wish/utils/models.py

from django.db import models
from django.contrib.auth.models import AbstractUser

# https://docs.djangoproject.com/en/3.1/topics/auth/customizing/#using-a-custom-user-model-when-starting-a-project
class MyUser(AbstractUser):
	
	def __str__(self):
		if self.first_name != '' and self.last_name != '':
			return f"{self.first_name} {self.last_name}"
		# Hack: if a nickname is to be used, it is the first name.
		if self.first_name != '':
			return self.first_name
		return self.username