Django

Question

我正在尝试在 post 上制作一个按钮，当用户点击它时，请求将其作为出席添加到 post，然后 post 必须批准该请求。

Models.py

class Attending(models.Model):
    is_approved = models.BooleanField(default=False)
    attending = models.ManyToManyField(User, related_name='user_event_attending')

class Post(models.Model):
    title = models.CharField(max_length=100)
    content = models.TextField(blank=True)
    date_posted = models.DateTimeField(default=timezone.now)
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    attending = models.ForeignKey(Attending, on_delete=models.CASCADE, verbose_name='atending', null=True)

我的问题是，每次我为按钮编写查询时都会出现错误，我无法弄清楚如何获取外键的反向。

这是我在 views.py

上的代码

def request_event(request, pk):
    previous = request.META.get('HTTP_REFERER')
    try:
        query = Attending.objects.get(pk=pk)
        request_attending = query.post_set.add(request.user)
        messages.success(request, f'Request sent!')
        return redirect(previous)
    except query.DoesNotExist:
        return redirect('/')

非常感谢您的提前帮助！

Answer 1

这：query.post_set只是关系。你不能像那样调用方法 add 。您可以添加到 ManyToMany 关系，我相信您想将用户添加到 Attending.attending 字段，而不是直接添加到 Post 对象。将其更改为：

...
query = Attending.objects.get(pk=pk)
query.attending.add(request.user)
messages.success(request, f'Request sent!')
....

|更新 |

我认为你应该考虑重新安排你的人际关系。如果我理解你的计划，你应该这样做：

class Attending(models.Model):
    ...
    attendant = models.ForeignKey(User, related_name='events_attending', on_delete=models.CASCADE)
    post = models.ForeignKey('Post', on_delete=models.CASCADE)

class Post(models.Model):
    ...
    author = models.ForeignKey(User, on_delete=models.CASCADE)

一个Post对象可以有多个Attending对象，那么你可以使用这样的关系：

att = Attending.objects.first()
att.post                         # get related Post object from ForeignKey | there is only one

post = Post.objects.first()
post.attending_set.all()         # get all related Attending objects

Post.objects.get(attending=att)  # get Post object that the Attending object have in ForeignKey field

user = User.objects.first()
user.post_set.all()              # get all Post objects that User is author in
user.events_attending.all()      # get all related Attending objects

更多检查Django Docs。

Django - 在视图中通过外键查询

Django - Query by foreign key in views

python

foreign-keys