post_save signal with sender AUTH_USER_MODEL fires at login - django

Question

What was done
I have a custom User model called MyUser as it is described in an full example for an custom user model on the docs and a so called UserProfile that is connected to MyUser by an One-to-one relationship like it's described in the Django documentation about how to extend an existing user model.
In the documentation for Customizing authentication is an example for how to connect a post_save signal with the existing User model.
By following this, I put an testing receiver in a signals.py that is loaded by my apps.py file, like it's described in this SO answer.
Configuration
signal.py
def post_save_receiver(sender, instance, created, **kwargs):
send_mail('Testing', "Just testing...", 'hell#earth.tld', ['admin#heaven.tld'], fail_silently=False)
post_save.connect(post_save_receiver, sender=settings.AUTH_USER_MODEL)
models.py
class MyUserManager(BaseUserManager):
def create_user(self, email, password=None):
"""
Creates and saves a User with the given email and password.
"""
if not email:
raise ValueError('Users must have an email address')
user = self.model(
email=self.normalize_email(email),
)
user.set_password(password)
user.save(using=self._db)
return user
def create_superuser(self, email, password):
"""
Creates and saves a superuser with the given email and password.
"""
user = self.create_user(email,
password=password,
)
user.is_admin = True
user.save(using=self._db)
return user
class MyUser(AbstractBaseUser):
email = models.EmailField(
verbose_name='email address',
max_length=255,
unique=True,
)
is_active = models.BooleanField(default=True)
is_admin = models.BooleanField(default=False)
objects = MyUserManager()
USERNAME_FIELD = 'email'
def get_full_name(self):
# The user is identified by their email address
return self.email
def get_short_name(self):
# The user is identified by their email address
return self.email
def __str__(self): # __unicode__ on Python 2
return self.email
def has_perm(self, perm, obj=None):
"Does the user have a specific permission?"
# Simplest possible answer: Yes, always
return True
def has_module_perms(self, app_label):
"Does the user have permissions to view the app `app_label`?"
# Simplest possible answer: Yes, always
return True
#property
def is_staff(self):
"Is the user a member of staff?"
# Simplest possible answer: All admins are staff
return self.is_admin
views.py
def UserLogin(request):
if request.user.is_authenticated():
return HttpResponseRedirect("http://www.heaven.tld/account")
else:
if request.method == 'POST':
form = UserLoginForm(request.POST)
if form.is_valid():
username = form.cleaned_data['username']
password = form.cleaned_data['password']
user = authenticate(username=username, password=password)
if user is not None and user.is_active:
login(request, user)
return HttpResponseRedirect("http://www.heaven.tld/account")
else:
error_msg = 'Please try again!'
return render(request, "development",
{'form':form,
'error_msg':error_msg,
})
else:
error_msg = "Please try again!"
return render(request, "development",
{'form':form,
'error_msg':error_msg,
})
else:
form = UserLoginForm()
return render(request, "development", {'form': form})
The Problem
Now if I log in I always get this mail, but I want it only if a user was created.

Answer 1

Logging in causes the last_login timestamp to be updated, which triggers a save.
As others have stated, you just need to use the created parameter, which your signal receives but you currently ignore.

Answer 2

try:
def post_save_receiver(sender, instance, created, **kwargs):
if created:
send_mail('Testing', "Just testing...", 'hell#earth.tld', ['admin#heaven.tld'], fail_silently=False)
post_save.connect(post_save_receiver, sender=settings.AUTH_USER_MODEL)

Answer 3

I can't understand what will be saved when you login. You can use ipdb to trace it. By the way, if you set the created condition before send_mail function, the problem should be resolved.
if created:
send_mail(...)