Aggregation using MongoDB java driver

Question

I'm using MongoDB java driver 3.2.2 to do some aggregation operations, but I'm not sure if something could be achieved through it.

The original query in MongoDB is:

db.getCollection('report').aggregate({
$group: {
    _id: "$company_id",
    count: {
            $sum: {
                    $cond: [{
                            $eq: ["$idcard.status", "normal"]
                        },0,1]
                }
            }
    }
})

I have no idea of how to put the "$cond" as a parameter of "$sum" operator in Java driver in the code section below:

        AggregateIterable<Document> res = col.aggregate(Arrays.asList(
            group("$company_id",
                    sum("count", ...)
            )));

I've searched the official document about this with no result, anyone has experience of doing this? Thanks.

s7vr · Accepted Answer · 2016-11-21 13:46:43Z

1

For 3.x drivers

Using BsonDocument : Type Safe Version

BsonArray cond = new BsonArray();
BsonArray eq = new BsonArray();
eq.add(new BsonString("$idcard.status"));
eq.add(new BsonString("normal"));
cond.add(new BsonDocument("$eq", eq));
cond.add(new BsonInt64(0));
cond.add(new BsonInt64(1));

AggregateIterable<BsonDocument> aggregate = dbCollection.aggregate(Arrays.asList(
        group("$company_id",
                sum("count", new BsonDocument("$cond", cond))
    )));

Using Document - Less Code but Not Type Safe

List cond = new ArrayList();
cond.add(new Document("$eq", Arrays.asList("$idcard.status", "normal")));
cond.add(0);
cond.add(1);

AggregateIterable<Document> aggregate = dbCollection.aggregate(Arrays.asList(
        group("$company_id",
                sum("count", new Document("$cond", cond))
        )));

edited Nov 21, 2016 at 13:46

answered Nov 21, 2016 at 13:06

s7vr

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1 Comment

jinreal Over a year ago

Finally I use the Document class for this case, thanks for the precise explanation of the difference!

Community · Accepted Answer · 2017-05-23 11:45:58Z

0

To use $cond in Java use ArrayList.

{ $cond: [ { $eq: ["$idcard.status", "normal"] },0,1]

// To Acheive this - [ "$idcard.status", "normal" ]

ArrayList eqArrayList = new ArrayList();
eqArrayList.add("$idcard.status");
eqArrayList.add("normal");

// To Acheive this - [ { $eq: [ "$idcard.status", "normal" ] } , 1, 0 ]

 ArrayList condArray = new ArrayList();
 condArray.add(new BasicDBObject("$eq", eqArrayList));
 condArray.add(1);
 condArray.add(0);

// Finally - { $cond: [ { $eq: ["$idcard.status", "normal" ] } , 1, 0 ] }

BasicDBObject fullCond = new BasicDBObject("$cond", condArray);

Also see: MongoDB aggregation condition translated to JAVA driver

edited May 23, 2017 at 11:45

CommunityBot

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answered Nov 21, 2016 at 13:02

Clement Amarnath

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1 Comment

s7vr Over a year ago

BasicDBObject is for 2.x driver version. BsonDocument and Document is recommended for 3.x driver version.

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