old_contents: 
  from django.db import models
  from django.contrib.auth.models import User
  from django.db.models.signals import post_save
  
  
  class UserProfile(models.Model):
      user = models.OneToOneField(User)
      #other fields here
      home_adress = models.CharField(max_length=200)
  
      def __str__(self):
          return "%s's profile" % self.user
  
  
  def create_user_profile(sender, instance, created, **kwargs):
      if created:
          profile, created = UserProfile.objects.get_or_create(user=instance)
  
  
  post_save.connect(create_user_profile, sender=User)
  
  
new_contents: 
  from django.db import models
  from django.contrib.auth.models import User
  from django.db.models.signals import post_save
  
  
  class UserProfile(models.Model):
      user = models.OneToOneField(User)
      #other fields here
      home_adress = models.CharField(max_length=200)
  
      def __str__(self):
          return "%s's profile" % self.user
  
  
  class ICalURL(models.Model):
      user = models.ForeignKey(UserProfile)
      name = models.CharField(max_length=50)
      url = models.CharField(max_length=400)
  
      def __str__(self):
          return "%s's profile" % self.user
  
  
  def create_user_profile(sender, instance, created, **kwargs):
      if created:
          profile, created = UserProfile.objects.get_or_create(user=instance)
  
  
  post_save.connect(create_user_profile, sender=User)
  
  
subject: Add iCalURL to UserProfile