I'm trying to interrogate if any of the clients in a room have a particular property associated with them. The async nature of the socket.io get method is causing me problems. I've seen the async library, which looks like it might be what I need, but I'm having difficulties visualising how to apply that to this situation.
Here is how I'd like the function to work, assuming the get wasn't async;
/**
*
**/
socket.on('disconnect', function(data) {
socket.get('room', function(err, room) {
if(!roomHasProperty(room)) {
io.sockets.in(room).emit('status', { message: 'property-disconnect' });
}
});
});
/**
*
**/
var roomClients = function(room) {
var _clients = io.sockets.clients(room);
return _clients;
}
/**
*
**/
var roomHasProperty = function(room) {
// get a list of clients in the room
var _clients = roomClients(room);
// build up an array of tasks to be completed
var tasks = [];
// loop through each socket in the room
for(key in _clients) {
var _socket = _clients[key];
// grab the type from the sockets data store and check for a control type
_socket.get('type', function (err, type) {
// ah crap, you already went ahead without me!?
if(type == 'property') {
// found a the property type we were looking for
return true;
}
});
}
// didn't find a control type
return false;
}
Is there a better way of doing this?
Have you considered using a promises library? It makes dealing with async functions a lot easier. If you were to use Q, you could do this: (I'm sorry, i can't check the code right now, but I'm pretty sure it should work almost with no changes)
var roomHasProperty = function(room) {
// Create the deferred object
var deferred = Q.defer();
// get a list of clients in the room
var _clients = roomClients(room);
// array of promises to check
var promises = [];
// This function will be used to ask each client for the property
var checkClientProperty = function (client) {
var deferred = Q.defer();
// grab the type from the sockets data store and check for a control type
client.get('type', function (err, type) {
// ah crap, you already went ahead without me!?
if(type == 'property') {
// found a the property type we were looking for
deferred.resolve(true);
} else {
// property wasn't found
deferred.resolve(false);
}
});
return deferred.promise;
}
// loop through each socket in the room
for(key in _clients) {
promises.push(checkClientProperty(_clients[key]));
}
Q.all(promises).then(function (results) {
deferred.resolve(results.indexOf(true) > -1);
})
// didn't find a control type
return deferred.promise;
}
You can use this like this:
checkClientProperty(client).then(function (result) {
if (result) {
console.dir('the property was found');
} else {
console.dir('the property was not found');
}
});