A Form instance is either bound to a set of data, or unbound.
If it’s bound to a set of data, it’s capable of validating that data\nand rendering the form as HTML with the data displayed in the HTML.
If it’s unbound, it cannot do validation (because there’s no data to\nvalidate!), but it can still render the blank form as HTML.
To create an unbound Form instance, instantiate the class:
>>> f = ContactForm()\nTo bind data to a form, pass the data as a dictionary as the first parameter to\nyour Form class constructor:
>>> data = {\n... "subject": "hello",\n... "message": "Hi there",\n... "sender": "foo@example.com",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data)\nIn this dictionary, the keys are the field names, which correspond to the\nattributes in your Form class. The values are the data you’re trying to\nvalidate. These will usually be strings, but there’s no requirement that they be\nstrings; the type of data you pass depends on the Field, as we’ll see\nin a moment.
If you need to distinguish between bound and unbound form instances at runtime,\ncheck the value of the form’s is_bound attribute:
>>> f = ContactForm()\n>>> f.is_bound\nFalse\n>>> f = ContactForm({"subject": "hello"})\n>>> f.is_bound\nTrue\nNote that passing an empty dictionary creates a bound form with empty data:
\n>>> f = ContactForm({})\n>>> f.is_bound\nTrue\nIf you have a bound Form instance and want to change the data somehow,\nor if you want to bind an unbound Form instance to some data, create\nanother Form instance. There is no way to change data in a\nForm instance. Once a Form instance has been created, you\nshould consider its data immutable, whether it has data or not.
Implement a clean() method on your Form when you must add custom\nvalidation for fields that are interdependent. See\nCleaning and validating fields that depend on each other for example usage.
The primary task of a Form object is to validate data. With a bound\nForm instance, call the is_valid() method to run validation\nand return a boolean designating whether the data was valid:
>>> data = {\n... "subject": "hello",\n... "message": "Hi there",\n... "sender": "foo@example.com",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data)\n>>> f.is_valid()\nTrue\nLet’s try with some invalid data. In this case, subject is blank (an error,\nbecause all fields are required by default) and sender is not a valid\nemail address:
>>> data = {\n... "subject": "",\n... "message": "Hi there",\n... "sender": "invalid email address",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data)\n>>> f.is_valid()\nFalse\nAccess the errors attribute to get a dictionary of error\nmessages:
>>> f.errors\n{'sender': ['Enter a valid email address.'], 'subject': ['This field is required.']}\nIn this dictionary, the keys are the field names, and the values are lists of\nstrings representing the error messages. The error messages are stored\nin lists because a field can have multiple error messages.
\nYou can access errors without having to call\nis_valid() first. The form’s data will be validated the first time\neither you call is_valid() or access errors.
The validation routines will only get called once, regardless of how many times\nyou access errors or call is_valid(). This means that\nif validation has side effects, those side effects will only be triggered once.
Returns a dict that maps fields to their original ValidationError\ninstances.
>>> f.errors.as_data()\n{'sender': [ValidationError(['Enter a valid email address.'])],\n'subject': [ValidationError(['This field is required.'])]}\nUse this method anytime you need to identify an error by its code. This\nenables things like rewriting the error’s message or writing custom logic in a\nview when a given error is present. It can also be used to serialize the errors\nin a custom format (e.g. XML); for instance, as_json()\nrelies on as_data().
The need for the as_data() method is due to backwards compatibility.\nPreviously ValidationError instances were lost as soon as their\nrendered error messages were added to the Form.errors dictionary.\nIdeally Form.errors would have stored ValidationError instances\nand methods with an as_ prefix could render them, but it had to be done\nthe other way around in order not to break code that expects rendered error\nmessages in Form.errors.
Returns the errors serialized as JSON.
\n>>> f.errors.as_json()\n{"sender": [{"message": "Enter a valid email address.", "code": "invalid"}],\n"subject": [{"message": "This field is required.", "code": "required"}]}\nBy default, as_json() does not escape its output. If you are using it for\nsomething like AJAX requests to a form view where the client interprets the\nresponse and inserts errors into the page, you’ll want to be sure to escape the\nresults on the client-side to avoid the possibility of a cross-site scripting\nattack. You can do this in JavaScript with element.textContent = errorText\nor with jQuery’s $(el).text(errorText) (rather than its .html()\nfunction).
If for some reason you don’t want to use client-side escaping, you can also\nset escape_html=True and error messages will be escaped so you can use them\ndirectly in HTML.
Returns the errors as a dictionary suitable for serializing to JSON.\nForm.errors.as_json() returns serialized JSON, while this returns the\nerror data before it’s serialized.
The escape_html parameter behaves as described in\nForm.errors.as_json().
This method allows adding errors to specific fields from within the\nForm.clean() method, or from outside the form altogether; for instance\nfrom a view.
The field argument is the name of the field to which the errors\nshould be added. If its value is None the error will be treated as\na non-field error as returned by Form.non_field_errors().
The error argument can be a string, or preferably an instance of\nValidationError. See Raising ValidationError for best practices\nwhen defining form errors.
Note that Form.add_error() automatically removes the relevant field from\ncleaned_data.
This method returns a boolean designating whether a field has an error with\na specific error code. If code is None, it will return True\nif the field contains any errors at all.
To check for non-field errors use\nNON_FIELD_ERRORS as the field parameter.
This method returns the list of errors from Form.errors that aren’t associated with a particular field.\nThis includes ValidationErrors that are raised in Form.clean() and errors added using Form.add_error(None,\n"...").
It’s meaningless to validate a form with no data, but, for the record, here’s\nwhat happens with unbound forms:
\n>>> f = ContactForm()\n>>> f.is_valid()\nFalse\n>>> f.errors\n{}\nUse initial to declare the initial value of form fields at\nruntime. For example, you might want to fill in a username field with the\nusername of the current session.
To accomplish this, use the initial argument to a Form.\nThis argument, if given, should be a dictionary mapping field names to initial\nvalues. Only include the fields for which you’re specifying an initial value;\nit’s not necessary to include every field in your form. For example:
>>> f = ContactForm(initial={"subject": "Hi there!"})\nThese values are only displayed for unbound forms, and they’re not used as\nfallback values if a particular value isn’t provided.
\nIf a Field defines initial and you\ninclude initial when instantiating the Form, then the latter\ninitial will have precedence. In this example, initial is provided both\nat the field level and at the form instance level, and the latter gets\nprecedence:
>>> from django import forms\n>>> class CommentForm(forms.Form):\n... name = forms.CharField(initial="class")\n... url = forms.URLField()\n... comment = forms.CharField()\n...\n>>> f = CommentForm(initial={"name": "instance"}, auto_id=False)\n>>> print(f)\n<div>Name:<input type="text" name="name" value="instance" required></div>\n<div>Url:<input type="url" name="url" required></div>\n<div>Comment:<input type="text" name="comment" required></div>\nReturns the initial data for a form field. It retrieves the data from\nForm.initial if present, otherwise trying Field.initial.\nCallable values are evaluated.
It is recommended to use BoundField.initial over\nget_initial_for_field() because BoundField.initial has a\nsimpler interface. Also, unlike get_initial_for_field(),\nBoundField.initial caches its values. This is useful especially when\ndealing with callables whose return values can change (e.g. datetime.now or\nuuid.uuid4):
>>> import uuid\n>>> class UUIDCommentForm(CommentForm):\n... identifier = forms.UUIDField(initial=uuid.uuid4)\n...\n>>> f = UUIDCommentForm()\n>>> f.get_initial_for_field(f.fields["identifier"], "identifier")\nUUID('972ca9e4-7bfe-4f5b-af7d-07b3aa306334')\n>>> f.get_initial_for_field(f.fields["identifier"], "identifier")\nUUID('1b411fab-844e-4dec-bd4f-e9b0495f04d0')\n>>> # Using BoundField.initial, for comparison\n>>> f["identifier"].initial\nUUID('28a09c59-5f00-4ed9-9179-a3b074fa9c30')\n>>> f["identifier"].initial\nUUID('28a09c59-5f00-4ed9-9179-a3b074fa9c30')\nUse the has_changed() method on your Form when you need to check if the\nform data has been changed from the initial data.
>>> data = {\n... "subject": "hello",\n... "message": "Hi there",\n... "sender": "foo@example.com",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data, initial=data)\n>>> f.has_changed()\nFalse\nWhen the form is submitted, we reconstruct it and provide the original data\nso that the comparison can be done:
\n>>> f = ContactForm(request.POST, initial=data)\n>>> f.has_changed()\nhas_changed() will be True if the data from request.POST differs\nfrom what was provided in initial or False otherwise. The\nresult is computed by calling Field.has_changed() for each field in the\nform.
The changed_data attribute returns a list of the names of the fields whose\nvalues in the form’s bound data (usually request.POST) differ from what was\nprovided in initial. It returns an empty list if no data differs.
>>> f = ContactForm(request.POST, initial=data)\n>>> if f.has_changed():\n... print("The following fields changed: %s" % ", ".join(f.changed_data))\n...\n>>> f.changed_data\n['subject', 'message']\nYou can access the fields of Form instance from its fields\nattribute:
>>> for row in f.fields.values():\n... print(row)\n...\n<django.forms.fields.CharField object at 0x7ffaac632510>\n<django.forms.fields.URLField object at 0x7ffaac632f90>\n<django.forms.fields.CharField object at 0x7ffaac3aa050>\n>>> f.fields["name"]\n<django.forms.fields.CharField object at 0x7ffaac6324d0>\nYou can alter the field and BoundField of Form instance to\nchange the way it is presented in the form:
>>> f.as_div().split("</div>")[0]\n'<div><label for="id_subject">Subject:</label><input type="text" name="subject" maxlength="100" required id="id_subject">'\n>>> f["subject"].label = "Topic"\n>>> f.as_div().split("</div>")[0]\n'<div><label for="id_subject">Topic:</label><input type="text" name="subject" maxlength="100" required id="id_subject">'\nBeware not to alter the base_fields attribute because this modification\nwill influence all subsequent ContactForm instances within the same Python\nprocess:
>>> f.base_fields["subject"].label_suffix = "?"\n>>> another_f = CommentForm(auto_id=False)\n>>> f.as_div().split("</div>")[0]\n'<div><label for="id_subject">Subject?</label><input type="text" name="subject" maxlength="100" required id="id_subject">'\nEach field in a Form class is responsible not only for validating\ndata, but also for “cleaning” it – normalizing it to a consistent format. This\nis a nice feature, because it allows data for a particular field to be input in\na variety of ways, always resulting in consistent output.
For example, DateField normalizes input into a\nPython datetime.date object. Regardless of whether you pass it a string in\nthe format '1994-07-15', a datetime.date object, or a number of other\nformats, DateField will always normalize it to a datetime.date object\nas long as it’s valid.
Once you’ve created a Form instance with a set of data and validated\nit, you can access the clean data via its cleaned_data attribute:
>>> data = {\n... "subject": "hello",\n... "message": "Hi there",\n... "sender": "foo@example.com",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data)\n>>> f.is_valid()\nTrue\n>>> f.cleaned_data\n{'cc_myself': True, 'message': 'Hi there', 'sender': 'foo@example.com', 'subject': 'hello'}\nNote that any text-based field – such as CharField or EmailField –\nalways cleans the input into a string. We’ll cover the encoding implications\nlater in this document.
If your data does not validate, the cleaned_data dictionary contains\nonly the valid fields:
>>> data = {\n... "subject": "",\n... "message": "Hi there",\n... "sender": "invalid email address",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data)\n>>> f.is_valid()\nFalse\n>>> f.cleaned_data\n{'cc_myself': True, 'message': 'Hi there'}\ncleaned_data will always only contain a key for fields defined in the\nForm, even if you pass extra data when you define the Form. In this\nexample, we pass a bunch of extra fields to the ContactForm constructor,\nbut cleaned_data contains only the form’s fields:
>>> data = {\n... "subject": "hello",\n... "message": "Hi there",\n... "sender": "foo@example.com",\n... "cc_myself": True,\n... "extra_field_1": "foo",\n... "extra_field_2": "bar",\n... "extra_field_3": "baz",\n... }\n>>> f = ContactForm(data)\n>>> f.is_valid()\nTrue\n>>> f.cleaned_data # Doesn't contain extra_field_1, etc.\n{'cc_myself': True, 'message': 'Hi there', 'sender': 'foo@example.com', 'subject': 'hello'}\nWhen the Form is valid, cleaned_data will include a key and value for\nall its fields, even if the data didn’t include a value for some optional\nfields. In this example, the data dictionary doesn’t include a value for the\nnick_name field, but cleaned_data includes it, with an empty value:
>>> from django import forms\n>>> class OptionalPersonForm(forms.Form):\n... first_name = forms.CharField()\n... last_name = forms.CharField()\n... nick_name = forms.CharField(required=False)\n...\n>>> data = {"first_name": "John", "last_name": "Lennon"}\n>>> f = OptionalPersonForm(data)\n>>> f.is_valid()\nTrue\n>>> f.cleaned_data\n{'nick_name': '', 'first_name': 'John', 'last_name': 'Lennon'}\nIn this above example, the cleaned_data value for nick_name is set to an\nempty string, because nick_name is CharField, and CharFields treat\nempty values as an empty string. Each field type knows what its “blank” value\nis – e.g., for DateField, it’s None instead of the empty string. For\nfull details on each field’s behavior in this case, see the “Empty value” note\nfor each field in the “Built-in Field classes” section below.
You can write code to perform validation for particular form fields (based on\ntheir name) or for the form as a whole (considering combinations of various\nfields). More information about this is in Form and field validation.
\nThe second task of a Form object is to render itself as HTML. To do so,\nprint it:
>>> f = ContactForm()\n>>> print(f)\n<div><label for="id_subject">Subject:</label><input type="text" name="subject" maxlength="100" required id="id_subject"></div>\n<div><label for="id_message">Message:</label><input type="text" name="message" required id="id_message"></div>\n<div><label for="id_sender">Sender:</label><input type="email" name="sender" required id="id_sender"></div>\n<div><label for="id_cc_myself">Cc myself:</label><input type="checkbox" name="cc_myself" id="id_cc_myself"></div>\nIf the form is bound to data, the HTML output will include that data\nappropriately. For example, if a field is represented by an\n<input type="text">, the data will be in the value attribute. If a\nfield is represented by an <input type="checkbox">, then that HTML will\ninclude checked if appropriate:
>>> data = {\n... "subject": "hello",\n... "message": "Hi there",\n... "sender": "foo@example.com",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data)\n>>> print(f)\n<div><label for="id_subject">Subject:</label><input type="text" name="subject" value="hello" maxlength="100" required id="id_subject"></div>\n<div><label for="id_message">Message:</label><input type="text" name="message" value="Hi there" required id="id_message"></div>\n<div><label for="id_sender">Sender:</label><input type="email" name="sender" value="foo@example.com" required id="id_sender"></div>\n<div><label for="id_cc_myself">Cc myself:</label><input type="checkbox" name="cc_myself" id="id_cc_myself" checked></div>\nThis default output wraps each field with a <div>. Notice the following:
For flexibility, the output does not include the <form> and </form>\ntags or an <input type="submit"> tag. It’s your job to do that.
Each field type has a default HTML representation. CharField is\nrepresented by an <input type="text"> and EmailField by an\n<input type="email">. BooleanField(null=False) is represented by an\n<input type="checkbox">. Note these are merely sensible defaults; you can\nspecify which HTML to use for a given field by using widgets, which we’ll\nexplain shortly.
The HTML name for each tag is taken directly from its attribute name\nin the ContactForm class.
The text label for each field – e.g. 'Subject:', 'Message:' and\n'Cc myself:' is generated from the field name by converting all\nunderscores to spaces and upper-casing the first letter. Again, note\nthese are merely sensible defaults; you can also specify labels manually.
Each text label is surrounded in an HTML <label> tag, which points\nto the appropriate form field via its id. Its id, in turn, is\ngenerated by prepending 'id_' to the field name. The id\nattributes and <label> tags are included in the output by default, to\nfollow best practices, but you can change that behavior.
The output uses HTML5 syntax, targeting <!DOCTYPE html>. For example,\nit uses boolean attributes such as checked rather than the XHTML style\nof checked='checked'.
Although <div> output is the default output style when you print a form\nyou can customize the output by using your own form template which can be set\nsite-wide, per-form, or per-instance. See Reusable form templates.
The default rendering when you print a form uses the following methods and\nattributes.
template_nameLink to this heading#The name of the template rendered if the form is cast into a string, e.g. via\nprint(form) or in a template via {{ form }}.
By default, a property returning the value of the renderer’s\nform_template_name. You may set it\nas a string template name in order to override that for a particular form\nclass.
render()Link to this heading#The render method is called by __str__ as well as the Form.as_div(),\nForm.as_table(), Form.as_p(), and Form.as_ul() methods.\nAll arguments are optional and default to:
template_name: Form.template_name
context: Value returned by Form.get_context()
renderer: Value returned by Form.default_renderer
By passing template_name you can customize the template used for just a\nsingle call.
get_context()Link to this heading#Return the template context for rendering the form.
\nThe available context is:
\nform: The bound form.
fields: All bound fields, except the hidden fields.
hidden_fields: All hidden bound fields.
errors: All non field related or hidden field related form errors.
template_name_labelLink to this heading#The template used to render a field’s <label>, used when calling\nBoundField.label_tag()/legend_tag(). Can be changed per\nform by overriding this attribute or more generally by overriding the default\ntemplate, see also Overriding built-in form templates.
The recommended approach for changing form output style is to set a custom form\ntemplate either site-wide, per-form, or per-instance. See\nReusable form templates for examples.
\nThe following helper functions are provided for backward compatibility and are\na proxy to Form.render() passing a particular template_name value.
Each helper pairs a form method with an attribute giving the appropriate\ntemplate name.
\nas_div()Link to this heading#The template used by as_div(). Default: 'django/forms/div.html'.
as_div() renders the form as a series of <div> elements, with each\n<div> containing one field, such as:
>>> f = ContactForm()\n>>> f.as_div()\n… gives HTML like:
\n<div>\n<label for="id_subject">Subject:</label>\n<input type="text" name="subject" maxlength="100" required id="id_subject">\n</div>\n<div>\n<label for="id_message">Message:</label>\n<input type="text" name="message" required id="id_message">\n</div>\n<div>\n<label for="id_sender">Sender:</label>\n<input type="email" name="sender" required id="id_sender">\n</div>\n<div>\n<label for="id_cc_myself">Cc myself:</label>\n<input type="checkbox" name="cc_myself" id="id_cc_myself">\n</div>\nas_p()Link to this heading#The template used by as_p(). Default: 'django/forms/p.html'.
as_p() renders the form as a series of <p> tags, with each <p>\ncontaining one field:
>>> f = ContactForm()\n>>> f.as_p()\n'<p><label for="id_subject">Subject:</label> <input id="id_subject" type="text" name="subject" maxlength="100" required></p>\\n<p><label for="id_message">Message:</label> <input type="text" name="message" id="id_message" required></p>\\n<p><label for="id_sender">Sender:</label> <input type="text" name="sender" id="id_sender" required></p>\\n<p><label for="id_cc_myself">Cc myself:</label> <input type="checkbox" name="cc_myself" id="id_cc_myself"></p>'\n>>> print(f.as_p())\n<p><label for="id_subject">Subject:</label> <input id="id_subject" type="text" name="subject" maxlength="100" required></p>\n<p><label for="id_message">Message:</label> <input type="text" name="message" id="id_message" required></p>\n<p><label for="id_sender">Sender:</label> <input type="email" name="sender" id="id_sender" required></p>\n<p><label for="id_cc_myself">Cc myself:</label> <input type="checkbox" name="cc_myself" id="id_cc_myself"></p>\nas_ul()Link to this heading#The template used by as_ul(). Default: 'django/forms/ul.html'.
as_ul() renders the form as a series of <li> tags, with each <li>\ncontaining one field. It does not include the <ul> or </ul>, so that\nyou can specify any HTML attributes on the <ul> for flexibility:
>>> f = ContactForm()\n>>> f.as_ul()\n'<li><label for="id_subject">Subject:</label> <input id="id_subject" type="text" name="subject" maxlength="100" required></li>\\n<li><label for="id_message">Message:</label> <input type="text" name="message" id="id_message" required></li>\\n<li><label for="id_sender">Sender:</label> <input type="email" name="sender" id="id_sender" required></li>\\n<li><label for="id_cc_myself">Cc myself:</label> <input type="checkbox" name="cc_myself" id="id_cc_myself"></li>'\n>>> print(f.as_ul())\n<li><label for="id_subject">Subject:</label> <input id="id_subject" type="text" name="subject" maxlength="100" required></li>\n<li><label for="id_message">Message:</label> <input type="text" name="message" id="id_message" required></li>\n<li><label for="id_sender">Sender:</label> <input type="email" name="sender" id="id_sender" required></li>\n<li><label for="id_cc_myself">Cc myself:</label> <input type="checkbox" name="cc_myself" id="id_cc_myself"></li>\nas_table()Link to this heading#The template used by as_table(). Default: 'django/forms/table.html'.
as_table() renders the form as an HTML <table>:
>>> f = ContactForm()\n>>> f.as_table()\n'<tr><th><label for="id_subject">Subject:</label></th><td><input id="id_subject" type="text" name="subject" maxlength="100" required></td></tr>\\n<tr><th><label for="id_message">Message:</label></th><td><input type="text" name="message" id="id_message" required></td></tr>\\n<tr><th><label for="id_sender">Sender:</label></th><td><input type="email" name="sender" id="id_sender" required></td></tr>\\n<tr><th><label for="id_cc_myself">Cc myself:</label></th><td><input type="checkbox" name="cc_myself" id="id_cc_myself"></td></tr>'\n>>> print(f)\n<tr><th><label for="id_subject">Subject:</label></th><td><input id="id_subject" type="text" name="subject" maxlength="100" required></td></tr>\n<tr><th><label for="id_message">Message:</label></th><td><input type="text" name="message" id="id_message" required></td></tr>\n<tr><th><label for="id_sender">Sender:</label></th><td><input type="email" name="sender" id="id_sender" required></td></tr>\n<tr><th><label for="id_cc_myself">Cc myself:</label></th><td><input type="checkbox" name="cc_myself" id="id_cc_myself"></td></tr>\nIt’s pretty common to style form rows and fields that are required or have\nerrors. For example, you might want to present required form rows in bold and\nhighlight errors in red.
\nThe Form class has a couple of hooks you can use to add class\nattributes to required rows or to rows with errors: set the\nForm.error_css_class and/or Form.required_css_class\nattributes:
from django import forms\n\n\nclass ContactForm(forms.Form):\n error_css_class = "error"\n required_css_class = "required"\n\n # ... and the rest of your fields here\nOnce you’ve done that, rows will be given "error" and/or "required"\nclasses, as needed. The HTML will look something like:
>>> f = ContactForm(data)\n>>> print(f)\n<div class="required"><label for="id_subject" class="required">Subject:</label> ...\n<div class="required"><label for="id_message" class="required">Message:</label> ...\n<div class="required"><label for="id_sender" class="required">Sender:</label> ...\n<div><label for="id_cc_myself">Cc myself:</label> ...\n>>> f["subject"].label_tag()\n<label class="required" for="id_subject">Subject:</label>\n>>> f["subject"].legend_tag()\n<legend class="required" for="id_subject">Subject:</legend>\n>>> f["subject"].label_tag(attrs={"class": "foo"})\n<label for="id_subject" class="foo required">Subject:</label>\n>>> f["subject"].legend_tag(attrs={"class": "foo"})\n<legend for="id_subject" class="foo required">Subject:</legend>\nSpecifies the renderer to use for the form. Defaults to\nNone which means to use the default renderer specified by the\nFORM_RENDERER setting.
You can set this as a class attribute when declaring your form or use the\nrenderer argument to Form.__init__(). For example:
from django import forms\n\n\nclass MyForm(forms.Form):\n default_renderer = MyRenderer()\nor:
\nform = MyForm(renderer=MyRenderer())\nIn the as_p(), as_ul() and as_table() shortcuts, the fields are\ndisplayed in the order in which you define them in your form class. For\nexample, in the ContactForm example, the fields are defined in the order\nsubject, message, sender, cc_myself. To reorder the HTML\noutput, change the order in which those fields are listed in the class.
There are several other ways to customize the order:
\nBy default Form.field_order=None, which retains the order in which you\ndefine the fields in your form class. If field_order is a list of field\nnames, the fields are ordered as specified by the list and remaining fields are\nappended according to the default order. Unknown field names in the list are\nignored. This makes it possible to disable a field in a subclass by setting it\nto None without having to redefine ordering.
You can also use the Form.field_order argument to a Form to\noverride the field order. If a Form defines\nfield_order and you include field_order when instantiating\nthe Form, then the latter field_order will have precedence.
You may rearrange the fields any time using order_fields() with a list of\nfield names as in field_order.
If you render a bound Form object, the act of rendering will automatically\nrun the form’s validation if it hasn’t already happened, and the HTML output\nwill include the validation errors as a <ul class="errorlist"> near the\nfield. The particular positioning of the error messages depends on the output\nmethod you’re using:
>>> data = {\n... "subject": "",\n... "message": "Hi there",\n... "sender": "invalid email address",\n... "cc_myself": True,\n... }\n>>> f = ContactForm(data, auto_id=False)\n>>> print(f)\n<div>Subject:\n <ul class="errorlist"><li>This field is required.</li></ul>\n <input type="text" name="subject" maxlength="100" required aria-invalid="true">\n</div>\n<div>Message:\n <textarea name="message" cols="40" rows="10" required>Hi there</textarea>\n</div>\n<div>Sender:\n <ul class="errorlist"><li>Enter a valid email address.</li></ul>\n <input type="email" name="sender" value="invalid email address" required aria-invalid="true">\n</div>\n<div>Cc myself:\n <input type="checkbox" name="cc_myself" checked>\n</div>\nBy default, forms use django.forms.utils.ErrorList to format validation\nerrors. ErrorList is a list like object where initlist is the\nlist of errors. In addition this class has the following attributes and\nmethods.
The CSS classes to be used when rendering the error list. Any provided\nclasses are added to the default errorlist class.
Specifies the renderer to use for ErrorList.\nDefaults to None which means to use the default renderer\nspecified by the FORM_RENDERER setting.
The name of the template used when calling __str__ or\nrender(). By default this is\n'django/forms/errors/list/default.html' which is a proxy for the\n'ul.html' template.
The name of the template used when calling as_text(). By default\nthis is 'django/forms/errors/list/text.html'. This template renders\nthe errors as a list of bullet points.
The name of the template used when calling as_ul(). By default\nthis is 'django/forms/errors/list/ul.html'. This template renders\nthe errors in <li> tags with a wrapping <ul> with the CSS\nclasses as defined by error_class.
Return context for rendering of errors in a template.
\nThe available context is:
\nerrors : A list of the errors.
error_class : A string of CSS classes.
The render method is called by __str__ as well as by the\nas_ul() method.
All arguments are optional and will default to:
\ntemplate_name: Value returned by template_name
context: Value returned by get_context()
renderer: Value returned by renderer
Renders the error list using the template defined by\ntemplate_name_text.
Renders the error list using the template defined by\ntemplate_name_ul.
If you’d like to customize the rendering of errors this can be achieved by\noverriding the template_name attribute or more generally by\noverriding the default template, see also\nOverriding built-in form templates.
The as_p(), as_ul(), and as_table() methods are shortcuts –\nthey’re not the only way a form object can be displayed.
Used to display HTML or access attributes for a single field of a\nForm instance.
The __str__() method of this object displays the HTML for this field.
To retrieve a single BoundField, use dictionary lookup syntax on your form\nusing the field’s name as the key:
>>> form = ContactForm()\n>>> print(form["subject"])\n<input id="id_subject" type="text" name="subject" maxlength="100" required>\nTo retrieve all BoundField objects, iterate the form:
>>> form = ContactForm()\n>>> for boundfield in form:\n... print(boundfield)\n...\n<input id="id_subject" type="text" name="subject" maxlength="100" required>\n<input type="text" name="message" id="id_message" required>\n<input type="email" name="sender" id="id_sender" required>\n<input type="checkbox" name="cc_myself" id="id_cc_myself">\nThe field-specific output honors the form object’s auto_id setting:
>>> f = ContactForm(auto_id=False)\n>>> print(f["message"])\n<input type="text" name="message" required>\n>>> f = ContactForm(auto_id="id_%s")\n>>> print(f["message"])\n<input type="text" name="message" id="id_message" required>\nBoundFieldLink to this heading#The HTML ID attribute for this BoundField. Returns an empty string\nif Form.auto_id is False.
This property returns the data for this BoundField\nextracted by the widget’s value_from_datadict()\nmethod, or None if it wasn’t given:
>>> unbound_form = ContactForm()\n>>> print(unbound_form["subject"].data)\nNone\n>>> bound_form = ContactForm(data={"subject": "My Subject"})\n>>> print(bound_form["subject"].data)\nMy Subject\nA list-like object that is displayed\nas an HTML <ul class="errorlist"> when printed:
>>> data = {"subject": "hi", "message": "", "sender": "", "cc_myself": ""}\n>>> f = ContactForm(data, auto_id=False)\n>>> print(f["message"])\n<input type="text" name="message" required aria-invalid="true">\n>>> f["message"].errors\n['This field is required.']\n>>> print(f["message"].errors)\n<ul class="errorlist"><li>This field is required.</li></ul>\n>>> f["subject"].errors\n[]\n>>> print(f["subject"].errors)\n\n>>> str(f["subject"].errors)\n''\nWhen rendering a field with errors, aria-invalid="true" will be set on\nthe field’s widget to indicate there is an error to screen reader users.
The form Field instance from the form class that\nthis BoundField wraps.
The Form instance this BoundField\nis bound to.
The help_text of the field.
The name that will be used in the widget’s HTML name attribute. It takes\nthe form prefix into account.
Use this property to render the ID of this field. For example, if you are\nmanually constructing a <label> in your template (despite the fact that\nlabel_tag()/legend_tag() will do this\nfor you):
<label for="{{ form.my_field.id_for_label }}">...</label>{{ my_field }}\nBy default, this will be the field’s name prefixed by id_\n(”id_my_field” for the example above). You may modify the ID by setting\nattrs on the field’s widget. For example,\ndeclaring a field like this:
my_field = forms.CharField(widget=forms.TextInput(attrs={"id": "myFIELD"}))\nand using the template above, would render something like:
\n<label for="myFIELD">...</label><input id="myFIELD" type="text" name="my_field" required>\nUse BoundField.initial to retrieve initial data for a form field.\nIt retrieves the data from Form.initial if present, otherwise\ntrying Field.initial. Callable values are evaluated. See\nInitial form values for more examples.
BoundField.initial caches its return value, which is useful\nespecially when dealing with callables whose return values can change (e.g.\ndatetime.now or uuid.uuid4):
>>> from datetime import datetime\n>>> class DatedCommentForm(CommentForm):\n... created = forms.DateTimeField(initial=datetime.now)\n...\n>>> f = DatedCommentForm()\n>>> f["created"].initial\ndatetime.datetime(2021, 7, 27, 9, 5, 54)\n>>> f["created"].initial\ndatetime.datetime(2021, 7, 27, 9, 5, 54)\nUsing BoundField.initial is recommended over\nget_initial_for_field().
Returns True if this BoundField’s widget is\nhidden.
The label of the field. This is used in\nlabel_tag()/legend_tag().
The name of this field in the form:
\n>>> f = ContactForm()\n>>> print(f["subject"].name)\nsubject\n>>> print(f["message"].name)\nmessage\nThe name of the template rendered with BoundField.as_field_group().
A property returning the value of the\ntemplate_name if set otherwise\nfield_template_name.
Returns the value of this BoundField widget’s use_fieldset attribute.
Returns the lowercased class name of the wrapped field’s widget, with any\ntrailing input or widget removed. This may be used when building\nforms where the layout is dependent upon the widget type. For example:
{% for field in form %}\n {% if field.widget_type == 'checkbox' %}\n # render one way\n {% else %}\n # render another way\n {% endif %}\n{% endfor %}\nBoundFieldLink to this heading#Renders the field using BoundField.render() with default values\nwhich renders the BoundField, including its label, help text and errors\nusing the template’s template_name if set\notherwise field_template_name
Returns a string of HTML for representing this as an <input type="hidden">.
**kwargs are passed to as_widget().
This method is primarily used internally. You should use a widget instead.
\nRenders the field by rendering the passed widget, adding any HTML\nattributes passed as attrs. If no widget is specified, then the\nfield’s default widget will be used.
only_initial is used by Django internals and should not be set\nexplicitly.
When you use Django’s rendering shortcuts, CSS classes are used to\nindicate required form fields or fields that contain errors. If you’re\nmanually rendering a form, you can access these CSS classes using the\ncss_classes method:
>>> f = ContactForm(data={"message": ""})\n>>> f["message"].css_classes()\n'required'\nIf you want to provide some additional classes in addition to the\nerror and required classes that may be required, you can provide\nthose classes as an argument:
\n>>> f = ContactForm(data={"message": ""})\n>>> f["message"].css_classes("foo bar")\n'foo bar required'\nReturn the template context for rendering the field. The available context\nis field being the instance of the bound field.
Renders a label tag for the form field using the template specified by\nForm.template_name_label.
The available context is:
\nfield: This instance of the BoundField.
contents: By default a concatenated string of\nBoundField.label and Form.label_suffix (or\nField.label_suffix, if set). This can be overridden by the\ncontents and label_suffix arguments.
attrs: A dict containing for,\nForm.required_css_class, and id. id is generated by the\nfield’s widget attrs or BoundField.auto_id. Additional\nattributes can be provided by the attrs argument.
use_tag: A boolean which is True if the label has an id.\nIf False the default template omits the tag.
tag: An optional string to customize the tag, defaults to label.
To separately render the label tag of a form field, you can call its\nlabel_tag() method:
>>> f = ContactForm(data={"message": ""})\n>>> print(f["message"].label_tag())\n<label for="id_message">Message:</label>\nIf you’d like to customize the rendering this can be achieved by overriding\nthe Form.template_name_label attribute or more generally by\noverriding the default template, see also\nOverriding built-in form templates.
Calls label_tag() with tag='legend' to render the label with\n<legend> tags. This is useful when rendering radio and multiple\ncheckbox widgets where <legend> may be more appropriate than a\n<label>.
The render method is called by as_field_group. All arguments are\noptional and default to:
template_name: BoundField.template_name
context: Value returned by BoundField.get_context()
renderer: Value returned by Form.default_renderer
By passing template_name you can customize the template used for just a\nsingle call.
Use this method to render the raw value of this field as it would be rendered\nby a Widget:
>>> initial = {"subject": "welcome"}\n>>> unbound_form = ContactForm(initial=initial)\n>>> bound_form = ContactForm(data={"subject": "hi"}, initial=initial)\n>>> print(unbound_form["subject"].value())\nwelcome\n>>> print(bound_form["subject"].value())\nhi\nBoundFieldLink to this heading#If you need to access some additional information about a form field in a\ntemplate and using a subclass of Field isn’t\nsufficient, consider also customizing BoundField.
A custom form field can override get_bound_field():
Takes an instance of Form and the name of the field.\nThe return value will be used when accessing the field in a template. Most\nlikely it will be an instance of a subclass of\nBoundField.
If you have a GPSCoordinatesField, for example, and want to be able to\naccess additional information about the coordinates in a template, this could\nbe implemented as follows:
class GPSCoordinatesBoundField(BoundField):\n @property\n def country(self):\n """\n Return the country the coordinates lie in or None if it can't be\n determined.\n """\n value = self.value()\n if value:\n return get_country_from_coordinates(value)\n else:\n return None\n\n\nclass GPSCoordinatesField(Field):\n def get_bound_field(self, form, field_name):\n return GPSCoordinatesBoundField(form, self, field_name)\nNow you can access the country in a template with\n{{ form.coordinates.country }}.
Dealing with forms that have FileField and ImageField fields\nis a little more complicated than a normal form.
Firstly, in order to upload files, you’ll need to make sure that your\n<form> element correctly defines the enctype as\n"multipart/form-data":
<form enctype="multipart/form-data" method="post" action="/foo/">\nSecondly, when you use the form, you need to bind the file data. File\ndata is handled separately to normal form data, so when your form\ncontains a FileField and ImageField, you will need to specify\na second argument when you bind your form. So if we extend our\nContactForm to include an ImageField called mugshot, we\nneed to bind the file data containing the mugshot image:
# Bound form with an image field\n>>> from django.core.files.uploadedfile import SimpleUploadedFile\n>>> data = {\n... "subject": "hello",\n... "message": "Hi there",\n... "sender": "foo@example.com",\n... "cc_myself": True,\n... }\n>>> file_data = {"mugshot": SimpleUploadedFile("face.jpg", b"file data")}\n>>> f = ContactFormWithMugshot(data, file_data)\nIn practice, you will usually specify request.FILES as the source\nof file data (just like you use request.POST as the source of\nform data):
# Bound form with an image field, data from the request\n>>> f = ContactFormWithMugshot(request.POST, request.FILES)\nConstructing an unbound form is the same as always – omit both form data and\nfile data:
\n# Unbound form with an image field\n>>> f = ContactFormWithMugshot()\nIf you’re writing reusable views or templates, you may not know ahead of time\nwhether your form is a multipart form or not. The is_multipart() method\ntells you whether the form requires multipart encoding for submission:
>>> f = ContactFormWithMugshot()\n>>> f.is_multipart()\nTrue\nHere’s an example of how you might use this in a template:
\n{% if form.is_multipart %}\n <form enctype="multipart/form-data" method="post" action="/foo/">\n{% else %}\n <form method="post" action="/foo/">\n{% endif %}\n{{ form }}\n</form>\nIf you have multiple Form classes that share fields, you can use\nsubclassing to remove redundancy.
When you subclass a custom Form class, the resulting subclass will\ninclude all fields of the parent class(es), followed by the fields you define\nin the subclass.
In this example, ContactFormWithPriority contains all the fields from\nContactForm, plus an additional field, priority. The ContactForm\nfields are ordered first:
>>> class ContactFormWithPriority(ContactForm):\n... priority = forms.CharField()\n...\n>>> f = ContactFormWithPriority(auto_id=False)\n>>> print(f)\n<div>Subject:<input type="text" name="subject" maxlength="100" required></div>\n<div>Message:<textarea name="message" cols="40" rows="10" required></textarea></div>\n<div>Sender:<input type="email" name="sender" required></div>\n<div>Cc myself:<input type="checkbox" name="cc_myself"></div>\n<div>Priority:<input type="text" name="priority" required></div>\nIt’s possible to subclass multiple forms, treating forms as mixins. In this\nexample, BeatleForm subclasses both PersonForm and InstrumentForm\n(in that order), and its field list includes the fields from the parent\nclasses:
>>> from django import forms\n>>> class PersonForm(forms.Form):\n... first_name = forms.CharField()\n... last_name = forms.CharField()\n...\n>>> class InstrumentForm(forms.Form):\n... instrument = forms.CharField()\n...\n>>> class BeatleForm(InstrumentForm, PersonForm):\n... haircut_type = forms.CharField()\n...\n>>> b = BeatleForm(auto_id=False)\n>>> print(b)\n<div>First name:<input type="text" name="first_name" required></div>\n<div>Last name:<input type="text" name="last_name" required></div>\n<div>Instrument:<input type="text" name="instrument" required></div>\n<div>Haircut type:<input type="text" name="haircut_type" required></div>\nIt’s possible to declaratively remove a Field inherited from a parent class\nby setting the name of the field to None on the subclass. For example:
>>> from django import forms\n\n>>> class ParentForm(forms.Form):\n... name = forms.CharField()\n... age = forms.IntegerField()\n...\n\n>>> class ChildForm(ParentForm):\n... name = None\n...\n\n>>> list(ChildForm().fields)\n['age']\nYou can put several Django forms inside one <form> tag. To give each\nForm its own namespace, use the prefix keyword argument:
>>> mother = PersonForm(prefix="mother")\n>>> father = PersonForm(prefix="father")\n>>> print(mother)\n<div><label for="id_mother-first_name">First name:</label><input type="text" name="mother-first_name" required id="id_mother-first_name"></div>\n<div><label for="id_mother-last_name">Last name:</label><input type="text" name="mother-last_name" required id="id_mother-last_name"></div>\n>>> print(father)\n<div><label for="id_father-first_name">First name:</label><input type="text" name="father-first_name" required id="id_father-first_name"></div>\n<div><label for="id_father-last_name">Last name:</label><input type="text" name="father-last_name" required id="id_father-last_name"></div>\nThe prefix can also be specified on the form class:
\n>>> class PersonForm(forms.Form):\n... ...\n... prefix = "person"\n...\n