我的應(yīng)用程序中有各種模型。但是，有一個我無法注冊，所以我可以在admin panel.所以在我的cart應(yīng)用程序admin.py文件中，我可以使用：from django.contrib import adminfrom .models import Cart, CartItem# Register your models here.admin.site.register(Cart)但不是：from django.contrib import adminfrom .models import Cart, CartItem# Register your models here.admin.site.register(Cart, CartItem)因?yàn)槲沂盏酱隋e誤： File "/home/ogonzales/Escritorio/projects_envs/perfectcushion_env/lib/python3.6/site-packages/django/contrib/admin/checks.py", line 26, in check_admin_app    errors.extend(site.check(app_configs))  File "/home/ogonzales/Escritorio/projects_envs/perfectcushion_env/lib/python3.6/site-packages/django/contrib/admin/sites.py", line 81, in check    if modeladmin.model._meta.app_config in app_configs:AttributeError: 'CartItem' object has no attribute 'model'購物車/models.py：from django.db import modelsfrom shop.models import Product# Create your models here.class Cart(models.Model):    cart_id = models.CharField(max_length=250, blank=True)    date_added = models.DateField(auto_now_add=True)    class Meta:        db_table = 'Cart'        ordering = ['date_added']    def __str__(self):        return self.cart_idclass CartItem(models.Model):    product = models.ForeignKey(Product, on_delete=models.CASCADE)    cart = models.ForeignKey(Cart, on_delete=models.CASCADE)    quantity = models.IntegerField()    active = models.BooleanField(default=True)    class Meta:        db_table = 'CartItem'    def sub_total(self):        return self.product.price * self.quantity    def __str__(self):        return self.product