Question

I’m using nodejs, mongoose odm, and mongo for a web app and am running into issues trying to run “group by” style query in mongoose:

var results = mymodel.collection.group (
{   
    keyf:
        function(doc)
        {
                var m = doc.date.getMonth();
                var d = doc.date.getDate();
                var y = doc.date.getFullYear();
                return { date: m + "/" + d + "/" + y };
        },
    cond: {},
    reduce: function(doc,prev) { prev.total += doc.value; },
    initial: { total: 0 }
}
);
if(results == null)
{
    console.log("results is null\n");
}

if I run the “mymodel.collection.group” code in mongo shell, it works perfectly. However, in nodejs/mongoose it seems to return a null result even though the mongoose documentation states that direct mongo code could be executed against the native mongo driver.

does anyone have any ideas how to resolve?

Answer 1

I have just managed to do it in Mongoose. To do it you need to create a chained call and in the callback do the reduce.

var foo = function(name, callback){
 Model.where('user', name).
        select('points').
        run(callback);
}

So the above is the map and then reduce is

foo(name, function(errors, docs){ 
                var score = 0; 
                for (var i=0; i < docs.length; i++){ 
                  score += docs[i].points;
                });

That works for my needs at the moment