What is the correct way to do a HAVING in a MongoDB GROUP BY?

For what would be this query in SQL (to find duplicates):

SELECT userId, name FROM col GROUP BY userId, name HAVING COUNT(*)>1

I performed this simple query in MongoDB:

res = db.col.group({key:{userId:true,name:true}, 
                     reduce: function(obj,prev) {prev.count++;}, 
                     initial: {count:0}})

I've added a simple Javascript loop to go over the result set, and performed a filter to find all the fields with a count > 1 there, like so:

for (i in res) {if (res[i].count>1) printjson(res[i])};

Is there a better way to do this other than using javascript code in the client? If this is the best/simplest way, say that it is, and this question will help someone :)

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What is the correct way to do a HAVING in a MongoDB GROUP BY?

1 Answer

New answer using Mongo aggregation framework

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