Django频道

Question

I've little question about Django Channels, WebSockets, and chat applications. Serving with google gets me to chatrooms, where people can connect and start a chat. But I don't know how one user can send another user instant message.

For example:

1) I add John to friends, and want to start chat. 2) On server side I can generate object Room, with me and John as members. 3) When I send message via WebSocket to this room, I know for who this message is, but I don't know how to get John's channel

@channel_session_user_from_http
def ws_connect(message):
    rooms_with_user = Room.objects.filter(members=message.user)
    for r in rooms_with_user:
        Group('%s' % r.name).add(message.reply_channel)

@channel_session_user
def ws_receive(message):
    prefix, label = message['path'].strip('/').split('/')

    try:
        room = Room.objects.get(name=label)
    except Exception, e:
        room = Room.objects.create(name=get_random_string(30))
        for u in message.chmembers:
            room.members.add(u)
            # here can be somethis like this
            # try
            reply_channel = Channels.objects.get(online=True, user=u)
            Group('%s' % r.name).add(reply_channel)
    Group('%s' % room.name).send({
        "text": "%s : %s" % (message.user.username, message['text']),
    })

@channel_session_user
def ws_disconnect(message):
    prefix, label = message['path'].strip('/').split('/')
    Group(label).discard(message.reply_channel)

Answer 1

Simply make "automatic unique rooms" for user pairs. The rest stays the same. For example like this

def get_group_name(user1, user2):
    return 'chat-{}-{}'.format(*sorted([user1.id, user2.id]))

Give it two user objects, and it returns a unique room for that pair of users, ordered the User.id , something like "chat-1-2" for the users with User.id "1" and "2".

That way, a user can connect with more than one logged-in device and still get the messages sent between the two users.

You can get the authenticated user's object from message.user .

For the receiving User object, I'd just sent the username along with the message. Then you can unpack it from the message['text'] the same way you unpack the actual message.

payload = json.loads(message.content['text'])
msg = payload['msg']
sender = message.user
receiver = get_object_or_404(User, username=payload['receiver'])
# ... here you could check if they have required permission ...
group_name = get_group_name(sender, receiver)
response = {'msg': msg}
Group(group_name).send({'text': json.dumps(response)})
# ... here you could persist the message in a database ...

So with that, you can drop all the "room" things from your example, including the room table etc. Because group names are always created on-the-fly when a message is send between two users.

---

Another important thing: One user will connect later than the other user, and may miss initial messages. So when you connect, you probably want to check some "chat_messages" database table, fetch the last 10 or 20 messages between the user pair, and send those back. So users can catch up on their past conversation.