Django模型錯誤：可以使用此多對多關係之前的字段x

Question

嘗試從用戶添加多對多關係時出現以下錯誤。

ValueError: "" needs to have a value for field "appuser" before this many-to-many relationship can be used.

這裏是我的東西，做...

> user = AppUser(email="test@test.com", password="password") 
> address = Address(name="test",address_line1="1") 
> user.address.add(address) 

用戶模型：

class AppUser(AbstractBaseUser): 
    email = models.EmailField(
     verbose_name='email address', 
     max_length=254, 
     unique=True, 
     db_index=True, 
    ) 
    address = models.ManyToManyField('users.Address', null=True, blank=True) 

地址型號：

class Address(Base): 
    name = models.CharField(max_length=255) 
    address_line1 = models.CharField('Address Line 1', max_length=100) 
    def __unicode__(self): 
     return self.name 

Answer 1

您需要保存的對象然後創建它們之間的多對多關係。

user = AppUser(email="test@test.com", password="password") 
address = Address(name="test",address_line1="1") 
user.save() 
address.save() 
user.address.add(address) 

原因是，每多到多的關係字段存儲在保存兩個對象的ID的一個單獨的表及其數據。對象之間的關係是該表中的行。所以很明顯，對象首先需要有ID才能輸入關係。他們通過保存獲得ID。