How do I limit the number of results when using the Java driver for mongo db?

Question

http://api.mongodb.org/java/2.1/com/mongodb/DBCollection.html#find(com.mongodb.DBObject,com.mongodb.DBObject,int,int)

Using this with Grails and the mongo db plugin.

Here's the code I'm using... not sure why but the cursor is returning the entire set of data. In this case, I'm just trying to return the first 20 matches (with is_processed = false):

def limit = {
    def count = 1;
    def shape_cursor = mongo.shapes.find(new BasicDBObject("is_processed", false),new BasicDBObject(),0,20);
    while(shape_cursor.hasNext()){
        shape_cursor.next();
        render "<div>" + count + "</div"
        count++;
    }
}

Anyone have an idea?

Answer 1

limit is a method of DBCursor: DBCursor.limit(n).

So you simply need to do

def shape_cursor = mongo.shapes.find(...).limit(20);