text: from django.db import models
  
  from store.models import Product
  
  
  class Cart(models.Model):
      cart_id = models.CharField(max_length=255, blank=True)
      date = models.DateField(auto_now_add=True)
  
      def __str__(self):
          return self.cart_id
  
  
  class CartItem(models.Model):
      product = models.ForeignKey(Product, on_delete=models.CASCADE)
      cart = models.ForeignKey(Cart, on_delete=models.CASCADE)
      quantity = models.IntegerField()
      is_active = models.BooleanField(default=True)
  
      def sub_total(self):
          return self.product.price * self.quantity
  
      def __str__(self):
          return self.product
  