Form fields¶
When you create a new Form
, the most important part is defining its fields.
Each field has custom validation logic, along with a few other hooks.
Although the primary way you’ll use a Field
is in a Form
, 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 throws a forms.ValidationError
or returns the clean value:
var f = forms.EmailField()
print(f.clean('foo@example.com'))
// => foo@example.com
try {
f.clean('invalid email address')
}
catch (e) {
print(e.messages())
}
// => ["Enter a valid email address."]
Core field arguments¶
required¶
By default, each Field
assumes the value is required, so if you pass
an empty value – undefined
, null
or the empty string (''
) – then
clean()
will throw a ValidationError
.
To specify that a field is not required, pass required: false
to the
Field
constructor:
var f = forms.CharField({required: false})
If a Field
has required: false
and you pass clean()
an empty value,
then clean()
will return a normalised empty value rather than throwing a
ValidationError
. For CharField
, this will be an empty string.
For another Field
type, it might be null
(This varies from field to
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
.
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 initial option.
widget¶
The widget
argument lets you specify a Widget
to use when rendering this
Field
. You can pass either an instance or a Widget constructor. See
Widgets for more information.
helpText¶
The helpText
argument lets you specify descriptive text for this Field. If
you provide helpText
, it will be displayed next to the Field when the Field
is rendered by one the default rending components.
To render raw HTML in help text, specify it using the React convention for raw
HTML, which is as an object with an __html
property.
errorMessages¶
The errorMessages
argument lets you override the default messages that the
field will throw. Pass in an object with properties matching the error messages
you want to override. For example, here is the default error message:
var generic = forms.CharField()
try {
generic.clean('')
}
catch (e) {
print(e.messages())
}
// => ["This field is required."]
And here is a custom error message:
var name = forms.CharField({errorMessages: {required: 'Please enter your name.'}})
try {
name.clean('')
}
catch (e) {
print(e.messages())
}
// => ["Please enter your name."]
The error message codes used by fields are defined below.
validators¶
The validators
argument lets you provide a list of additional validation
functions for this field.
widgetAttrs¶
New in version 0.11.
The widgetAttrs
argument lets you specify additional attributes for the
field’s Widget without having to specify a new Widget from scratch using the
widget
argument.
This provides a more convenient way to add attributes like autoFocus
,
className
or data-
attributes to the field’s default Widget but has
the lowest priority when determining final widget attributes.
For example, you can’t override an Input
-based widget’s type
attribute
using widgetAttrs
, as type
is set in that widget’s render()
method
based on the specific widget constructor being used.
However, TextInput()
treats the type
attribute specially, to allow
you to override the rendered type when creating an instance:
TextInput({attrs: {type: 'tel'}})
Or you can extend TextInput
to create your own widget constructor:
var TelInput = TextInput.extend({
inputType: 'tel'
})
Providing choices¶
Fields and Widgets which take a choices
argument expect to be given a list
containing any of the following:
- Choice pairs
A choice pair is a list containing exactly 2 elements, which correspond to:
- the value to be submitted/returned when the choice is selected.
- the value to be displayed to the user for selection.
For example:
var STATE_CHOICES = [ ['S', 'Scoped'] , ['D', 'Defined'] , ['P', 'In-Progress'] , ['C', 'Completed'] , ['A', 'Accepted'] ] print(reactHTML(forms.Select().render('state', null, {choices: STATE_CHOICES}))) /* => <select name="state"> <option value="S">Scoped</option> <option value="D">Defined</option> <option value="P">In-Progress</option> <option value="C">Completed</option> <option value="A">Accepted</option> </select> */
- Grouped lists of choice pairs
A list containing exactly 2 elements, which correspond to:
- A group label
- A list of choice pairs, as described above
var DRINK_CHOICES = [ ['Cheap', [ [1, 'White Lightning'] , [2, 'Buckfast'] , [3, 'Tesco Gin'] ] ] , ['Expensive', [ [4, 'Vieille Bon Secours Ale'] , [5, 'Château d’Yquem'] , [6, 'Armand de Brignac Midas'] ] ] , [7, 'Beer'] ] print(reactHTML(forms.Select().render('drink', null, {choices: DRINK_CHOICES}))) /* => <select name="drink"> <optgroup label="Cheap"> <option value="1">White Lightning</option> <option value="2">Buckfast</option> <option value="3">Tesco Gin</option> </optgroup> <optgroup label="Expensive"> <option value="4">Vieille Bon Secours Ale</option> <option value="5">Château d’Yquem</option> <option value="6">Armand de Brignac Midas</option> </optgroup> <option value="7">Beer</option> </select> */
As you can see from the 'Beer'
example above, grouped pairs can be mixed
with ungrouped pairs within the list of choices.
- Flat choices
New in version 0.5.
If a non-array value is provided where newforms expects to see a choice pair, it will be normalised to a choice pair using the same value for submission and display.
This allows you to pass a flat list of choices when that’s all you need:
var VOWEL_CHOICES = ['A', 'E', 'I', 'O', 'U'] var f = forms.ChoiceField({choices: VOWEL_CHOICES}) print(f.choices()) // => [['A', 'A'], ['E', 'E'], ['I', 'I'], ['O', 'O'], ['U', 'U']] var ARBITRARY_CHOICES = [ ['Numbers', [1, 2,]] , ['Letters', ['A', 'B']] ] f.setChoices(ARBITRARY_CHOICES) print(f.choices()) // => [['Numbers', [[1, 1], [2, 2]]], ['Letters', [['A', 'A'], ['B', 'B']]]]
Dynamic choices¶
A common pattern for providing dynamic choices (or indeed, dynamic anything) is
to provide your own form constructor and pass in whatever data is required to
make changes to form.fields
as the form is being instantiated.
Newforms provides a util.makeChoices()
helper function for creating
choice pairs from a list of objects using named properties:
var ProjectBookingForm = forms.Form.extend({
project: forms.ChoiceField(),
hours: forms.DecimalField({minValue: 0, maxValue: 24, maxdigits: 4, decimalPlaces: 2}),
date: forms.DateField(),
constructor: function(projects, kwargs) {
// Call the constructor of whichever form you're extending so that the
// forms.Form constructor eventually gets called - this.fields doesn't
// exist until this happens.
forms.Form.call(this, kwargs)
// Now that this.fields is a thing, make whatever changes you need to -
// in this case, we're going to creata a list of pairs of project ids
// and names to set as the project field's choices.
this.fields.project.setChoices(forms.util.makeChoices(projects, 'id', 'name'))
}
})
var projects = [
{id: 1, name: 'Project 1'}
, {id: 2, name: 'Project 2'}
, {id: 3, name: 'Project 3'}
]
var form = new ProjectBookingForm(projects, {autoId: false})
print(reactHTML((form.boundField('project').render()))
/* =>
<select name=\"project\">
<option value=\"1\">Project 1</option>
<option value=\"2\">Project 2</option>
<option value=\"3\">Project 3</option>
</select>
*/
Server-side example of using a form with dynamic choices:
// Users are assigned to projects and they're booking time, so we need to:
// 1. Display choices for the projects they're assigned to
// 2. Validate that the submitted project id is one they've been assigned to
var form
var display = function() { res.render('book_time', {form: form}) }
req.user.getProjects(function(err, projects) {
if (err) { return next(err) }
if (req.method == 'POST') {
form = new ProjectBookingForm(projects, {data: req.body})
if (form.isValid()) {
return ProjectService.saveHours(user, form.cleanedData, function(err) {
if (err) { return next(err) }
return res.redirect('/time/book/')
})
}
}
else {
form = new ProjectBookingForm(projects)
}
display(form)
})
Built-in Field types¶
newforms comes with a set of Field
types that represent common validation
eeds. 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).
Built-in Field type hierarchy¶
- Field
- BaseTemporalField
- BooleanField
- CharField
- ChoiceField
- ComboField
- IntegerField
- FileField
- MultiValueField
Build-in Fields (A-Z)¶
BooleanField()
¶
- Default widget:
CheckboxInput()
- Empty value:
false
- Normalises to: A JavaScript
true
orfalse
value.- Validates that the value is
true
(e.g. the check box is checked) if the field hasrequired: true
.- Error message keys:
required
Note
Since all
Field
types haverequired: true
by default, the validation condition here is important. If you want to include a boolean in your form that can be eithertrue
orfalse
(e.g. a checked or unchecked checkbox), you must remember to pass inrequired: false
when creating theBooleanField
.
CharField()
¶
- Default widget:
TextInput()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates
maxLength
orminLength
, if they are provided. Otherwise, all inputs are valid.- Error message keys:
required
,maxLength
,minLength
Has two optional arguments for validation:
- maxLength
- minLength
If provided, these arguments ensure that the string is at most or at least the given length.
ChoiceField()
¶
- Default widget:
Select()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates that the given value exists in the list of choices.
- Error message keys:
required
,invalidChoice
The
invalidChoice
error message may contain{value}
, which will be replaced with the selected choice.Takes one extra argument:
choices
A list of pairs (2 item lists) to use as choices for this field. See Providing choices for more details.
TypedChoiceField()
¶
Just like a
ChoiceField()
, exceptTypedChoiceField()
takes two extra arguments,coerce
andemptyValue
.
- Default widget:
Select()
- Empty value: Whatever you’ve given as
emptyValue
- Normalises 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
,invalidChoice
Takes extra arguments:
coerce
A function that takes one argument and returns a coerced value. Examples include the built-in
Number
,Boolean
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 inchoices
.emptyValue
The value to use to represent “empty.” Defaults to the empty string;
null
is another common choice here. Note that this value will not be coerced by the function given in thecoerce
argument, so choose it accordingly.
DateField()
¶
- Default widget:
DateInput()
- Empty value:
null
- Normalises to: A JavaScript
Date
object, with its time fields set to zero.- Validates that the given value is either a
Date
, or string formatted in a particular date format.- Error message keys:
required
,invalid
Takes one optional argument:
inputFormats
A list of format strings used to attempt to convert a string to a valid
Date
object.If no
inputFormats
argument is provided, the default input formats are:[ '%Y-%m-%d' // '2006-10-25' , '%m/%d/%Y', '%m/%d/%y' // '10/25/2006', '10/25/06' , '%b %d %Y', '%b %d, %Y' // 'Oct 25 2006', 'Oct 25, 2006' , '%d %b %Y', '%d %b, %Y' // '25 Oct 2006', '25 Oct, 2006' , '%B %d %Y', '%B %d, %Y' // 'October 25 2006', 'October 25, 2006' , '%d %B %Y', '%d %B, %Y' // '25 October 2006', '25 October, 2006' ]
DateTimeField()
¶
- Default widget:
DateTimeInput()
- Empty value:
null
- Normalises to: A JavaScript
Date
object.- Validates that the given value is either a
Date
or string formatted in a particular datetime format.- Error message keys:
required
,invalid
Takes one optional argument:
inputFormats
A list of format strings used to attempt to convert a string to a valid
Date
object.If no
inputFormats
argument 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' ]
DecimalField()
¶
- Default widget:
NumberInput()
.- Empty value:
null
- Normalises to: A string (since JavaScript doesn’t have built-in Decimal type).
- Validates that the given value is a decimal. Leading and trailing whitespace is ignored.
- Error message keys:
required
,invalid
,maxValue
,minValue
,maxDigits
,maxDecimalPlaces
,maxWholeDigits
The
maxValue
andminValue
error messages may contain{limitValue}
, which will be substituted by the appropriate limit.Similarly, the
maxDigits
,maxDecimalPlaces
andmaxWholeDigits
error messages may contain{max}
.Takes four optional arguments:
maxValue
minValue
These control the range of values permitted in the field.
maxDigits
The maximum number of digits (those before the decimal point plus those after the decimal point, with leading zeros stripped) permitted in the value.
decimalDlaces
The maximum number of decimal places permitted.
EmailField()
¶
- Default widget:
EmailInput()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates that the given value is a valid email address, using a moderately complex regular expression.
- Error message keys:
required
,invalid
Has two optional arguments for validation,
maxLength
andminLength
. If provided, these arguments ensure that the string is at most or at least the given length.
FileField()
¶
- Default widget:
ClearableFileInput()
- Empty value:
null
- Normalises to:
- Client: a native File object, when supported by the browser, otherwise the
value
of the<input type="file">
.- Server: the given object in
files
- this field just validates what’s there and leaves the rest up to you.- Can validate that non-empty file data has been bound to the form.
- Error message keys:
required
,invalid
,missing
,empty
,maxLength
Has two optional arguments for validation,
maxLength
andallowEmptyFile
. 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.When you use a
FileField
in a form, you must also remember to bind the file data to the form.The
maxLength
error refers to the length of the filename. In the error message for that key,{max}
will be replaced with the maximum filename length and{length}
will be replaced with the current filename length.
FilePathField()
¶
- Default widget:
Select()
- Empty value:
null
- Normalises to: A string
- Validates that the selected choice exists in the list of choices.
- Error message keys:
required
,invalidChoice
The field allows choosing from files inside a certain directory. It takes three 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 ofpath
will be offered as choices. Iftrue
, 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.
allowFiles
Optional. Either
true
orfalse
. Default istrue
. Specifies whether files in the specified location should be included. Either this orallowFolders
must betrue
.allowFolders
Optional. Either
true
orfalse
. Default isfalse
. Specifies whether folders in the specified location should be included. Either this orallowFiles
must betrue
.
FloatField()
¶
- Default widget:
NumberInput()
.- Empty value:
null
- Normalises to: A JavaScript
Number
.- Validates that the given value is a float. Leading and trailing whitespace is allowed.
- Error message keys:
required
,invalid
,maxValue
,minValue
Takes two optional arguments for validation,
maxValue
andminValue
. These control the range of values permitted in the field.
ImageField()
¶
- Default widget:
ClearableFileInput()
- Empty value:
null
- Normalises to: The given object in
files
- this field just validates what’s there and leaves the rest up to you.- Validates that file data has been bound to the form, and that the file is of an image format.
- Error message keys:
required
,invalid
,missing
,empty
,invalidImage
Note
Server-side image validation isn’t implemented yet.
When you use a
ImageField
in a form, you must also remember to bind the file data to the form.
IntegerField()
¶
- Default widget:
NumberInput()
.- Empty value:
null
- Normalises to: A JavaScript
Number
.- Validates that the given value is an integer. Leading and trailing whitespace is allowed.
- Error message keys:
required
,invalid
,maxValue
,minValue
The
maxValue
andminValue
error messages may contain{limitValue}
, which will be substituted by the appropriate limit.Takes two optional arguments for validation:
maxValue
minValue
These control the range of values permitted in the field.
IPAddressField()
¶
Deprecated since version 0.5: This field has been deprecated in favour of
GenericIPAddressField()
.
- Default widget:
TextInput()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates that the given value is a valid IPv4 address, using a regular expression.
- Error message keys:
required
,invalid
GenericIPAddressField()
¶
A field containing either an IPv4 or an IPv6 address.
- Default widget:
TextInput()
- Empty value:
''
(an empty string)- Normalises to: A string. IPv6 addresses are normalised as described below.
- Validates that the given value is a valid IP address.
- Error message keys:
required
,invalid
The IPv6 address normalisation 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 normalised to2001::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
oripv6
. Matching is case insensitive.unpackIPv4
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 used whenprotocol
is set to'both'
.
MultipleChoiceField()
¶
- Default widget:
SelectMultiple()
- Empty value:
[]
(an empty list)- Normalises 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
,invalidChoice
,invalidList
The
invalidChoice
error message may contain{value}
, which will be replaced with the selected choice.Takes one extra required argument,
choices
, as forChoiceField
.
MultipleFileField()
¶
-
New in version 0.11:
Default widget:
FileInput()
withmultiple
attributeEmpty value:
[]
(an empty list)Normalises to:
- Client: a list of File objects, when supported by the browser,
otherwise the
value
of the<input type="file" multiple>
. - Server: the given object in
files
- this field just validates what’s there and leaves the rest up to you.
- Client: a list of File objects, when supported by the browser,
otherwise the
Can validate that non-empty file data has been bound to the form.
Error message keys:
required
,invalid
,missing
,empty
,maxLength
The empty
and maxLength
error messages may contain {name}
, which
will be replaced with the name of the file which failed validation.
Has two optional arguments for validation, maxLength
and
allowEmptyFile
as for FileField
.
TypedMultipleChoiceField()
¶
Just like a
MultipleChoiceField()
, exceptTypedMultipleChoiceField()
takes two extra arguments,coerce
andemptyValue
.
- Default widget:
SelectMultiple()
- Empty value: Whatever you’ve given as
emptyValue
- Normalises 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
,invalidChoice
The
invalidChoice
error message may contain{value}
, which will be replaced with the selected choice.Takes two extra arguments,
coerce
andemptyValue
, as forTypedChoiceField
.
NullBooleanField()
¶
- Default widget:
NullBooleanSelect()
- Empty value:
null
- Normalises to: A JavaScript
true
,false
ornull
value.- Validates nothing (i.e., it never raises a
ValidationError
).
RegexField()
¶
- Default widget:
TextInput()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates that the given value matches against 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 takesmaxLength
andminLength
, which work just as they do forCharField
.
SlugField()
¶
- Default widget:
TextInput()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates that the given value contains only letters, numbers, underscores, and hyphens.
- Error messages:
required
,invalid
TimeField()
¶
- Default widget:
TextInput()
- Empty value:
null
- Normalises to: A JavaScript
Date
object, with its date fields set to 1900-01-01.- Validates that the given value is either a
Date
or string formatted in a particular time format.- Error message keys:
required
,invalid
Takes one optional argument:
inputFormats
A list of format strings used to attempt to convert a string to a valid
Date
object.If no
inputFormats
argument is provided, the default input formats are:[ '%H:%M:%S' // '14:30:59' , '%H:%M' // '14:30' ]
URLField()
¶
- Default widget:
URLInput()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates that the given value is a valid URL.
- Error message keys:
required
,invalid
Takes the following optional arguments:
- maxLength
- minLength
These are the same as
CharField.maxLength
andCharField.minLength
.
Slightly complex built-in Field
types¶
ComboField()
¶
- Default widget:
TextInput()
- Empty value:
''
(an empty string)- Normalises to: A string.
- Validates that the given value against each of the fields specified as an argument to the
ComboField
.- Error message keys:
required
,invalid
Takes one extra argument:
fields
The list of fields that should be used to validate the field’s value (in the order in which they are provided):
var f = forms.ComboField({fields: [ forms.CharField({maxLength: 20}), forms.EmailField() ]}) print(f.clean('test@example.com')) // => test@example.com try { f.clean('longemailaddress@example.com') } catch (e) { print(e.messages()) } // => ['Ensure this value has at most 20 characters (it has 28).']
MultiValueField()
¶
- Default widget:
TextInput()
- Empty value:
''
(an empty string)- Normalises to: the type returned by the
compress
method of the field.- Validates that 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 extended. In contrast with the single-value fields, fields which extend js:class:MultiValueField must not implement
BaseField#clean()
but instead - implementcompress()
.Takes one extra argument:
fields
A list 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 bycompress()
.Also takes one extra optional argument:
requireAllFields
New in version 0.5.
Defaults to
true
, in which case arequired
validation error will be raised if no value is supplied for any field.When set to
false
, theField.required
attribute can be set tofalse
for individual fields to make them optional. If no value is supplied for a required field, anincomplete
validation error will be raised.A default
incomplete
error message can be defined on theMultiValueField()
, or different messages can be defined on each individual field. For example:var RegexValidator = forms.validators.RegexValidator var PhoneField = forms.MultiValueField.extend({ constructor: function(kwargs) { kwargs = kwargs || {} // Define one message for all fields kwargs.errorMessages = { incomplete: 'Enter a country code and phone number.' } // Or define a different message for each field kwargs.fields = [ forms.CharField({errorMessages: {incomplete: 'Enter a country code.'}, validators: [ RegexValidator({regex: /^\d+$/, message: 'Enter a valid country code.'}) ]}), forms.CharField({errorMessages: {incomplete: 'Enter a phone number.'}, validators: [ RegexValidator({regex: /^\d+$/, message: 'Enter a valid phone number.'}) ]}), forms.CharField({required: false, validators: [ RegexValidator({regex: /^\d+$/, message: 'Enter a valid extension.'}) ]}) ] PhoneField.__super__.constructor.call(this, kwargs) } })MultiValueField.widget
Must extend
MultiWidget()
. Default value isTextInput()
, which probably is not very useful in this case. Have a nice day :)compress(dataList)
Takes a list of valid values and returns a “compressed” version of those values – in a single value. For example,
SplitDateTimeField()
is a combines a time field and a date field into aDate
object.This method must be implemented in the Field extending MultiValueField.
SplitDateTimeField()
¶
- Default widget:
SplitDateTimeWidget()
- Empty value:
null
- Normalises to: A JavaScript
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
,invalidDate
,invalidTime
Takes two optional arguments:
inputDateFormats
A list of format strings used to attempt to convert a string to a valid
Date
object with its time fields set to zero.If noinputDateFormats
argument is provided, the default input formats forDateField
are used.
inputTimeFormats
A list of format strings used to attempt to convert a string to a valid
Date
object with its date fields set to 1900-01-01.If noinputTimeFormats
argument is provided, the default input formats forTimeField
are used.
Creating custom fields¶
If the built-in Field
objects don’t meet your needs, you can easily create
custom Field
s. To do this, just .extend()
Field
. Its only
requirements are that it implement a clean()
method and that its
constructor()
accepts the core arguments mentioned above
(required
, label
, initial
, widget
, helpText
) in an argument
object.