如何限制对象在django-taggit中可以拥有的最大标记数？

pip install django-taggit

INSTALLED_APPS = [
    # ...
    'taggit',
    # ...
]

from django.db import models
from taggit.managers import TaggableManager

class MyModel(models.Model):
    tags = TaggableManager(blank=True, help_text='A comma-separated list of tags.')
    # ...

from django.db import models
from taggit.managers import TaggableManager

class MyModel(models.Model):
    tags = TaggableManager(blank=True, help_text='A comma-separated list of tags.')
    # ...

    def save(self, *args, **kwargs):
        if len(self.tags.all()) > 5:
            raise ValueError("最多只能添加 5 个标签。")
        super().save(*args, **kwargs)