mongodb command with sort and limit

Question

Hi i am trying to implement this exact command below using the Mongo Java api

db.system.profile.find({},{millis:1}).sort({$natural:-1}).limit(1);

I was thinking of doing something like below, but i am only expecting a single INT to be returned and this may be a wrong/long way of doing it.

Mongo mongoClient = new Mongo( "localhost" , 27017 );
        DB db = mongoClient.getDB( "user" );    
        /*  db.system.profile.find({},{millis:1}).sort({$natural:-1}).limit(1);*/
        DBCollection collTime = db.getCollection("system.profile");
        DBCursor cursor = collTime.find(new BasicDBObject("millis", 1),new BasicDBObject("$natural", -1)).limit(1);  
        System.out.println(cursor.toString());

Any help would be great!

nutlike · Accepted Answer · 2013-02-20 22:26:31Z

4

Have a look at public DBObject findOne(DBObject o, DBObject fields, DBObject orderBy). Code would look something like this:

String str = collection.findOne(new BasicDBObject(), new BasicDBObject("millis", 1),
    new BasicDBObject("$natural", -1)).get("millis").toString();

edited Feb 20, 2013 at 22:26

answered Feb 20, 2013 at 21:22

nutlike

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4 Comments

edited Over a year ago

Im getting (Cursor id=0, ns=user.system.profile, query={ "millis" : 1}, fields={ "$natural" : -1}, numIterated=0, limit=1, addr=localhost:27017, readPreference=ReadPreference.PRIMARY) any ideas? thanks!

nutlike Over a year ago

Should your edit represent your current code? Then please read carefully my given answer: The function to call is findOne(…) instead of find(…), the return value is a DBObject instead of a DBCursor and the first parameter should be an empty DBObject since it represents the query. Please copy and paste my code and try again.

edited Over a year ago

Yes the update does represent my current code. I don't have access to that specific method for some reason so i was trying another way. Ill try find out why i don't have it. Thanks!

nutlike Over a year ago

The method is available since version 2.9.0 - any chance to upgrade? Otherwise I think you have to go with your first approach.

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