Django execute custom code after user signup - django

Question

I have a users app in a Django project (version 2.1 and python 3.6). After an user signup (both front end and when added in the admin dashboard ideally), I'd like to insert data in one other table. I know how to insert data, but I didn't find out how to do it right after a successfull signup.
Ideal answer would just show me how to do something like print('hello') right after an user created his account.
# users/admin.py
from django.contrib import admin
from django.contrib.auth import get_user_model
from django.contrib.auth.admin import UserAdmin
from .forms import CustomUserCreationForm, CustomUserChangeForm
from .models import CustomUser
class CustomUserAdmin(UserAdmin):
add_form = CustomUserCreationForm
form = CustomUserChangeForm
model = CustomUser
list_display = ['email', 'username',]
admin.site.register(CustomUser, CustomUserAdmin)
# users/forms.py
from django import forms
from django.contrib.auth.forms import UserCreationForm, UserChangeForm
from .models import CustomUser
class CustomUserCreationForm(UserCreationForm):
class Meta(UserCreationForm):
model = CustomUser
fields = ('username', 'email')
class CustomUserChangeForm(UserChangeForm):
class Meta:
model = CustomUser
fields = ('username', 'email')
# users/models.py
from django.contrib.auth.models import AbstractUser
from django.db import models
class CustomUser(AbstractUser):
# add additional fields in here
credit = models.IntegerField(default=200) # editable=False
def __str__(self):
return self.email
# users/urls.py
from django.urls import path
from . import views
urlpatterns = [
path('signup/', views.SignUp.as_view(), name='signup'),
]
# users/views.py
from django.urls import reverse_lazy
from django.views import generic
from .forms import CustomUserCreationForm
class SignUp(generic.CreateView):
form_class = CustomUserCreationForm
success_url = reverse_lazy('login')
template_name = 'signup.html'

Answer 1

Use a post-save signal
https://docs.djangoproject.com/en/2.1/ref/signals/
from django.db.models.signals import post_save
from django.dispatch import receiver
#receiver(post_save, sender=User)
def say_hello(sender, instance, **kwargs):
if instate._state.adding:
print('hello')
Signal is better than a method on the view because the User may be created some way other than through the view e.g , via the shell, a management command, a migration, a different view, etc.
Note the _state is not "private" so don't feel bad about using it, it's just named that way to avoid clashing with field names.
Check _state instead of more common checking instance.pk because instance.pk is always present when primary key is a natural key rather than AutoField

Answer 2

I think the best approach would be overriding save method of CustomUser model. For example:
class CustomUser(AbstructUser):
def save(self, *args, **kwargs):
user = super(CustomUser, self).save(*args, **kwargs)
print("Hello World")
return user
Check here in Django documentation for more details: https://docs.djangoproject.com/en/2.1/topics/db/models/#overriding-predefined-model-methods.