Meteor/Fibers - How to use Meteor.call callback? - serialization

Question

I have this code, where I call a Meteor method from the client and expect a result in the callback. the results object is a well formed object that I can stringify and print from the server's console.
When I run this code, with a valid results and no error, the callback is not called on the client. However, if I substitute fut.return(results) with fut.return(JSON.parse(JSON.stringify(results))), the callback is called and I get "a string" in the client. Any idea why I can return a string but no object?
Server code (in Meteor.Methods()):
getUserEvents : function(userId,start,end) {
var fut = new Future();
getUserEventsPrivate(userId,start,end,function(err,results){
if(err){
fut.throw(new Meteor.Error( 500, 'Oops, something wrong happened'));
}else{
fut.return(results); // works when fut.return(JSON.parse(JSON.stringify(results)));
}
});
return fut.wait();
}
Client:
Meteor.call('getUserEvents',Meteor.user()._id, startStr, endStr,function(err,results){
console.log(results);
});
EDIT
here is the Json I'm trying to pass as 'results':
[
{
"title": "ResponsiveMTL #1",
"start": "2015-10-13T21:30:00.000Z",
"end": "2015-10-14T00:30:00.000Z"
},
{
"title": "Meteor Global Distributed Hackathon",
"start": "2015-10-10T15:00:00.000Z",
"end": "2015-10-11T15:00:00.000Z"
},
{
"title": "retenues a la source",
"start": "2015-10-08T19:25:00.275Z",
"end": "2015-10-08T19:25:00.275Z"
},
{
"title": "Salsa",
"start": "2015-09-19T22:00:00.000Z",
"end": "2015-09-19T23:00:00.000Z"
},
{
"title": "Salsa",
"start": "2015-10-09T22:00:00.000Z",
"end": "2015-10-09T23:00:00.000Z"
}
]

Answer 1

It is entirely possible to return an object this way.
Your object is probably not EJSON-serializable out of the box, although it is hard to tell without actually looking at a sample of it.
If, for example, your objects contain circular references, EJSON will silently fail and your callback won't be called. It is unlikely that this is the case, as you are able to get JSON to serialize it.
You can try to find the offending properties and modify them, but it might be a good idea to register it as a custom type with EJSON.
http://docs.meteor.com/#/full/ejson_add_type
Anyway, it would be interesting to see your actual objects and be able to tell more.
What version of Meteor are you using?