Django model 中设置联合约束和联合索引

 
class Cart(models.Model):
    user = models.ForeignKey(
        MyUser,
        verbose_name="用户"
    )
    goods = models.ForeignKey(
        Goods,
        verbose_name="商品"
    )
    num = models.IntegerField(
        verbose_name="商品数量"
    )
    is_select = models.BooleanField(
        default=True,
        verbose_name="选中状态"
    )
 
    class Meta:
        # 联合约束   其中goods和user不能重复
        unique_together = ["goods", "user"]
        # 联合索引， 其中"goods"和"user"联合同步查询，提高效率
        index_together = ["user", "goods"]