Form processing generally has 3 paths:
Implementing this yourself often results in a lot of repeated boilerplate code (see Using a form in a view). To help avoid this, Django provides a collection of generic class-based views for form processing.
Given a simple contact form:
# forms.py
from django import forms
class ContactForm(forms.Form):
name = forms.CharField()
message = forms.CharField(widget=forms.Textarea)
def send_email(self):
# send email using the self.cleaned_data dictionary
pass
The view can be constructed using a FormView:
# views.py
from myapp.forms import ContactForm
from django.views.generic.edit import FormView
class ContactView(FormView):
template_name = 'contact.html'
form_class = ContactForm
success_url = '/thanks/'
def form_valid(self, form):
# This method is called when valid form data has been POSTed.
# It should return an HttpResponse.
form.send_email()
return super(ContactView, self).form_valid(form)
Notes:
TemplateResponseMixin so
template_name
can be used here.form_valid() simply
redirects to the success_url.Generic views really shine when working with models. These generic
views will automatically create a ModelForm, so long as
they can work out which model class to use:
model attribute is
given, that model class will be used.get_object()
returns an object, the class of that object will be used.queryset is
given, the model for that queryset will be used.Model form views provide a
form_valid() implementation
that saves the model automatically. You can override this if you have any
special requirements; see below for examples.
You don’t even need to provide a success_url for
CreateView or
UpdateView - they will use
get_absolute_url() on the model object if available.
If you want to use a custom ModelForm (for instance to
add extra validation) simply set
form_class on your view.
Note
When specifying a custom form class, you must still specify the model,
even though the form_class may
be a ModelForm.
First we need to add get_absolute_url() to our
Author class:
# models.py
from django.core.urlresolvers import reverse
from django.db import models
class Author(models.Model):
name = models.CharField(max_length=200)
def get_absolute_url(self):
return reverse('author-detail', kwargs={'pk': self.pk})
Then we can use CreateView and friends to do the actual
work. Notice how we’re just configuring the generic class-based views
here; we don’t have to write any logic ourselves:
# views.py
from django.views.generic.edit import CreateView, UpdateView, DeleteView
from django.core.urlresolvers import reverse_lazy
from myapp.models import Author
class AuthorCreate(CreateView):
model = Author
class AuthorUpdate(UpdateView):
model = Author
class AuthorDelete(DeleteView):
model = Author
success_url = reverse_lazy('author-list')
Note
We have to use reverse_lazy() here, not
just reverse as the urls are not loaded when the file is imported.
Finally, we hook these new views into the URLconf:
# urls.py
from django.conf.urls import patterns, url
from myapp.views import AuthorCreate, AuthorUpdate, AuthorDelete
urlpatterns = patterns('',
# ...
url(r'author/add/$', AuthorCreate.as_view(), name='author_add'),
url(r'author/(?P<pk>\d+)/$', AuthorUpdate.as_view(), name='author_update'),
url(r'author/(?P<pk>\d+)/delete/$', AuthorDelete.as_view(), name='author_delete'),
)
Note
These views inherit
SingleObjectTemplateResponseMixin
which uses
template_name_suffix
to construct the
template_name
based on the model.
In this example:
CreateView and UpdateView use myapp/author_form.htmlDeleteView uses myapp/author_confirm_delete.htmlIf you wish to have separate templates for CreateView and
UpdateView, you can set either
template_name or
template_name_suffix
on your view class.
To track the user that created an object using a CreateView,
you can use a custom ModelForm to do this. First, add
the foreign key relation to the model:
# models.py
from django.contrib.auth.models import User
from django.db import models
class Author(models.Model):
name = models.CharField(max_length=200)
created_by = models.ForeignKey(User)
# ...
Create a custom ModelForm in order to exclude the
created_by field and prevent the user from editing it:
# forms.py
from django import forms
from myapp.models import Author
class AuthorForm(forms.ModelForm):
class Meta:
model = Author
exclude = ('created_by',)
In the view, use the custom
form_class and override
form_valid() to add the
user:
# views.py
from django.views.generic.edit import CreateView
from myapp.models import Author
from myapp.forms import AuthorForm
class AuthorCreate(CreateView):
form_class = AuthorForm
model = Author
def form_valid(self, form):
form.instance.created_by = self.request.user
return super(AuthorCreate, self).form_valid(form)
Note that you’ll need to decorate this
view using
login_required(), or
alternatively handle unauthorized users in the
form_valid().
Here is a simple example showing how you might go about implementing a form that works for AJAX requests as well as ‘normal’ form POSTs:
import json
from django.http import HttpResponse
from django.views.generic.edit import CreateView
class AjaxableResponseMixin(object):
"""
Mixin to add AJAX support to a form.
Must be used with an object-based FormView (e.g. CreateView)
"""
def render_to_json_response(self, context, **response_kwargs):
data = json.dumps(context)
response_kwargs['content_type'] = 'application/json'
return HttpResponse(data, **response_kwargs)
def form_invalid(self, form):
response = super(AjaxableResponseMixin, self).form_invalid(form)
if self.request.is_ajax():
return self.render_to_json_response(form.errors, status=400)
else:
return response
def form_valid(self, form):
# We make sure to call the parent's form_valid() method because
# it might do some processing (in the case of CreateView, it will
# call form.save() for example).
response = super(AjaxableResponseMixin, self).form_valid(form)
if self.request.is_ajax():
data = {
'pk': self.object.pk,
}
return self.render_to_json_response(data)
else:
return response
class AuthorCreate(AjaxableResponseMixin, CreateView):
model = Author
Apr 12, 2017