May I ask how is this going？

[lvlinux]

from django.db import models

# Create your models here.

class Topic(models.Model):
    """用户学习的主题"""
    text = models.CharField(max_length=200)
    date_added = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.text

Error:
Traceback (most recent call last):
  File "C:/Python/study_notes/agss/models.py", line 5, in <module>
    class T(models.Model):
  File "C:\Python\study_notes\11_env\lib\site-packages\django\db\models\base.py", line 100, in __new__
    app_config = apps.get_containing_app_config(module)
  File "C:\Python\study_notes\11_env\lib\site-packages\django\apps\registry.py", line 244, in get_containing_app_config
    self.check_apps_ready()
  File "C:\Python\study_notes\11_env\lib\site-packages\django\apps\registry.py", line 127, in check_apps_ready
    raise AppRegistryNotReady("Apps aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.