Question

我有一种行之有效的方法,但似乎很奇怪,我认为这样做有更好的办法。

我有一份模型,把我的网站上的用户(用于学习目的的tw带)与其他用户名单联系起来。

现在,在我创建新用户的时候,我希望把这份名单与用户一起作为名单的成员。

我的模式是:

class FollowerList(models.Model)
    follower = models.ForeignKey(User,related_name="follower")
    followed = models.ManyToManyField(User,related_name="followed")

我认为,现在使用的是Im。

user = User.objects.get(username=uname)
flst = FollowerList()
flst.follower = user
flst.save()
flst.followed.add(user)
flst.save()

在我看来,should 是创造这种机会的一种方法,而无需打上save(<>/code>两次,但我似乎无法在docs或其他任何地方找到。

Answer 1

你们不需要在很多2many.add()之后打电话。

您还可以将守则缩短为2行:

flst = FollowerList.objects.create(follower=user)
flst.followed.add(user)

Answer 2

Yuji的答复是正确的。在M2M油田被拯救之前,你不能再添加物体。我想提一下的是,通过这种方式来制造一些例子。

user = User.objects.get(username=uname)
flst = FollowerList(follower=user) #use key word args to assign fields
flst.save()
flst.followed.add(user)
# don t need to save after adding an object to many to many field.

我发现,除制造空洞和分配田地外, s子稍有nic。尽管物体(Yuki语)方法(Yuki语)仍然nic。

Answer 3

A 对这一的延迟答复:您也可超越构件(_init__):

class FollowerList(models.Model):
    follower = models.ForeignKey(User,related_name="follower")
    followed = models.ManyToManyField(User,related_name="followed"

    def __init__(*args, followed=[], **kwargs):
        super(FollowerList, self).__init__(*args, **kwargs)
        self.save()
        for user in followed:
            self.followed.add(user)

ie here I ve explicitly handled the followed keyword argument in the __init__ function, while passing all other args and kwargs on to the default constructor. The call to save makes sure that the object has been registered and can thus be used in an m2m relationship.

This then allows you to do create FollowerList with one line, eg

flst = FollowerList(follower=user, followed=[user,])

Alternatively, as pointed out by Johannes, saving a model in the __init__ is not expected. The preferred approach would be to create a Manager method - see here for details: https://docs.djangoproject.com/en/1.9/topics/db/managers/ and then to create a FollowerList:

fl = FollowerList.objects.create(*args, followed, **kwargs)

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