django display message after POST form submit - django

Question

I have a page with a POST form, that have a action set to some url.
i.e assume this page url is /form_url/ :
..
The view in /submit_url/ take care of the form data. After this, I want to return the same page of the form with a success message.
In the view that take care for the POST form, I use HttpResponseRedirect, in order to "clear" the form data from the browser.
But in this way I can't display a message in the form page, unless I do something like:
return HttpResponseRedirect("/form_url/?success=1")
and then check for this parameter in the template. I don't like this way, since if the user refreshes the page, he will still see the success message.
I've noticed that in django admin site, the delete/add of objects does use redirect after POST submit, and still display a success message somehow.
How?
I've already briefly seen django "messaging" app, but I want to know how it work first..

Answer 1

The django admin uses django.contrib.messages, you use it like this:
In your view:
from django.contrib import messages
def my_view(request):
...
if form.is_valid():
....
messages.success(request, 'Form submission successful')
And in your templates:
{% if messages %}
<ul class="messages">
{% for message in messages %}
<li {% if message.tags %} class=" {{ message.tags }} " {% endif %}> {{ message }} </li>
{% endfor %}
</ul>
{% endif %}

Answer 2

For Class Based Views use self.request
I also use self.request.path_info in my return
from django.contrib import messages
class MyCreateView(CreateView):
...
def form_valid(self, form):
....
self.object.save()
messages.success(self.request, 'Form submission successful')
return HttpResponseRedirect(self.request.path_info)
Same template as damio's answer:
{% if messages %}
<ul class="messages">
{% for message in messages %}
<li {% if message.tags %} class=" {{ message.tags }} " {% endif %}> {{ message }} </li>
{% endfor %}
</ul>
{% endif %}

Answer 3

from django.contrib.messages.views import SuccessMessageMixin
from django.views.generic.edit import CreateView
from myapp.models import Author
class AuthorCreate(SuccessMessageMixin, CreateView):
model = Author
success_url = '/success/'
success_message = "%(name)s was created successfully"
https://docs.djangoproject.com/en/1.11/ref/contrib/messages/

Answer 4

You don't need to do a redirect to clear the form data. All you need to do is re-instantiate the form:
def your_view(request):
form = YourForm(request.POST or None)
success = False
if request.method == 'POST':
if form.is_valid():
form.save()
form = YourForm()
success = True
return render(request, 'your_template.html', {'form': form})
If the user refreshes the page, they're going to initiate a GET request, and success will be False. Either way, the form will be unbound on a GET, or on a successful POST.
If you leverage the messages framework, you'll still need to add a conditional in the template to display the messages if they exist or not.

Answer 5

Django messages framework stores the messages in the session or cookie (it depends on the storage backend).

Answer 6

If you're using a classed based view with django forms, and granted you've got the messages.html template set up, you can simply pass the 'SuccessMessageMixin' into your view like below
class YourView(SuccessMessageMixin,View):
success_message = 'your message_here'
This will display your message upon form success