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 contact form:
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:
from myapp.forms import ContactForm
from django.views.generic.edit import FormView
class ContactFormView(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().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), set
form_class on your view.
تبصره
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:
from django.db import models
from django.urls import reverse
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:
from django.urls import reverse_lazy
from django.views.generic.edit import CreateView, DeleteView, UpdateView
from myapp.models import Author
class AuthorCreateView(CreateView):
model = Author
fields = ['name']
class AuthorUpdateView(UpdateView):
model = Author
fields = ['name']
class AuthorDeleteView(DeleteView):
model = Author
success_url = reverse_lazy('author-list')
تبصره
We have to use reverse_lazy() instead of
reverse(), as the urls are not loaded when the file is imported.
The fields attribute works the same way as the fields attribute on the
inner Meta class on ModelForm. Unless you define the
form class in another way, the attribute is required and the view will raise
an ImproperlyConfigured exception if it’s not.
If you specify both the fields
and form_class attributes, an
ImproperlyConfigured exception will be raised.
Finally, we hook these new views into the URLconf:
from django.urls import path
from myapp.views import AuthorCreateView, AuthorDeleteView, AuthorUpdateView
urlpatterns = [
# ...
path('author/add/', AuthorCreateView.as_view(), name='author-add'),
path('author/<int:pk>/', AuthorUpdateView.as_view(), name='author-update'),
path('author/<int:pk>/delete/', AuthorDeleteView.as_view(), name='author-delete'),
]
تبصره
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.
request.user¶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:
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, on_delete=models.CASCADE)
# ...
In the view, ensure that you don’t include created_by in the list of fields
to edit, and override
form_valid() to add the user:
from django.contrib.auth.mixins import LoginRequiredMixin
from django.views.generic.edit import CreateView
from myapp.models import Author
class AuthorCreateView(LoginRequiredMixin, CreateView):
model = Author
fields = ['name']
def form_valid(self, form):
form.instance.created_by = self.request.user
return super().form_valid(form)
LoginRequiredMixin prevents users who
aren’t logged in from accessing the form. If you omit that, you’ll need to
handle unauthorized users in form_valid().
Here is an example showing how you might go about implementing a form that works with an API-based workflow as well as ‘normal’ form POSTs:
from django.http import JsonResponse
from django.views.generic.edit import CreateView
from myapp.models import Author
class JsonableResponseMixin:
"""
Mixin to add JSON support to a form.
Must be used with an object-based FormView (e.g. CreateView)
"""
def form_invalid(self, form):
response = super().form_invalid(form)
if self.request.accepts('text/html'):
return response
else:
return JsonResponse(form.errors, status=400)
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().form_valid(form)
if self.request.accepts('text/html'):
return response
else:
data = {
'pk': self.object.pk,
}
return JsonResponse(data)
class AuthorCreateView(JsonableResponseMixin, CreateView):
model = Author
fields = ['name']
Jul 27, 2022