django - 如何查询多对多字段中仅描述的对象存在的位置

Question

我如何检查是否有 thread仅包含 sender (用户 1)和 recipient (用户 2)，没有其他用户。

模型.py

class Thread(models.Model):
    user = models.ManyToManyField(User)
    is_hidden = models.ManyToManyField(User, related_name='hidden_thread', blank=True)

class Message(models.Model):
    thread = models.ForeignKey(Thread)
    sent_date = models.DateTimeField(default=datetime.now)
    sender = models.ForeignKey(User)
    body = models.TextField()
    is_hidden = models.ManyToManyField(User, related_name='hidden_message', blank=True)

我试过

>>> Thread.objects.filter(user=user1&user2)
>>> Thread.objects.filter(user=user1|user2)
# Both gave me an error:  Unsupported operand.

# Then this
>>> Thread.objects.filter(Q(user=user1) & Q(user=user2))
# Which gave me no threads at all.

# Then this
>>> Thread.objects.filter(Q(user=user1) | Q(user=user2)).distinct()
# Gave me threads of both the users.

我想要的是仅与指定用户一起检查线程。假设，用户1想给用户2发送一条消息，我想要的是，首先检查两个用户之间是否存在线程。如果有，请获取该线程，否则创建一个新线程。这怎么可能？最好的方法是什么。请帮我。谢谢你。

请告诉我 | 和有什么区别和 & ?因为我对这两者的结果非常不同。

编辑:

>>> t1 = Thread.objects.get(id=1)
>>> t1
[<User: a>,<User: b>]
>>> t2 = Thread.objects.get(id=2)
>>> t2
[<User: a>,<User: b>,<User: c>]
>>> t3 = Thread.objects.get(id=3)
>>> t3
[<User:a>,<User: c>]
>>> t4 = Thread.objects.get(id=4)
>>> t4
[<User:a>,<User:b>]

我想要的是让线程只有用户 a和用户 b存在，并且没有其他用户。在这种情况下，它将是: t1和 t4 .希望我说清楚了。谢谢你。

Answer 1

excludedUsers = Users.objects.exclude(id__in=[user1.id, user2.id])
Thread.objects.filter(users=user1).filter(users=user2).exclude(users__in=excludedUsers)