如何根据flask-socketio中的房间选择显示聊天记录

Question

i have some issues here: I'm currently working on a chat application using flask-socketio, everything is actually working fine but i want to add the functionality of allowing users that recently join a room to see the previous chats that were there before they joined, with respect to the room they selected. I'm really stock on figuring out the logic of the functionality. Below is what i did. The issue is how do i loop through the chats that is being sent to the front-end, or is there a better way of doing it?

@socketio.on('join')
def join(data):
    join_room(data['room'])

    room_name = data['room']

    chats = engine.execute(text(
        """SELECT * FROM chat_history WHERE room = :room_name"""), ({"room_name": room_name},)).fetchall()

    if chats:

        send({'msg': data['username'] + " has joined the " + data['room'] + " room."}, room=data['room'], chats=chats)

Answer 1

You need to separate the new user announcement from the chat history, since the announcement goes to everybody in the room, but the chat history only to the user joining.

You could continue to announce the user with send, but then use emit() with a dedicated event for users joining, where you can include the chat history as an argument:

# announce the new user as before
send({'msg': data['username'] + " has joined the " + data['room'] + " room."}, room=data['room'])

# pass chat history to the new user (note there is no room argument on this one)
emit('joined', chats)

Then in the client you add a handler for the joined event and there you render your chat history.

I hope this makes sense!