Django using custom signals to send mail

Question

In my sample, signal function was created in models.py.Instead of this,i think it is possible to do using custom signals concept.

my models.py for signals function is

class Book(models.Model):
    [..........]

def send_update(sender, instance, created, **kwargs):
    if instance.author_name:
        message = "Book is updated"
        subject = "Updates"
        send_mail(subject, message, your_email,
            [instance.email,])

post_save.connect(send_update, sender=Book)

views.py is

if request.POST:
        form = BookForm(request.POST)

        if form.is_valid():
            cd = form.cleaned_data
            form.save()
            return redirect('/index/')
    return render_to_response('addbook.html',{ 'form':form },context_instance=RequestContext(request))

Instead of this how can we create a custom signals using signals.py file to send the mail.

I am trying to learn this in practical,an example will help me to do that.

Thanks

Answer 1

signals.py

from django.db.models.signals import post_save
from app.models import Book

def send_update(sender, instance, created, **kwargs):
    if instance.author_name:
        message = "Book is updated"
        subject = "Updates"
        send_mail(subject, message, your_email,
            [instance.email,])

post_save.connect(send_update, sender=Book)

Register the signals by importing it in the app's __init__.py file. This will allow to import models from signals.py.

__init__.py

import signals

Answer 2

Define your signal and receiver in signals.py:

from django.dispatch import Signal

post_update = Signal(providing_args = ['instance'])

def send_update(...):
    ....

post_update.connect(send_update, sender = Book)

In views.py, send the signal right after you save the form:

instance = form.save()
post_update.send(sender = Book, instance = instance)