Aggregation and Find Operator in MongoDB?

Question

I have an use case where I have find all the matching records and apply the aggregation like count, sum, group by etc .
Can I use such scenarios where I have to use find and aggregate function together or should I find then get the cursor object and have to perform aggregation operation separately

Answer 1

Here is the script example you can edit it and use in as per your requirement,
MongoDB Script:

db.collectionname.group({
    "key": {
        "UserName": true
    },
    "initial": {
        "sumscore": 0,
        "sumforaverageaveragescore": 0,
        "countforaverageaveragescore": 0,
        "countstar": 0
    },
    "reduce": function(obj, prev) {
        prev.sumscore = prev.sumscore + obj.score - 0;
        prev.sumforaverageaveragescore += obj.score;
        prev.countforaverageaveragescore++;
        prev.minimumvaluescore = isNaN(prev.minimumvaluescore) ? obj.score : Math.min(prev.minimumvaluescore, obj.score);
        prev.maximumvaluescore = isNaN(prev.maximumvaluescore) ? obj.score : Math.max(prev.maximumvaluescore, obj.score);
        if (true != null) if (true instanceof Array) prev.countstar += true.length;
        else prev.countstar++;
    },
    "finalize": function(prev) {
        prev.averagescore = prev.sumforaverageaveragescore / prev.countforaverageaveragescore;
        delete prev.sumforaverageaveragescore;
        delete prev.countforaverageaveragescore;
    },
    "cond": {
        "score": {
            "$gt": 0
        },
        "UserName": {
            "$in": ["shivam", "anonymous"]
        }
    }
});

its SQL script is:

SELECT UserName, SUM(score), AVG(score), MIN(score), MAX(score), COUNT(*) 
FROM collectionname
WHERE score > 0 AND UserName IN('shivam','anonymous') 
GROUP BY UserName;

Let me know if it fulfills your requirement.Thanks.