在 Django 模型中引用多个字段

Question

我正在尝试从特定的 Django 模型中引用 2 个字段，但它一直给我错误。模型如下所示，我想从属性表到客户表引用“building_type”和“location”

class Property(models.Model):
    location = models.CharField(choices=Property_Location, max_length=120)
    building_type= models.CharField(choices=Property_Type, max_length=120)
    initial_quantity= models.IntegerField(null= False, blank= False)
    quantity_in_stock= models.IntegerField( null= False, blank= False) 
    quantity_sold = models.IntegerField( null= False, blank= False) 

    def __str__(self):
        return self.location



class Client(models.Model):
    first_name = models.CharField(max_length=120)
    last_name = models.CharField(max_length=120)
    phone = models.IntegerField()
    email = models.EmailField(max_length=130)
    building_type= models.ForeignKey(Property,null= False, blank= False,  
    on_delete=models.CASCADE) 
    location= models.ForeignKey(Property, null= False, blank= False, on_delete=models.CASCADE)

    def __str__(self):
       return self.first_name + ' '+ self.last_name