使用django添加用户时自动生成用户名

from django.contrib.auth.models import AbstractUser
from django.db import models
from django.db.models.signals import post_save
from django.dispatch import receiver
import random
import string

class CustomUser(AbstractUser):
    generated_username = models.CharField(max_length=255, blank=True)

@receiver(post_save, sender=CustomUser)
def generate_username(sender, instance, created, **kwargs):
    if created and not instance.generated_username:
        # 生成用户名的逻辑
        generated_username = generate_random_username()
        instance.generated_username = generated_username
        instance.save()

def generate_random_username():
    # 生成随机用户名的逻辑
    random_string = ''.join(random.choices(string.ascii_lowercase + string.digits, k=8))
    return f"user_{random_string}"