如何在 Django 中获取带有用户 ID 的 ManyToManyField 对象？

Question

I have a little built-in Chat with Django Channels and I created a Chat model where I can store the messages (it is like a CHAT ROOM with ID) and I want to get the single object by the 2 users ID.

I tried something like Chat.objects.filter(participiants__in=[ID1,ID2]) but it just returns every single chat they are in.

def post(self,request):

        sender = UserProfile.objects.get(user_id=request.user.id)

        message = request.data.get('message')
        post_id = request.data.get('post_id')
        recipient_id = request.data.get('recipient_id')

        chat_room = Chat.objects.filter(participiants__in=[sender, recipient_id])

class Chat(models.Model):
    participiants = models.ManyToManyField(UserProfile, related_name="chats")
    messages = models.ManyToManyField(Message, blank=True, related_name="messages")

    def get_room_messages(self):
        messages = self.messages.order_by('-timestamp').all()
        return [[i.text,i.sender_id,i.link,i.post_id] for i in messages]

Answer 1

You should then count the number of participants after filtering, and check if that is equal to 2 , like:

from django.db.models import 

chat_rooms = Chat.objects.filter(
    participiants__in=[sender, recipient_id]
).annotate(
    
).filter()

If there is exactly one such Chat object, you can use .get(..) instead:

from django.db.models import Count

chat_rooms = Chat.objects.filter(
    participiants__in=[sender, recipient_id]
).annotate(
    nparticipants=Count('participiants')
)nparticipants=2