Save and display comment in real-time using angularjs and socket.io - angularjs

Question

I have problem with socket.io. In my code router.post(/comment,...) saving user comments in database (using mongoose) and I am trying emit this save. In controller function readMoreCourse is to get and display all comments from database (and question how use socket to this function that using ng-reapat display comment in real-time). Function AddComment is on client side chceck valid form and next post comment to database.
My question: How in real-time save and display user comment using angular (ng-repeat?) and socket.io? Honestly I making this first time, and I have short time, thanks for any help.
Server
io.on('connection', function(socket){
socket.emit('comment', function(){
console.log('Comment emitted')
})
socket.on('disconnect', function(){
})
})
API
router.post('/comment', function(req, res) {
Product.findOne({ _id: req.body._id }, function(err, product){
if(err) {
res.json({ success:false, message: 'Course not found' })
} else {
User.findOne({ username: req.decoded.username }, function(err, user){
if(err){
res.json({ success:false, message: 'Error'})
} else {
product.comments.push({
body: req.body.comment,
author: user.username,
date: new Date(),
});
product.save(function(err){
if(err) throw err
res.json({ success: true, message: 'Comment added })
**io.emit('comment', msg);**
})
}
})
}
})
})
controller
Socket.connect();
User.readMoreCourse($routeParams.id).then(function(data){
if(data.data.success){
app.comments = data.data.product.comments;
} else {
$window.location.assign('/404');
}
});
app.AddComment = function(comment, valid) {
if(valid){
var userComment = {};
userComment.comment = app.comment;
Socket.on('comment', User.postComment(userComment).then(function(data){
if(data.data.success){
$timeout(function(){
$scope.seeMore.comment = '';
},2000)
} else {
app.errorMsg = data.data.message;
}
}));
} else {
app.errorMsg = 'Error';
}
}
$scope.$on('$locationChangeStart', function(event){
Socket.disconnect(true);
})
factory
userFactory.readMoreCourse = function(id) {
return $http.get('/api/seeMore/' + id)
}
userFactory.postComment = function(comment){
return $http.post('/api/comment', comment);
}
.factory('Socket', function(socketFactory){
return socketFactory()
})

Answer 1

In your socket factory, initialize socket.io emit and on events.
app.factory('socket', ['$rootScope', function($rootScope) {
var socket = io.connect();
return {
on: function(eventName, callback){
socket.on(eventName, callback);
},
emit: function(eventName, data) {
socket.emit(eventName, data);
}
};
}]);
and call this from controller
app.controller('yourController', function($scope, socket) {
User.postComment(userComment).then(function(data){
if(data.data.success){
$timeout(function(){
$scope.seeMore.comment = '';
},2000);
// Emit new comment to socket.io server
socket.emit("new comment", userComment);
} else {
app.errorMsg = data.data.message;
}
});
// other clients will listen to new events here
socket.on('newComment', function(data) {
console.log(data);
// push the data.comments to your $scope.comments
});
from socket.io server
io.on('connection', function(socket) {
// listen for new comments from controller and emit it to other clients
socket.on('new comment', function(data) {
io.emit('newComment', {
comment: data
});
});
});
EDIT:
If you just want to push from server side,
io.on('connection', function(socket) {
// after saving your comment to database emit it to all clients
io.emit('newComment', {
comment: data
});
});
and remove this emit code from controller:
socket.emit("new comment", userComment);
But this method can be tricky because the user who posts the comment should immediately see the comment added to the post. If you let socket.io to handle this there will be a few seconds lag for the guy who posted the comment.