Example usage for com.mongodb DBCollection group

Introduction

In this page you can find the example usage for com.mongodb DBCollection group.

Prototype

@Deprecated
public DBObject group(final DBObject key, final DBObject cond, final DBObject initial, final String reduce) 

Source Link

Document

Group documents in a collection by the specified key and performs simple aggregation functions such as computing counts and sums.

Usage

From source file:mongodb.javaGroup.java

public static void firstIsALastIsVowel(DBCollection collection) {
    BasicDBObject key = new BasicDBObject("first", true);
    key.append("last", true);
    BasicDBObject cond = new BasicDBObject("first", "a");
    cond.append("last", new BasicDBObject("$in", new String[] { "a", "e", "i", "o", "u" }));
    BasicDBObject initial = new BasicDBObject("count", 0);
    String reduce = "function (obj, prev) { prev.count++; }";
    DBObject result = collection.group(key, cond, initial, reduce);
    System.out.println("\n'A' words grouped by first and last" + " letter that end with a vowel");
    javaGroup.displayGroup(result);/*from w  ww. j  a va2  s .c o m*/
}

---

From source file:net.cit.tetrad.rrd.dao.MongoStatusToMonitorImpl.java

License:Open Source License

public List<Object> readMongoChunksGrp(Mongo mongo, String collName, List<Object> dboLst)
        throws MongoException, Exception {
    try {/*from   w w  w.  j  av a  2  s.c om*/
        DB db = mongo.getDB("config");
        DBCollection dbcollection = db.getCollectionFromString("chunks");
        DBObject dbo = dbcollection.group(new BasicDBObject("shard", true), new BasicDBObject("ns", collName),
                new BasicDBObject("nChunks", 0), "function (doc, out) {out.nChunks++;}");
        Iterator<String> keys = dbo.keySet().iterator();
        BasicDBObject getDbo;
        while (keys.hasNext()) {
            String key = keys.next();
            getDbo = (BasicDBObject) dbo.get(key);
            getDbo.put("collName", collName);
            dboLst.add(getDbo);
        }
    } catch (DataAccessResourceFailureException e) {
        e.printStackTrace();
        throw new MongoException(e.getMessage());
    } catch (MongoException e) {
        e.printStackTrace();
        throw e;
    } catch (Exception e) {
        e.printStackTrace();
        throw e;
    } finally {

    }
    return dboLst;
}

---