>> class ContactForm(forms.Form):\n... age = forms.IntegerField()\n... nationality = forms.CharField()\n... captcha_answer = forms.IntegerField(label='2 + 2', label_suffix=' =')\n>>> f = ContactForm(label_suffix='?')\n>>> print(f.as_p())\n<p><label for="id_age">Age?</label> <input id="id_age" name="age" type="number" required></p>\n<p><label for="id_nationality">Nationality?</label> <input id="id_nationality" name="nationality" type="text" required></p>\n<p><label for="id_captcha_answer">2 + 2 =</label> <input id="id_captcha_answer" name="captcha_answer" type="number" required></p>\ninitialLink to this heading#The initial argument lets you specify the initial value to use when\nrendering 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\nfield is initialized to a particular value. For example:
\n>>> from django import forms\n>>> class CommentForm(forms.Form):\n... name = forms.CharField(initial='Your name')\n... url = forms.URLField(initial='http://')\n... comment = forms.CharField()\n>>> f = CommentForm(auto_id=False)\n>>> print(f)\n<tr><th>Name:</th><td><input type="text" name="name" value="Your name" required></td></tr>\n<tr><th>Url:</th><td><input type="url" name="url" value="http://" required></td></tr>\n<tr><th>Comment:</th><td><input type="text" name="comment" required></td></tr>\nYou may be thinking, why not just pass a dictionary of the initial values as\ndata when displaying the form? Well, if you do that, you’ll trigger validation,\nand the HTML output will include any validation errors:
\n>>> class CommentForm(forms.Form):\n... name = forms.CharField()\n... url = forms.URLField()\n... comment = forms.CharField()\n>>> default_data = {'name': 'Your name', 'url': 'http://'}\n>>> f = CommentForm(default_data, auto_id=False)\n>>> print(f)\n<tr><th>Name:</th><td><input type="text" name="name" value="Your name" required></td></tr>\n<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>\n<tr><th>Comment:</th><td><ul class="errorlist"><li>This field is required.</li></ul><input type="text" name="comment" required></td></tr>\nThis is why initial values are only displayed for unbound forms. For bound\nforms, the HTML output will use the bound data.
Also note that initial values are not used as “fallback” data in\nvalidation if a particular field’s value is not given. initial values are\nonly intended for initial form display:
>>> class CommentForm(forms.Form):\n... name = forms.CharField(initial='Your name')\n... url = forms.URLField(initial='http://')\n... comment = forms.CharField()\n>>> data = {'name': '', 'url': '', 'comment': 'Foo'}\n>>> f = CommentForm(data)\n>>> f.is_valid()\nFalse\n# The form does *not* fall back to using the initial values.\n>>> f.errors\n{'url': ['This field is required.'], 'name': ['This field is required.']}\nInstead of a constant, you can also pass any callable:
\n>>> import datetime\n>>> class DateForm(forms.Form):\n... day = forms.DateField(initial=datetime.date.today)\n>>> print(DateForm())\n<tr><th>Day:</th><td><input type="text" name="day" value="12/23/2008" required><td></tr>\nThe callable will be evaluated only when the unbound form is displayed, not when it is defined.
\nwidgetLink to this heading#The widget argument lets you specify a Widget class to use when\nrendering this Field. See Widgets for more information.
help_textLink to this heading#The help_text argument lets you specify descriptive text for this\nField. If you provide help_text, it will be displayed next to the\nField when the Field is rendered by one of the convenience Form\nmethods (e.g., as_ul()).
Like the model field’s help_text, this value\nisn’t HTML-escaped in automatically-generated forms.
Here’s a full example Form that implements help_text for two of its\nfields. We’ve specified auto_id=False to simplify the output:
>>> from django import forms\n>>> class HelpTextContactForm(forms.Form):\n... subject = forms.CharField(max_length=100, help_text='100 characters max.')\n... message = forms.CharField()\n... sender = forms.EmailField(help_text='A valid email address, please.')\n... cc_myself = forms.BooleanField(required=False)\n>>> f = HelpTextContactForm(auto_id=False)\n>>> print(f.as_table())\n<tr><th>Subject:</th><td><input type="text" name="subject" maxlength="100" required><br><span class="helptext">100 characters max.</span></td></tr>\n<tr><th>Message:</th><td><input type="text" name="message" required></td></tr>\n<tr><th>Sender:</th><td><input type="email" name="sender" required><br>A valid email address, please.</td></tr>\n<tr><th>Cc myself:</th><td><input type="checkbox" name="cc_myself"></td></tr>\n>>> print(f.as_ul()))\n<li>Subject: <input type="text" name="subject" maxlength="100" required> <span class="helptext">100 characters max.</span></li>\n<li>Message: <input type="text" name="message" required></li>\n<li>Sender: <input type="email" name="sender" required> A valid email address, please.</li>\n<li>Cc myself: <input type="checkbox" name="cc_myself"></li>\n>>> print(f.as_p())\n<p>Subject: <input type="text" name="subject" maxlength="100" required> <span class="helptext">100 characters max.</span></p>\n<p>Message: <input type="text" name="message" required></p>\n<p>Sender: <input type="email" name="sender" required> A valid email address, please.</p>\n<p>Cc myself: <input type="checkbox" name="cc_myself"></p>\nerror_messagesLink to this heading#The error_messages argument lets you override the default messages that the\nfield will raise. Pass in a dictionary with keys matching the error messages you\nwant to override. For example, here is the default error message:
>>> from django import forms\n>>> generic = forms.CharField()\n>>> generic.clean('')\nTraceback (most recent call last):\n ...\nValidationError: ['This field is required.']\nAnd here is a custom error message:
\n>>> name = forms.CharField(error_messages={'required': 'Please enter your name'})\n>>> name.clean('')\nTraceback (most recent call last):\n ...\nValidationError: ['Please enter your name']\nIn the built-in Field classes section below, each Field defines the\nerror message keys it uses.
validatorsLink to this heading#The validators argument lets you provide a list of validation functions\nfor this field.
See the validators documentation for more information.
\nlocalizeLink to this heading#The localize argument enables the localization of form data input, as well\nas the rendered output.
See the format localization documentation for\nmore information.
\ndisabledLink to this heading#The disabled boolean argument, when set to True, disables a form field\nusing the disabled HTML attribute so that it won’t be editable by users.\nEven if a user tampers with the field’s value submitted to the server, it will\nbe ignored in favor of the value from the form’s initial data.
has_changed()Link to this heading#The has_changed() method is used to determine if the field value has changed\nfrom the initial value. Returns True or False.
See the Form.has_changed() documentation for more information.
Field classesLink to this heading#Naturally, the forms library comes with a set of Field classes that\nrepresent common validation needs. This section documents each built-in field.
For each field, we describe the default widget used if you don’t specify\nwidget. We also specify the value returned when you provide an empty value\n(see the section on required above to understand what that means).
BooleanFieldLink to this heading#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\nthe field has required=True.
Error message keys: required
CharFieldLink to this heading#Default widget: TextInput
Empty value: Whatever you’ve given as empty_value.
Normalizes to: A string.
Uses MaxLengthValidator and\nMinLengthValidator if max_length and\nmin_length are provided. Otherwise, all inputs are valid.
Error message keys: required, max_length, min_length
Has three optional arguments for validation:
\nIf provided, these arguments ensure that the string is at most or at least\nthe given length.
\nIf True (default), the value will be stripped of leading and\ntrailing whitespace.
The value to use to represent “empty”. Defaults to an empty string.
\nChoiceFieldLink to this heading#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\nreplaced with the selected choice.
Takes one extra argument:
\nEither an iterable (e.g., a list or tuple) of 2-tuples to use as\nchoices for this field, or a callable that returns such an iterable.\nThis argument accepts the same formats as the choices argument to a\nmodel field. See the model field reference documentation on\nchoices for more details. If the argument is a\ncallable, it is evaluated each time the field’s form is initialized.\nDefaults to an empty list.
TypedChoiceFieldLink to this heading#Just like a ChoiceField, except TypedChoiceField takes two\nextra 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\nargument.
Validates that the given value exists in the list of choices and can be\ncoerced.
Error message keys: required, invalid_choice
Takes extra arguments:
\nA function that takes one argument and returns a coerced value. Examples\ninclude the built-in int, float, bool and other types. Defaults\nto an identity function. Note that coercion happens after input\nvalidation, so it is possible to coerce to a value not present in\nchoices.
The value to use to represent “empty.” Defaults to the empty string;\nNone is another common choice here. Note that this value will not be\ncoerced by the function given in the coerce argument, so choose it\naccordingly.
DateFieldLink to this heading#Default widget: DateInput
Empty value: None
Normalizes to: A Python datetime.date object.
Validates that the given value is either a datetime.date,\ndatetime.datetime or string formatted in a particular date format.
Error message keys: required, invalid
Takes one optional argument:
\nA list of formats used to attempt to convert a string to a valid\ndatetime.date object.
If no input_formats argument is provided, the default input formats are:
['%Y-%m-%d', # '2006-10-25'\n '%m/%d/%Y', # '10/25/2006'\n '%m/%d/%y'] # '10/25/06'\nAdditionally, if you specify USE_L10N=False in your settings, the\nfollowing will also be included in the default input formats:
['%b %d %Y', # 'Oct 25 2006'\n '%b %d, %Y', # 'Oct 25, 2006'\n '%d %b %Y', # '25 Oct 2006'\n '%d %b, %Y', # '25 Oct, 2006'\n '%B %d %Y', # 'October 25 2006'\n '%B %d, %Y', # 'October 25, 2006'\n '%d %B %Y', # '25 October 2006'\n '%d %B, %Y'] # '25 October, 2006'\nSee also format localization.
\nDateTimeFieldLink to this heading#Default widget: DateTimeInput
Empty value: None
Normalizes to: A Python datetime.datetime object.
Validates that the given value is either a datetime.datetime,\ndatetime.date or string formatted in a particular datetime format.
Error message keys: required, invalid
Takes one optional argument:
\nA list of formats used to attempt to convert a string to a valid\ndatetime.datetime object.
If no input_formats argument is provided, the default input formats are:
['%Y-%m-%d %H:%M:%S', # '2006-10-25 14:30:59'\n '%Y-%m-%d %H:%M', # '2006-10-25 14:30'\n '%Y-%m-%d', # '2006-10-25'\n '%m/%d/%Y %H:%M:%S', # '10/25/2006 14:30:59'\n '%m/%d/%Y %H:%M', # '10/25/2006 14:30'\n '%m/%d/%Y', # '10/25/2006'\n '%m/%d/%y %H:%M:%S', # '10/25/06 14:30:59'\n '%m/%d/%y %H:%M', # '10/25/06 14:30'\n '%m/%d/%y'] # '10/25/06'\nSee also format localization.
\nDecimalFieldLink to this heading#Default widget: NumberInput when Field.localize is\nFalse, else TextInput.
Empty value: None
Normalizes to: A Python decimal.
Validates that the given value is a decimal. Uses\nMaxValueValidator and\nMinValueValidator if max_value and\nmin_value are provided. Leading and trailing whitespace is ignored.
Error message keys: required, invalid, max_value,\nmin_value, max_digits, max_decimal_places,\nmax_whole_digits
The max_value and min_value error messages may contain\n%(limit_value)s, which will be substituted by the appropriate limit.\nSimilarly, the max_digits, max_decimal_places and\nmax_whole_digits error messages may contain %(max)s.
Takes four optional arguments:
\nThese control the range of values permitted in the field, and should be\ngiven as decimal.Decimal values.
The maximum number of digits (those before the decimal point plus those\nafter the decimal point, with leading zeros stripped) permitted in the\nvalue.
\nThe maximum number of decimal places permitted.
\nDurationFieldLink to this heading#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\ntimedelta. The value must be between datetime.timedelta.min\nand datetime.timedelta.max.
Error message keys: required, invalid, overflow.
Accepts any format understood by\nparse_duration().
EmailFieldLink to this heading#Default widget: EmailInput
Empty value: '' (an empty string)
Normalizes to: A string.
Uses EmailValidator to validate that\nthe given value is a valid email address, using a moderately complex\nregular expression.
Error message keys: required, invalid
Has two optional arguments for validation, max_length and min_length.\nIf provided, these arguments ensure that the string is at most or at least the\ngiven length.
FileFieldLink to this heading#Default widget: ClearableFileInput
Empty value: None
Normalizes to: An UploadedFile object that wraps the file content\nand 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,\nmax_length
Has two optional arguments for validation, max_length and\nallow_empty_file. If provided, these ensure that the file name is at\nmost the given length, and that validation will succeed even if the file\ncontent is empty.
To learn more about the UploadedFile object, see the file uploads\ndocumentation.
When you use a FileField in a form, you must also remember to\nbind the file data to the form.
The max_length error refers to the length of the filename. In the error\nmessage for that key, %(max)d will be replaced with the maximum filename\nlength and %(length)d will be replaced with the current filename length.
FilePathFieldLink to this heading#Default widget: Select
Empty value: None
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\nextra arguments; only path is required:
The absolute path to the directory whose contents you want listed. This\ndirectory must exist.
\nIf False (the default) only the direct contents of path will be\noffered as choices. If True, the directory will be descended into\nrecursively and all descendants will be listed as choices.
A regular expression pattern; only files with names matching this expression\nwill be allowed as choices.
\nOptional. Either True or False. Default is True. Specifies\nwhether files in the specified location should be included. Either this or\nallow_folders must be True.
Optional. Either True or False. Default is False. Specifies\nwhether folders in the specified location should be included. Either this or\nallow_files must be True.
FloatFieldLink to this heading#Default widget: NumberInput when Field.localize is\nFalse, else TextInput.
Empty value: None
Normalizes to: A Python float.
Validates that the given value is a float. Uses\nMaxValueValidator and\nMinValueValidator if max_value and\nmin_value are provided. Leading and trailing whitespace is allowed,\nas in Python’s float() function.
Error message keys: required, invalid, max_value,\nmin_value
Takes two optional arguments for validation, max_value and min_value.\nThese control the range of values permitted in the field.
ImageFieldLink to this heading#Default widget: ClearableFileInput
Empty value: None
Normalizes to: An UploadedFile object that wraps the file content\nand file name into a single object.
Validates that file data has been bound to the form. Also uses\nFileExtensionValidator to validate that\nthe file extension is supported by Pillow.
Error message keys: required, invalid, missing, empty,\ninvalid_image
Using an ImageField requires that Pillow is installed with support\nfor the image formats you use. If you encounter a corrupt image error\nwhen you upload an image, it usually means that Pillow doesn’t understand\nits format. To fix this, install the appropriate library and reinstall\nPillow.
When you use an ImageField on a form, you must also remember to\nbind the file data to the form.
After the field has been cleaned and validated, the UploadedFile\nobject will have an additional image attribute containing the Pillow\nImage instance used to check if the file was a valid image. Also,\nUploadedFile.content_type will be updated with the image’s content type\nif Pillow can determine it, otherwise it will be set to None.
IntegerFieldLink to this heading#Default widget: NumberInput when Field.localize is\nFalse, else TextInput.
Empty value: None
Normalizes to: A Python integer.
Validates that the given value is an integer. Uses\nMaxValueValidator and\nMinValueValidator if max_value and\nmin_value are provided. Leading and trailing whitespace is allowed,\nas in Python’s int() function.
Error message keys: required, invalid, max_value,\nmin_value
The max_value and min_value error messages may contain\n%(limit_value)s, which will be substituted by the appropriate limit.
Takes two optional arguments for validation:
\nThese control the range of values permitted in the field.
\nGenericIPAddressFieldLink to this heading#A field containing either an IPv4 or an IPv6 address.
\nDefault 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,\nincluding using the IPv4 format suggested in paragraph 3 of that section, like\n::ffff:192.0.2.0. For example, 2001:0::0:01 would be normalized to\n2001::1, and ::ffff:0a0a:0a0a to ::ffff:10.10.10.10. All characters\nare converted to lowercase.
Takes two optional arguments:
\nLimits valid inputs to the specified protocol.\nAccepted values are both (default), IPv4\nor IPv6. Matching is case insensitive.
Unpacks IPv4 mapped addresses like ::ffff:192.0.2.1.\nIf this option is enabled that address would be unpacked to\n192.0.2.1. Default is disabled. Can only be used\nwhen protocol is set to 'both'.
MultipleChoiceFieldLink to this heading#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\nof choices.
Error message keys: required, invalid_choice, invalid_list
The invalid_choice error message may contain %(value)s, which will be\nreplaced with the selected choice.
Takes one extra required argument, choices, as for ChoiceField.
TypedMultipleChoiceFieldLink to this heading#Just like a MultipleChoiceField, except TypedMultipleChoiceField\ntakes 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\nargument.
Validates that the given values exists in the list of choices and can be\ncoerced.
Error message keys: required, invalid_choice
The invalid_choice error message may contain %(value)s, which will be\nreplaced with the selected choice.
Takes two extra arguments, coerce and empty_value, as for\nTypedChoiceField.
NullBooleanFieldLink to this heading#Default widget: NullBooleanSelect
Empty value: None
Normalizes to: A Python True, False or None value.
Validates nothing (i.e., it never raises a ValidationError).
RegexFieldLink to this heading#Default widget: TextInput
Empty value: '' (an empty string)
Normalizes to: A string.
Uses RegexValidator to validate that\nthe given value matches a certain regular expression.
Error message keys: required, invalid
Takes one required argument:
\nA regular expression specified either as a string or a compiled regular\nexpression object.
\nAlso takes max_length, min_length, and strip, which work just\nas they do for CharField.
Defaults to False. If enabled, stripping will be applied before the\nregex validation.
SlugFieldLink to this heading#Default widget: TextInput
Empty value: '' (an empty string)
Normalizes to: A string.
Uses validate_slug or\nvalidate_unicode_slug to validate that\nthe given value contains only letters, numbers, underscores, and hyphens.
Error messages: required, invalid
This field is intended for use in representing a model\nSlugField in forms.
Takes an optional parameter:
\nA boolean instructing the field to accept Unicode letters in addition\nto ASCII letters. Defaults to False.
TimeFieldLink to this heading#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\nformatted in a particular time format.
Error message keys: required, invalid
Takes one optional argument:
\nA list of formats used to attempt to convert a string to a valid\ndatetime.time object.
If no input_formats argument is provided, the default input formats are:
'%H:%M:%S', # '14:30:59'\n'%H:%M', # '14:30'\nURLFieldLink to this heading#Default widget: URLInput
Empty value: '' (an empty string)
Normalizes to: A string.
Uses URLValidator to validate that the\ngiven value is a valid URL.
Error message keys: required, invalid
Takes the following optional arguments:
\nThese are the same as CharField.max_length and CharField.min_length.
UUIDFieldLink to this heading#Default widget: TextInput
Empty value: '' (an empty string)
Normalizes to: A UUID object.
Error message keys: required, invalid
This field will accept any string format accepted as the hex argument\nto the UUID constructor.
Field classesLink to this heading#ComboFieldLink to this heading#Default widget: TextInput
Empty value: '' (an empty string)
Normalizes to: A string.
Validates the given value against each of the fields specified\nas an argument to the ComboField.
Error message keys: required, invalid
Takes one extra required argument:
\nThe list of fields that should be used to validate the field’s value (in\nthe order in which they are provided).
\n>>> from django.forms import ComboField\n>>> f = ComboField(fields=[CharField(max_length=20), EmailField()])\n>>> f.clean('test@example.com')\n'test@example.com'\n>>> f.clean('longemailaddress@example.com')\nTraceback (most recent call last):\n...\nValidationError: ['Ensure this value has at most 20 characters (it has 28).']\nMultiValueFieldLink to this heading#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\nas an argument to the MultiValueField.
Error message keys: required, invalid, incomplete
Aggregates the logic of multiple fields that together produce a single\nvalue.
\nThis field is abstract and must be subclassed. In contrast with the\nsingle-value fields, subclasses of MultiValueField must not\nimplement clean() but instead - implement\ncompress().
Takes one extra required argument:
\nA tuple of fields whose values are cleaned and subsequently combined\ninto a single value. Each value of the field is cleaned by the\ncorresponding field in fields – the first value is cleaned by the\nfirst field, the second value is cleaned by the second field, etc.\nOnce all fields are cleaned, the list of clean values is combined into\na single value by compress().
Also takes some optional arguments:
\nDefaults to True, in which case a required validation error\nwill be raised if no value is supplied for any field.
When set to False, the Field.required attribute can be set\nto False for individual fields to make them optional. If no value\nis supplied for a required field, an incomplete validation error\nwill be raised.
A default incomplete error message can be defined on the\nMultiValueField subclass, or different messages can be defined\non each individual field. For example:
from django.core.validators import RegexValidator\n\nclass PhoneField(MultiValueField):\n def __init__(self, **kwargs):\n # Define one message for all fields.\n error_messages = {\n 'incomplete': 'Enter a country calling code and a phone number.',\n }\n # Or define a different message for each field.\n fields = (\n CharField(\n error_messages={'incomplete': 'Enter a country calling code.'},\n validators=[\n RegexValidator(r'^[0-9]+$', 'Enter a valid country calling code.'),\n ],\n ),\n CharField(\n error_messages={'incomplete': 'Enter a phone number.'},\n validators=[RegexValidator(r'^[0-9]+$', 'Enter a valid phone number.')],\n ),\n CharField(\n validators=[RegexValidator(r'^[0-9]+$', 'Enter a valid extension.')],\n required=False,\n ),\n )\n super().__init__(\n error_messages=error_messages, fields=fields,\n require_all_fields=False, **kwargs\n )\nMust be a subclass of django.forms.MultiWidget.\nDefault value is TextInput, which\nprobably is not very useful in this case.
Takes a list of valid values and returns a “compressed” version of\nthose values – in a single value. For example,\nSplitDateTimeField is a subclass which combines a time field\nand a date field into a datetime object.
This method must be implemented in the subclasses.
\nSplitDateTimeFieldLink to this heading#Default widget: SplitDateTimeWidget
Empty value: None
Normalizes to: A Python datetime.datetime object.
Validates that the given value is a datetime.datetime or string\nformatted in a particular datetime format.
Error message keys: required, invalid, invalid_date,\ninvalid_time
Takes two optional arguments:
\nA list of formats used to attempt to convert a string to a valid\ndatetime.date object.
If no input_date_formats argument is provided, the default input formats\nfor DateField are used.
A list of formats used to attempt to convert a string to a valid\ndatetime.time object.
If no input_time_formats argument is provided, the default input formats\nfor TimeField are used.
Two fields are available for representing relationships between\nmodels: ModelChoiceField and\nModelMultipleChoiceField. Both of these fields require a\nsingle queryset parameter that is used to create the choices for\nthe field. Upon form validation, these fields will place either one\nmodel object (in the case of ModelChoiceField) or multiple model\nobjects (in the case of ModelMultipleChoiceField) into the\ncleaned_data dictionary of the form.
For more complex uses, you can specify queryset=None when declaring the\nform field and then populate the queryset in the form’s __init__()\nmethod:
class FooMultipleChoiceForm(forms.Form):\n foo_select = forms.ModelMultipleChoiceField(queryset=None)\n\n def __init__(self, *args, **kwargs):\n super().__init__(*args, **kwargs)\n self.fields['foo_select'].queryset = ...\nModelChoiceFieldLink to this heading#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
Allows the selection of a single model object, suitable for representing a\nforeign key. Note that the default widget for ModelChoiceField becomes\nimpractical when the number of entries increases. You should avoid using it\nfor more than 100 items.
A single argument is required:
\nA QuerySet of model objects from which the choices for the field\nare derived and which is used to validate the user’s selection. It’s\nevaluated when the form is rendered.
ModelChoiceField also takes two optional arguments:
By default the <select> widget used by ModelChoiceField will have an\nempty choice at the top of the list. You can change the text of this\nlabel (which is "---------" by default) with the empty_label\nattribute, or you can disable the empty label entirely by setting\nempty_label to None:
# A custom empty label\nfield1 = forms.ModelChoiceField(queryset=..., empty_label="(Nothing)")\n\n# No empty label\nfield2 = forms.ModelChoiceField(queryset=..., empty_label=None)\nNote that if a ModelChoiceField is required and has a default\ninitial value, no empty choice is created (regardless of the value\nof empty_label).
This optional argument is used to specify the field to use as the value\nof the choices in the field’s widget. Be sure it’s a unique field for\nthe model, otherwise the selected value could match more than one\nobject. By default it is set to None, in which case the primary key\nof each object will be used. For example:
# No custom to_field_name\nfield1 = forms.ModelChoiceField(queryset=...)\nwould yield:
\n<select id="id_field1" name="field1">\n<option value="obj1.pk">Object1</option>\n<option value="obj2.pk">Object2</option>\n...\n</select>\nand:
\n# to_field_name provided\nfield2 = forms.ModelChoiceField(queryset=..., to_field_name="name")\nwould yield:
\n<select id="id_field2" name="field2">\n<option value="obj1.name">Object1</option>\n<option value="obj2.name">Object2</option>\n...\n</select>\nThe __str__() method of the model will be called to generate string\nrepresentations of the objects for use in the field’s choices. To provide\ncustomized representations, subclass ModelChoiceField and override\nlabel_from_instance. This method will receive a model object and should\nreturn a string suitable for representing it. For example:
from django.forms import ModelChoiceField\n\nclass MyModelChoiceField(ModelChoiceField):\n def label_from_instance(self, obj):\n return "My Object #%i" % obj.id\nModelMultipleChoiceFieldLink to this heading#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\nqueryset.
Error message keys: required, list, invalid_choice,\ninvalid_pk_value
The invalid_choice message may contain %(value)s and the\ninvalid_pk_value message may contain %(pk)s, which will be\nsubstituted by the appropriate values.
Allows the selection of one or more model objects, suitable for\nrepresenting a many-to-many relation. As with ModelChoiceField,\nyou can use label_from_instance to customize the object\nrepresentations.
A single argument is required:
\nSame as ModelChoiceField.queryset.
Takes one optional argument:
\nSame as ModelChoiceField.to_field_name.
If the built-in Field classes don’t meet your needs, you can easily create\ncustom Field classes. To do this, just create a subclass of\ndjango.forms.Field. Its only requirements are that it implement a\nclean() method and that its __init__() method accept the core arguments\nmentioned above (required, label, initial, widget,\nhelp_text).
You can also customize how a field will be accessed by overriding\nget_bound_field().