Form fields¶
When you create aForm class, the most important part is defining thefields of the form. Each field has custom validation logic, along with a fewother hooks.
Although the primary way you’ll useField classes is inForm classes,you can also instantiate them and use them directly to get a better idea ofhow they work. EachField instance has aclean() method, which takesa single argument and either raises adjango.forms.ValidationErrorexception or returns the clean value:
>>>fromdjangoimportforms>>>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¶
EachField class constructor takes at least these arguments. SomeField classes take additional, field-specific arguments, but the followingshouldalways be accepted:
required¶
Field.required¶
By default, eachField class assumes the value is required, so if you passan empty value – eitherNone or the empty string ("") – thenclean() will raise aValidationError exception:
>>>fromdjangoimportforms>>>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 isnot required, passrequired=False to theField 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 aField hasrequired=False and you passclean() an empty value,thenclean() will return anormalized empty value rather than raisingValidationError. ForCharField, this will be a Unicode empty string.For otherField classes, it might beNone. (This varies from field tofield.)
Widgets of required form fields have therequired HTML attribute. Set theForm.use_required_attribute attribute toFalse to disable it. Therequired attribute isn’t included on forms of formsets because the browservalidation may not be correct when adding and deleting formsets.
Support for therequired HTML attribute was added.
label¶
Field.label¶
Thelabel argument lets you specify the “human-friendly” label for thisfield. This is used when theField is displayed in aForm.
As explained in “Outputting forms as HTML” above, the default label for aField is generated from the field name by converting all underscores tospaces and upper-casing the first letter. Specifylabel if that defaultbehavior doesn’t result in an adequate label.
Here’s a full exampleForm that implementslabel for two of its fields.We’ve specifiedauto_id=False to simplify the output:
>>>fromdjangoimportforms>>>classCommentForm(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¶
Thelabel_suffix argument lets you override the form’slabel_suffix on a per-field basis:
>>>classContactForm(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¶
Theinitial argument lets you specify the initial value to use whenrendering thisField in an unboundForm.
To specify dynamic initial data, see theForm.initial parameter.
The use-case for this is when you want to display an “empty” form in which afield is initialized to a particular value. For example:
>>>fromdjangoimportforms>>>classCommentForm(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 asdata when displaying the form? Well, if you do that, you’ll trigger validation,and the HTML output will include any validation errors:
>>>classCommentForm(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 whyinitial values are only displayed for unbound forms. For boundforms, the HTML output will use the bound data.
Also note thatinitial values arenot used as “fallback” data invalidation if a particular field’s value is not given.initial values areonly intended for initial form display:
>>>classCommentForm(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:
>>>importdatetime>>>classDateForm(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¶
Thewidget argument lets you specify aWidget class to use whenrendering thisField. SeeWidgets for more information.
help_text¶
Field.help_text¶
Thehelp_text argument lets you specify descriptive text for thisField. If you providehelp_text, it will be displayed next to theField when theField is rendered by one of the convenienceFormmethods (e.g.,as_ul()).
Like the model field’shelp_text, this valueisn’t HTML-escaped in automatically-generated forms.
Here’s a full exampleForm that implementshelp_text for two of itsfields. We’ve specifiedauto_id=False to simplify the output:
>>>fromdjangoimportforms>>>classHelpTextContactForm(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¶
Theerror_messages argument lets you override the default messages that thefield will raise. Pass in a dictionary with keys matching the error messages youwant to override. For example, here is the default error message:
>>>fromdjangoimportforms>>>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 thebuilt-in Field classes section below, eachField defines theerror message keys it uses.
validators¶
Field.validators¶
Thevalidators argument lets you provide a list of validation functionsfor this field.
See thevalidators documentation for more information.
localize¶
Field.localize¶
Thelocalize argument enables the localization of form data input, as wellas the rendered output.
See theformat localization documentation formore information.
disabled¶
Field.disabled¶
Thedisabled boolean argument, when set toTrue, disables a form fieldusing thedisabled 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 willbe ignored in favor of the value from the form’s initial data.
Checking if the field data has changed¶
has_changed()¶
Thehas_changed() method is used to determine if the field value has changedfrom the initial value. ReturnsTrue orFalse.
See theForm.has_changed() documentation for more information.
Built-inField classes¶
Naturally, theforms library comes with a set ofField classes thatrepresent common validation needs. This section documents each built-in field.
For each field, we describe the default widget used if you don’t specifywidget. We also specify the value returned when you provide an empty value(see the section onrequired above to understand what that means).
BooleanField¶
- class
BooleanField(**kwargs)[source]¶ - Default widget:
CheckboxInput - Empty value:
False - Normalizes to: A Python
TrueorFalsevalue. - Validates that the value is
True(e.g. the check box is checked) ifthe field hasrequired=True. - Error message keys:
required
Note
Since all
Fieldsubclasses haverequired=Trueby default, thevalidation condition here is important. If you want to include a booleanin your form that can be eitherTrueorFalse(e.g. a checked orunchecked checkbox), you must remember to pass inrequired=Falsewhencreating theBooleanField.- Default widget:
CharField¶
- class
CharField(**kwargs)[source]¶ - Default widget:
TextInput - Empty value:
''(an empty string) - Normalizes to: A Unicode object.
- Validates
max_lengthormin_length, if they are provided.Otherwise, all inputs are valid. - Error message keys:
required,max_length,min_length
Has three optional arguments for validation:
max_length¶
min_length¶
If provided, these arguments ensure that the string is at most or at leastthe given length.
strip¶- New in Django 1.9.
If
True(default), the value will be stripped of leading andtrailing whitespace.
- Default widget:
ChoiceField¶
- class
ChoiceField(**kwargs)[source]¶ - Default widget:
Select - Empty value:
''(an empty string) - Normalizes to: A Unicode object.
- Validates that the given value exists in the list of choices.
- Error message keys:
required,invalid_choice
The
invalid_choiceerror message may contain%(value)s, which will bereplaced with the selected choice.Takes one extra required argument:
choices¶Either an iterable (e.g., a list or tuple) of 2-tuples to use aschoices for this field, or a callable that returns such an iterable.This argument accepts the same formats as the
choicesargument to amodel field. See themodel field reference documentation onchoices for more details. If the argument is acallable, it is evaluated each time the field’s form is initialized.
- Default widget:
TypedChoiceField¶
- class
TypedChoiceField(**kwargs)[source]¶ Just like a
ChoiceField, exceptTypedChoiceFieldtakes twoextra arguments,coerceandempty_value.- Default widget:
Select - Empty value: Whatever you’ve given as
empty_value. - Normalizes to: A value of the type provided by the
coerceargument. - Validates that the given value exists in the list of choices and can becoerced.
- Error message keys:
required,invalid_choice
Takes extra arguments:
coerce¶A function that takes one argument and returns a coerced value. Examplesinclude the built-in
int,float,booland other types. Defaultsto an identity function. Note that coercion happens after inputvalidation, so it is possible to coerce to a value not present inchoices.
empty_value¶The value to use to represent “empty.” Defaults to the empty string;
Noneis another common choice here. Note that this value will not becoerced by the function given in thecoerceargument, so choose itaccordingly.
- Default widget:
DateField¶
- class
DateField(**kwargs)[source]¶ - Default widget:
DateInput - Empty value:
None - Normalizes to: A Python
datetime.dateobject. - Validates that the given value is either a
datetime.date,datetime.datetimeor string formatted in a particular date format. - Error message keys:
required,invalid
Takes one optional argument:
input_formats¶A list of formats used to attempt to convert a string to a valid
datetime.dateobject.
If no
input_formatsargument is provided, the default input formats are:['%Y-%m-%d',# '2006-10-25''%m/%d/%Y',# '10/25/2006''%m/%d/%y']# '10/25/06'
Additionally, if you specify
USE_L10N=Falsein your settings, thefollowing will also be included in the default input formats:['%b%d %Y',# 'Oct 25 2006''%b%d, %Y',# 'Oct 25, 2006''%d %b %Y',# '25 Oct 2006''%d %b, %Y',# '25 Oct, 2006''%B%d %Y',# 'October 25 2006''%B%d, %Y',# 'October 25, 2006''%d %B %Y',# '25 October 2006''%d %B, %Y']# '25 October, 2006'
See alsoformat localization.
- Default widget:
DateTimeField¶
- class
DateTimeField(**kwargs)[source]¶ - Default widget:
DateTimeInput - Empty value:
None - Normalizes to: A Python
datetime.datetimeobject. - Validates that the given value is either a
datetime.datetime,datetime.dateor string formatted in a particular datetime format. - Error message keys:
required,invalid
Takes one optional argument:
input_formats¶A list of formats used to attempt to convert a string to a valid
datetime.datetimeobject.
If no
input_formatsargument is provided, the default input formats are:['%Y-%m-%d %H:%M:%S',# '2006-10-25 14:30:59''%Y-%m-%d %H:%M',# '2006-10-25 14:30''%Y-%m-%d',# '2006-10-25''%m/%d/%Y %H:%M:%S',# '10/25/2006 14:30:59''%m/%d/%Y %H:%M',# '10/25/2006 14:30''%m/%d/%Y',# '10/25/2006''%m/%d/%y %H:%M:%S',# '10/25/06 14:30:59''%m/%d/%y %H:%M',# '10/25/06 14:30''%m/%d/%y']# '10/25/06'
See alsoformat localization.
- Default widget:
DecimalField¶
- class
DecimalField(**kwargs)[source]¶ - Default widget:
NumberInputwhenField.localizeisFalse, elseTextInput. - Empty value:
None - Normalizes to: A Python
decimal. - Validates that the given value is a decimal. Leading and trailingwhitespace is ignored.
- Error message keys:
required,invalid,max_value,min_value,max_digits,max_decimal_places,max_whole_digits
The
max_valueandmin_valueerror messages may contain%(limit_value)s, which will be substituted by the appropriate limit.Similarly, themax_digits,max_decimal_placesandmax_whole_digitserror messages may contain%(max)s.Takes four optional arguments:
max_value¶
min_value¶These control the range of values permitted in the field, and should begiven as
decimal.Decimalvalues.
max_digits¶The maximum number of digits (those before the decimal point plus thoseafter the decimal point, with leading zeros stripped) permitted in thevalue.
decimal_places¶The maximum number of decimal places permitted.
- Default widget:
DurationField¶
- class
DurationField(**kwargs)[source]¶ - 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. - Error message keys:
required,invalid.
Accepts any format understood by
parse_duration().- Default widget:
EmailField¶
- class
EmailField(**kwargs)[source]¶ - Default widget:
EmailInput - Empty value:
''(an empty string) - Normalizes to: A Unicode object.
- Validates that the given value is a valid email address, using amoderately complex regular expression.
- Error message keys:
required,invalid
Has two optional arguments for validation,
max_lengthandmin_length.If provided, these arguments ensure that the string is at most or at least thegiven length.- Default widget:
FileField¶
- class
FileField(**kwargs)[source]¶ - Default widget:
ClearableFileInput - Empty value:
None - Normalizes to: An
UploadedFileobject that wraps the file contentand 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 two optional arguments for validation,
max_lengthandallow_empty_file. If provided, these ensure that the file name is atmost the given length, and that validation will succeed even if the filecontent is empty.To learn more about the
UploadedFileobject, see thefile uploadsdocumentation.When you use a
FileFieldin a form, you must also remember tobind the file data to the form.The
max_lengtherror refers to the length of the filename. In the errormessage for that key,%(max)dwill be replaced with the maximum filenamelength and%(length)dwill be replaced with the current filename length.- Default widget:
FilePathField¶
- class
FilePathField(**kwargs)[source]¶ - Default widget:
Select - Empty value:
None - Normalizes to: A unicode object
- 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 fiveextra arguments; only
pathis required:path¶The absolute path to the directory whose contents you want listed. Thisdirectory must exist.
recursive¶If
False(the default) only the direct contents ofpathwill beoffered as choices. IfTrue, the directory will be descended intorecursively and all descendants will be listed as choices.
match¶A regular expression pattern; only files with names matching this expressionwill be allowed as choices.
allow_files¶Optional. Either
TrueorFalse. Default isTrue. Specifieswhether files in the specified location should be included. Either this orallow_foldersmust beTrue.
allow_folders¶Optional. Either
TrueorFalse. Default isFalse. Specifieswhether folders in the specified location should be included. Either this orallow_filesmust beTrue.
- Default widget:
FloatField¶
- class
FloatField(**kwargs)[source]¶ - Default widget:
NumberInputwhenField.localizeisFalse, elseTextInput. - Empty value:
None - Normalizes to: A Python float.
- Validates that the given value is a float. Leading and trailingwhitespace is allowed, as in Python’s
float()function. - Error message keys:
required,invalid,max_value,min_value
Takes two optional arguments for validation,
max_valueandmin_value.These control the range of values permitted in the field.- Default widget:
ImageField¶
- class
ImageField(**kwargs)[source]¶ - Default widget:
ClearableFileInput - Empty value:
None - Normalizes to: An
UploadedFileobject that wraps the file contentand file name into a single object. - Validates that file data has been bound to the form, and that thefile is of an image format understood by Pillow.
- Error message keys:
required,invalid,missing,empty,invalid_image
Using an
ImageFieldrequires thatPillow is installed with supportfor the image formats you use. If you encounter acorruptimageerrorwhen you upload an image, it usually means that Pillow doesn’t understandits format. To fix this, install the appropriate library and reinstallPillow.When you use an
ImageFieldon a form, you must also remember tobind the file data to the form.After the field has been cleaned and validated, the
UploadedFileobject will have an additionalimageattribute containing the PillowImage instance used to check if the file was a valid image. Also,UploadedFile.content_typewill be updated with the image’s content typeif Pillow can determine it, otherwise it will be set toNone.- Default widget:
IntegerField¶
- class
IntegerField(**kwargs)[source]¶ - Default widget:
NumberInputwhenField.localizeisFalse, elseTextInput. - Empty value:
None - Normalizes to: A Python integer or long integer.
- Validates that the given value is an integer. Leading and trailingwhitespace is allowed, as in Python’s
int()function. - Error message keys:
required,invalid,max_value,min_value
The
max_valueandmin_valueerror messages may contain%(limit_value)s, which will be substituted by the appropriate limit.Takes two optional arguments for validation:
max_value¶
min_value¶
These control the range of values permitted in the field.
- Default widget:
GenericIPAddressField¶
- class
GenericIPAddressField(**kwargs)[source]¶ A field containing either an IPv4 or an IPv6 address.
- Default widget:
TextInput - Empty value:
''(an empty string) - Normalizes to: A Unicode object. IPv6 addresses arenormalized as described below.
- Validates that the given value is a valid IP address.
- Error message keys:
required,invalid
The IPv6 address normalization followsRFC 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::0:01would be normalized to2001::1, and::ffff:0a0a:0a0ato::ffff:10.10.10.10. All charactersare converted to lowercase.Takes two optional arguments:
protocol¶Limits valid inputs to the specified protocol.Accepted values are
both(default),IPv4orIPv6. 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 to192.0.2.1. Default is disabled. Can only be usedwhenprotocolis set to'both'.
- Default widget:
MultipleChoiceField¶
- class
MultipleChoiceField(**kwargs)[source]¶ - Default widget:
SelectMultiple - Empty value:
[](an empty list) - Normalizes to: A list of Unicode objects.
- Validates that every value in the given list of values exists in the listof choices.
- Error message keys:
required,invalid_choice,invalid_list
The
invalid_choiceerror message may contain%(value)s, which will bereplaced with the selected choice.Takes one extra required argument,
choices, as forChoiceField.- Default widget:
TypedMultipleChoiceField¶
- class
TypedMultipleChoiceField(**kwargs)[source]¶ Just like a
MultipleChoiceField, exceptTypedMultipleChoiceFieldtakes two extra arguments,coerceandempty_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
coerceargument. - Validates that the given values exists in the list of choices and can becoerced.
- Error message keys:
required,invalid_choice
The
invalid_choiceerror message may contain%(value)s, which will bereplaced with the selected choice.Takes two extra arguments,
coerceandempty_value, as forTypedChoiceField.- Default widget:
NullBooleanField¶
- class
NullBooleanField(**kwargs)[source]¶ - Default widget:
NullBooleanSelect - Empty value:
None - Normalizes to: A Python
True,FalseorNonevalue. - Validates nothing (i.e., it never raises a
ValidationError).
- Default widget:
RegexField¶
- class
RegexField(**kwargs)[source]¶ - Default widget:
TextInput - Empty value:
''(an empty string) - Normalizes to: A Unicode object.
- Validates that the given value matches against a certain regularexpression.
- Error message keys:
required,invalid
Takes one required argument:
regex¶A regular expression specified either as a string or a compiled regularexpression object.
Also takes
max_length,min_length, andstrip, which work justas they do forCharField.strip¶- New in Django 1.9.
Defaults to
False. If enabled, stripping will be applied before theregex validation.
- Default widget:
SlugField¶
- class
SlugField(**kwargs)[source]¶ - Default widget:
TextInput - Empty value:
''(an empty string) - Normalizes to: A Unicode object.
- Validates 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
SlugFieldin forms.Takes an optional parameter:
allow_unicode¶- New in Django 1.9.
A boolean instructing the field to accept Unicode letters in additionto ASCII letters. Defaults to
False.
- Default widget:
TimeField¶
- class
TimeField(**kwargs)[source]¶ - Default widget:
TextInput - Empty value:
None - Normalizes to: A Python
datetime.timeobject. - Validates that the given value is either a
datetime.timeor stringformatted in a particular time format. - Error message keys:
required,invalid
Takes one optional argument:
input_formats¶A list of formats used to attempt to convert a string to a valid
datetime.timeobject.
If no
input_formatsargument is provided, the default input formats are:'%H:%M:%S',# '14:30:59''%H:%M',# '14:30'
- Default widget:
URLField¶
- class
URLField(**kwargs)[source]¶ - Default widget:
URLInput - Empty value:
''(an empty string) - Normalizes to: A Unicode object.
- Validates that the given value is a valid URL.
- Error message keys:
required,invalid
Takes the following optional arguments:
max_length¶
min_length¶
These are the same as
CharField.max_lengthandCharField.min_length.- Default widget:
Slightly complex built-inField classes¶
ComboField¶
- class
ComboField(**kwargs)[source]¶ - Default widget:
TextInput - Empty value:
''(an empty string) - Normalizes to: A Unicode object.
- Validates the given value against each of the fields specifiedas 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 (inthe order in which they are provided).
>>>fromdjango.formsimportComboField>>>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).']
- Default widget:
MultiValueField¶
- class
MultiValueField(fields=(),**kwargs)[source]¶ - Default widget:
TextInput - Empty value:
''(an empty string) - Normalizes to: the type returned by the
compressmethod of the subclass. - Validates the given value against each of the fields specifiedas an argument to the
MultiValueField. - Error message keys:
required,invalid,incomplete
Aggregates the logic of multiple fields that together produce a singlevalue.
This field is abstract and must be subclassed. In contrast with thesingle-value fields, subclasses of
MultiValueFieldmust notimplementclean()but instead - implementcompress().Takes one extra required argument:
fields¶A tuple of fields whose values are cleaned and subsequently combinedinto a single value. Each value of the field is cleaned by thecorresponding field in
fields– the first value is cleaned by thefirst field, the second value is cleaned by the second field, etc.Once all fields are cleaned, the list of clean values is combined intoa single value bycompress().
Also takes one extra optional argument:
require_all_fields¶Defaults to
True, in which case arequiredvalidation errorwill be raised if no value is supplied for any field.When set to
False, theField.requiredattribute can be settoFalsefor individual fields to make them optional. If no valueis supplied for a required field, anincompletevalidation errorwill be raised.A default
incompleteerror message can be defined on theMultiValueFieldsubclass, or different messages can be definedon each individual field. For example:fromdjango.core.validatorsimportRegexValidatorclassPhoneField(MultiValueField):def__init__(self,*args,**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(PhoneField,self).__init__(error_messages=error_messages,fields=fields,require_all_fields=False,*args,**kwargs)
widget¶Must be a subclass of
django.forms.MultiWidget.Default value isTextInput, whichprobably is not very useful in this case.
compress(data_list)[source]¶Takes a list of valid values and returns a “compressed” version ofthose values – in a single value. For example,
SplitDateTimeFieldis a subclass which combines a time fieldand a date field into adatetimeobject.This method must be implemented in the subclasses.
- Default widget:
SplitDateTimeField¶
- class
SplitDateTimeField(**kwargs)[source]¶ - Default widget:
SplitDateTimeWidget - Empty value:
None - Normalizes to: A Python
datetime.datetimeobject. - Validates that the given value is a
datetime.datetimeor stringformatted 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.dateobject.
If no
input_date_formatsargument is provided, the default input formatsforDateFieldare used.input_time_formats¶A list of formats used to attempt to convert a string to a valid
datetime.timeobject.
If no
input_time_formatsargument is provided, the default input formatsforTimeFieldare used.- Default widget:
Fields which handle relationships¶
Two fields are available for representing relationships betweenmodels:ModelChoiceField andModelMultipleChoiceField. Both of these fields require asinglequeryset parameter that is used to create the choices forthe field. Upon form validation, these fields will place either onemodel object (in the case ofModelChoiceField) or multiple modelobjects (in the case ofModelMultipleChoiceField) into thecleaned_data dictionary of the form.
For more complex uses, you can specifyqueryset=None when declaring theform field and then populate thequeryset in the form’s__init__()method:
classFooMultipleChoiceForm(forms.Form):foo_select=forms.ModelMultipleChoiceField(queryset=None)def__init__(self,*args,**kwargs):super(FooMultipleChoiceForm,self).__init__(*args,**kwargs)self.fields['foo_select'].queryset=...
ModelChoiceField¶
- class
ModelChoiceField(**kwargs)[source]¶ - 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 aforeign key. Note that the default widget for
ModelChoiceFieldbecomesimpractical when the number of entries increases. You should avoid using itfor more than 100 items.A single argument is required:
queryset¶A
QuerySetof model objects from which the choices for thefield will be derived, and which will be used to validate theuser’s selection.
ModelChoiceFieldalso takes two optional arguments:empty_label¶By default the
<select>widget used byModelChoiceFieldwill have anempty choice at the top of the list. You can change the text of thislabel (which is"---------"by default) with theempty_labelattribute, or you can disable the empty label entirely by settingempty_labeltoNone:# A custom empty labelfield1=forms.ModelChoiceField(queryset=...,empty_label="(Nothing)")# No empty labelfield2=forms.ModelChoiceField(queryset=...,empty_label=None)
Note that if a
ModelChoiceFieldis required and has a defaultinitial value, no empty choice is created (regardless of the valueofempty_label).
to_field_name¶This optional argument is used to specify the field to use as the valueof the choices in the field’s widget. Be sure it’s a unique field forthe model, otherwise the selected value could match more than oneobject. By default it is set to
None, in which case the primary keyof each object will be used. For example:# No custom to_field_namefield1=forms.ModelChoiceField(queryset=...)
would yield:
<selectid="id_field1"name="field1"><optionvalue="obj1.pk">Object1</option><optionvalue="obj2.pk">Object2</option>...</select>
and:
# to_field_name providedfield2=forms.ModelChoiceField(queryset=...,to_field_name="name")
would yield:
<selectid="id_field2"name="field2"><optionvalue="obj1.name">Object1</option><optionvalue="obj2.name">Object2</option>...</select>
The
__str__(__unicode__on Python 2) method of the model will becalled to generate string representations of the objects for use in thefield’s choices; to provide customized representations, subclassModelChoiceFieldand overridelabel_from_instance. This method willreceive a model object, and should return a string suitable for representingit. For example:fromdjango.formsimportModelChoiceFieldclassMyModelChoiceField(ModelChoiceField):deflabel_from_instance(self,obj):return"My Object #%i"%obj.id
- Default widget:
ModelMultipleChoiceField¶
- class
ModelMultipleChoiceField(**kwargs)[source]¶ - Default widget:
SelectMultiple - Empty value: An empty
QuerySet(self.queryset.none()) - Normalizes to: A
QuerySetof model instances. - Validates that every id in the given list of values exists in thequeryset.
- Error message keys:
required,list,invalid_choice,invalid_pk_value
The
invalid_choicemessage may contain%(value)sand theinvalid_pk_valuemessage may contain%(pk)s, which will besubstituted by the appropriate values.Allows the selection of one or more model objects, suitable forrepresenting a many-to-many relation. As with
ModelChoiceField,you can uselabel_from_instanceto customize the objectrepresentations.A single argument is required:
queryset¶Same as
ModelChoiceField.queryset.
Takes one optional argument:
to_field_name¶Same as
ModelChoiceField.to_field_name.
- Default widget:
Creating custom fields¶
If the built-inField classes don’t meet your needs, you can easily createcustomField classes. To do this, just create a subclass ofdjango.forms.Field. Its only requirements are that it implement aclean() method and that its__init__() method accept the core argumentsmentioned above (required,label,initial,widget,help_text).
You can also customize how a field will be accessed by overridingget_bound_field().

