socket.io并从mongodb获取数据

Question

I'm coding a simple messaging app and I have most of it working. I'm currently trying to retrieve the old messages that saved into my database and have it show up in my app.

server.js

io.sockets.on('connection', function(socket) {
   Chat.find({}, function(err, docs) {
      if(err) throw err;
      console.log('sending previous messages');
      socket.emit("load old messages", docs);
   });

    socket.on('new user', function(data, callback){
        if (data in users){
            callback(false);
        } else{
            callback(true);
            socket.nickname = data;
            users[socket.nickname] = socket;
            updateNicknames();
        }
    });

messaging.html just the javascript

<script>
    jQuery(function($){
        var socket = io.connect();
        var $nickForm = $('#setNick');
        var $nickError = $('#nickError');
        var $nickBox = $('#nickname');
        var $users = $('#users');
        var $messageForm = $('#send-message');
        var $messageBox = $('#message');
        var $chat = $('#chat');

        $nickForm.submit(function(e){
            e.preventDefault();
            socket.emit('new user', $nickBox.val(), function(data){
                if(data){
                    $('#nickWrap').hide();
                    $('#contentWrap').show();
                } else{
                    $nickError.html('That username is already taken!  Try again.');
                }
            });
            $nickBox.val('');
        });

        socket.on('usernames', function(data){
            var html = '';
            for(var i=0; i < data.length; i++){
                html += data[i] + '<br/>'
            }
            $users.html(html);
        });

        $messageForm.submit(function(e){
            e.preventDefault();
            socket.emit('send message', $messageBox.val(), function(data){
                $chat.append('<span class="error">' + data + "</span><br/>");
            });
            $messageBox.val('');
        });

        socket.on('load old msgs', function(docs) {
            for (var i=0; i < docs.length; i++) {
                displayMsg(docs[i]);
            }
        });

        socket.on('new message', function(data){
            displayMsg(data);

        });

        function displayMsg (data) {
            $chat.append('<span class="msg"><b>' + data.nick + ': </b>' + data.msg + "</span><br/>");
        }

        socket.on('whisper', function(data){
            $chat.append('<span class="whisper"><b>' + data.nick + ': </b>' + data.msg + "</span><br/>");
        });
    });
</script>

This line of code is supposed to retrieve from the server and display the old message but it is not working:

socket.on('load old msgs', function(docs) {
            for (var i=0; i < docs.length; i++) {
                displayMsg(docs[i]);
            }
        });

This is the part of the code that gave me trouble as I'm getting the API which is called Chat and trying to send to my user side. However, in my console log from the server side code, it does saying sending old messages so I'm guessing it working correctly even though not sure. This has been giving me trouble for so long and I need help.

Answer 1

I think you have a mismatch on events here:

socket.emit("load old messages", docs);

socket.on('load old msgs', function(docs) {
            for (var i=0; i < docs.length; i++) {
                displayMsg(docs[i]);
            }
});

It should be:

socket.on('load old messages', function(docs) {
            for (var i=0; i < docs.length; i++) {
                displayMsg(docs[i]);
            }
});