如何在用户模型的外键字段中使用on_delete属性设置用户全名? [英] How can I set user full name in foreignkey field with User Model using on_delete attribute?
问题描述
我在django中有一个带有用户模型的外键的模型。
I have a model in django that have foreignkey with User model.
class News(models.Model):
user = models.ForeignKey(AUTH_USER_MODEL, on_delete=models.SET(???))
message - models.TextField()
所以当任何用户帐户从数据库中删除时,在新闻表项中也会根据用户删除。所以我想要当任何用户帐户被删除时,我需要使用'on_delete = models.SET(???)'
So When any user account delete from database then in News table entries also deleted according to user. So I want that When any user account deleted then I need to set his/her full name in user field using 'on_delete=models.SET(???)'
示例:
Example:
如果我有用户first_name ='Neeraj'和last_name ='Kumar'
当我想删除该用户帐户,然后在新闻表中,我想保存他的名字。
If I have user that first_name = 'Neeraj' and last_name='Kumar' When I want to delete that user account then in News table I want to save his name.
推荐答案
用户
字段新闻
模型映射到用户
模型实例。
user
field in News
Model maps to a User
Model instance.
您无法为此字段分配字符串。您只能分配null a User
model instance。
You cannot assign a string to this field. You can only assign either null a User
model instance.
您必须提供替代用户来代替已删除的用户。所以要么在删除时保留替换用户或创建一个用户。在 docs 。
You will have to provide a substitute user to put in place of the deleted user. So either reserve a user for substitution or create one at the time of deletion. It is explained very clearly in the docs.
您可以做的一件事是向<$ c $中添加一个新的名称
c>新闻模型,并在创建新闻
实例时填充。
One thing you can do is to add a new name
field to the News
model and populate it when creating the News
instance.
class News(models.Mode):
user = models.ForeignKey(AUTH_USER_MODEL, on_delete=models.SET_NULL)
name = models.CharField()
def save(self, *args, **kwargs):
if not self.id:
self.name = self.user.first_name + self.user.last_name
super(News, self).save(*args, **kwargs)
现在,当用户
被删除时,用户
字段设置为NULL, code> name 字段包含所需的名称信息。
Now when User
is deleted, user
field is set to NULL and name
field contains the required name information.
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