mirror of
https://github.com/django/django.git
synced 2024-11-18 07:26:04 +00:00
87da9cd759
git-svn-id: http://code.djangoproject.com/svn/django/trunk@8904 bcc190cf-cafb-0310-a4f2-bffc1f526a37
260 lines
9.6 KiB
Plaintext
260 lines
9.6 KiB
Plaintext
.. _topics-forms-index:
|
|
|
|
==================
|
|
Working with forms
|
|
==================
|
|
|
|
.. admonition:: About this document
|
|
|
|
This document provides an introduction to Django's form handling features.
|
|
For a more detailed look at the forms API, see :ref:`ref-forms-api`. For
|
|
documentation of the available field types, see :ref:`ref-forms-fields`.
|
|
|
|
``django.forms`` is Django's form-handling library.
|
|
|
|
While it is possible to process form submissions just using Django's
|
|
:class:`~django.http.HttpRequest` class, using the form library takes care of a
|
|
number of common form-related tasks. Using it, you can:
|
|
|
|
1. Display an HTML form with automatically generated form widgets.
|
|
2. Checking submitted data against a set of validation rules.
|
|
3. Redisplaying a form in the case of validation errors.
|
|
4. Converting submitted form data to the relevant Python data types.
|
|
|
|
Overview
|
|
========
|
|
|
|
The library deals with these concepts:
|
|
|
|
.. glossary::
|
|
|
|
Widget
|
|
A class that corresponds to an HTML form widget, e.g.
|
|
``<input type="text">`` or ``<textarea>``. This handles rendering of the
|
|
widget as HTML.
|
|
|
|
Field
|
|
A class that is responsible for doing validation, e.g.
|
|
an ``EmailField`` that makes sure its data is a valid e-mail address.
|
|
|
|
Form
|
|
A collection of fields that knows how to validate itself and
|
|
display itself as HTML.
|
|
|
|
Form Media
|
|
The CSS and JavaScript resources that are required to render a form.
|
|
|
|
The library is decoupled from the other Django components, such as the database
|
|
layer, views and templates. It relies only on Django settings, a couple of
|
|
``django.utils`` helper functions and Django's internationalization hooks (but
|
|
you're not required to be using internationalization features to use this
|
|
library).
|
|
|
|
Form objects
|
|
============
|
|
|
|
A Form object encapsulates a sequence of form fields and a collection of
|
|
validation rules that must be fulfilled in order for the form to be accepted.
|
|
Form classes are created as subclasses of ``django.forms.Form`` and are
|
|
make use of a declarative style that you'll be familiar with if you've used
|
|
Django's database models.
|
|
|
|
For example, consider a form used to implement "contact me" functionality on a
|
|
personal Web site::
|
|
|
|
from django import forms
|
|
|
|
class ContactForm(forms.Form):
|
|
subject = forms.CharField(max_length=100)
|
|
message = forms.CharField()
|
|
sender = forms.EmailField()
|
|
cc_myself = forms.BooleanField(required=False)
|
|
|
|
A form is composed of ``Field`` objects. In this case, our form has four
|
|
fields: ``subject``, ``message``, ``sender`` and ``cc_myself``. ``CharField``,
|
|
``EmailField`` and ``BooleanField`` are just three of the available field types;
|
|
a full list can be found in :ref:`ref-forms-fields`.
|
|
|
|
If your form is going to be used to directly add or edit a Django model, you can
|
|
use a :ref:`ModelForm <topics-forms-modelforms>` to avoid duplicating your model
|
|
description.
|
|
|
|
Using a form in a view
|
|
----------------------
|
|
|
|
The standard pattern for processing a form in a view looks like this::
|
|
|
|
def contact(request):
|
|
if request.method == 'POST': # If the form has been submitted...
|
|
form = ContactForm(request.POST) # A form bound to the POST data
|
|
if form.is_valid(): # All validation rules pass
|
|
# Process the data in form.cleaned_data
|
|
# ...
|
|
return HttpResponseRedirect('/thanks/') # Redirect after POST
|
|
else:
|
|
form = ContactForm() # An unbound form
|
|
|
|
return render_to_response('contact.html', {
|
|
'form': form,
|
|
})
|
|
|
|
|
|
There are three code paths here:
|
|
|
|
1. If the form has not been submitted, an unbound instance of ContactForm is
|
|
created and passed to the template.
|
|
2. If the form has been submitted, a bound instance of the form is created
|
|
using ``request.POST``. If the submitted data is valid, it is processed
|
|
and the user is re-directed to a "thanks" page.
|
|
3. If the form has been submitted but is invalid, the bound form instance is
|
|
passed on to the template.
|
|
|
|
.. versionchanged:: 1.0
|
|
The ``cleaned_data`` attribute was called ``clean_data`` in earlier releases.
|
|
|
|
The distinction between **bound** and **unbound** forms is important. An unbound
|
|
form does not have any data associated with it; when rendered to the user, it
|
|
will be empty or will contain default values. A bound form does have submitted
|
|
data, and hence can be used to tell if that data is valid. If an invalid bound
|
|
form is rendered it can include inline error messages telling the user where
|
|
they went wrong.
|
|
|
|
See :ref:`ref-forms-api-bound-unbound` for further information on the
|
|
differences between bound and unbound forms.
|
|
|
|
Processing the data from a form
|
|
-------------------------------
|
|
|
|
Once ``is_valid()`` returns ``True``, you can process the form submission safe
|
|
in the knowledge that it conforms to the validation rules defined by your form.
|
|
While you could access ``request.POST`` directly at this point, it is better to
|
|
access ``form.cleaned_data``. This data has not only been validated but will
|
|
also be converted in to the relevant Python types for you. In the above example,
|
|
``cc_myself`` will be a boolean value. Likewise, fields such as ``IntegerField``
|
|
and ``FloatField`` convert values to a Python int and float respectively.
|
|
|
|
Extending the above example, here's how the form data could be processed::
|
|
|
|
if form.is_valid():
|
|
subject = form.cleaned_data['subject']
|
|
message = form.cleaned_data['message']
|
|
sender = form.cleaned_data['sender']
|
|
cc_myself = form.cleaned_data['cc_myself']
|
|
|
|
recipients = ['info@example.com']
|
|
if cc_myself:
|
|
recipients.append(sender)
|
|
|
|
from django.core.mail import send_mail
|
|
send_mail(subject, message, sender, recipients)
|
|
return HttpResponseRedirect('/thanks/') # Redirect after POST
|
|
|
|
For more on sending e-mail from Django, see :ref:`topics-email`.
|
|
|
|
Displaying a form using a template
|
|
----------------------------------
|
|
|
|
Forms are designed to work with the Django template language. In the above
|
|
example, we passed our ``ContactForm`` instance to the template using the
|
|
context variable ``form``. Here's a simple example template::
|
|
|
|
<form action="/contact/" method="POST">
|
|
{{ form.as_p }}
|
|
<input type="submit" value="Submit">
|
|
</form>
|
|
|
|
The form only outputs its own fields; it is up to you to provide the surrounding
|
|
``<form>`` tags and the submit button.
|
|
|
|
``form.as_p`` will output the form with each form field and accompanying label
|
|
wrapped in a paragraph. Here's the output for our example template::
|
|
|
|
<form action="/contact/" method="POST">
|
|
<p><label for="id_subject">Subject:</label>
|
|
<input id="id_subject" type="text" name="subject" maxlength="100" /></p>
|
|
<p><label for="id_message">Message:</label>
|
|
<input type="text" name="message" id="id_message" /></p>
|
|
<p><label for="id_sender">Sender:</label>
|
|
<input type="text" name="sender" id="id_sender" /></p>
|
|
<p><label for="id_cc_myself">Cc myself:</label>
|
|
<input type="checkbox" name="cc_myself" id="id_cc_myself" /></p>
|
|
<input type="submit" value="Submit">
|
|
</form>
|
|
|
|
Note that each form field has an ID attribute set to ``id_<field-name>``, which
|
|
is referenced by the accompanying label tag. This is important for ensuring
|
|
forms are accessible to assistive technology such as screen reader software. You
|
|
can also :ref:`customize the way in which labels and ids are generated
|
|
<ref-forms-api-configuring-label>`.
|
|
|
|
You can also use ``form.as_table`` to output table rows (you'll need to provide
|
|
your own ``<table>`` tags) and ``form.as_ul`` to output list items.
|
|
|
|
Customizing the form template
|
|
-----------------------------
|
|
|
|
If the default generated HTML is not to your taste, you can completely customize
|
|
the way a form is presented using the Django template language. Extending the
|
|
above example::
|
|
|
|
<form action="/contact/" method="POST">
|
|
<div class="fieldWrapper">
|
|
{{ form.subject.errors }}
|
|
<label for="id_subject">E-mail subject:</label>
|
|
{{ form.subject }}
|
|
</div>
|
|
<div class="fieldWrapper">
|
|
{{ form.message.errors }}
|
|
<label for="id_message">Your message:</label>
|
|
{{ form.message }}
|
|
</div>
|
|
<div class="fieldWrapper">
|
|
{{ form.sender.errors }}
|
|
<label for="id_sender">Your email address:</label>
|
|
{{ form.sender }}
|
|
</div>
|
|
<div class="fieldWrapper">
|
|
{{ form.cc_myself.errors }}
|
|
<label for="id_cc_myself">CC yourself?</label>
|
|
{{ form.cc_myself }}
|
|
</div>
|
|
<p><input type="submit" value="Send message"></p>
|
|
</form>
|
|
|
|
Each named form-field can be output to the template using
|
|
``{{ form.name_of_field }}``, which will produce the HTML needed to display the
|
|
form widget. Using ``{{ form.name_of_field.errors }}`` displays a list of form
|
|
errors, rendered as an unordered list. This might look like::
|
|
|
|
<ul class="errorlist">
|
|
<li>Sender is required.</li>
|
|
</ul>
|
|
|
|
The list has a CSS class of ``errorlist`` to allow you to style its appearance.
|
|
If you wish to further customize the display of errors you can do so by looping
|
|
over them::
|
|
|
|
{% if form.subject.errors %}
|
|
<ol>
|
|
{% for error in form.message.errors %}
|
|
<li><strong>{{ error|escape }}</strong></li>
|
|
{% endfor %}
|
|
</ol>
|
|
{% endif %}
|
|
|
|
Further topics
|
|
==============
|
|
|
|
This covers the basics, but forms can do a whole lot more:
|
|
|
|
.. toctree::
|
|
:maxdepth: 1
|
|
|
|
modelforms
|
|
formsets
|
|
media
|
|
|
|
.. seealso::
|
|
|
|
The :ref:`form API reference <ref-forms-index>`.
|