Python 无法在django admin中添加slug，使用pre_save或save（）管理表单会引发错误

我一直试图在django的post模型中添加一个slug字段。对于slug字段，我想使用一个独特的slug函数，我一直在尝试使用信号和覆盖save方法来运行它，但是在这两种情况下，表单在表单中更改之前在管理页面中失效。当slug为空或其不唯一时，该表单无效

我的模特

from django.db import models
from django.utils import timezone
from django.contrib.auth.models import User
from .utils import unique_slug_generator


class Post(models.Model):
    post_type = models.CharField(max_length=100, default='npc')
    title = models.CharField(max_length=100)
    slug = models.SlugField(unique=True)
    description = models.TextField()
    content = models.TextField()
    date_posted = models.DateTimeField(default=timezone.now)
    author = models.ForeignKey(User, on_delete=models.CASCADE)

    def __str__(self):
        return self.title

    def save(self, *args, **kwargs):
        if not self.slug:
            self.slug = unique_slug_generator(self)
        return super().save(*args, **kwargs)

我正在尝试的信号

from django.db.models.signals import pre_save
from .utils import unique_slug_generator
from django.dispatch import receiver
from .models import Post


@receiver(pre_save, sender=Post)
def pre_save_post_receiver(sender, instance, *args, **kwargs):
    print("post reciver slug")
    if not instance.slug:
        instance.slug = unique_slug_generator(instance)

还有我尝试运行的独特的段塞发生器

from django.utils.text import slugify
import random
import string


def random_string_generator(size=10, chars=string.ascii_lowercase + string.digits):
    return ''.join(random.choice(chars) for _ in range(size))


def unique_slug_generator(instance, new_slug=None):
    """
    This is for a Django project and it assumes your instance
    has a model with a slug field and a title character (char) field.
    """
    if new_slug is not None:
        slug = new_slug
    else:
        slug = slugify(instance.title)

    Klass = instance.__class__
    qs_exists = Klass.objects.filter(slug=slug).exists()
    if qs_exists:
        new_slug = "{slug}-{randstr}".format(
                    slug=slug,
                    randstr=random_string_generator(size=4)
                )
        return unique_slug_generator(instance, new_slug=new_slug)
    return slug

谢谢你抽出时间