how to get a value of sub collection in array in mongodb using java

Question

How to print the value of filename??

>db.register.find().pretty()
{
     "name":"abc",
     "files":[
                {
                       "filename":"web.html",
                       "content_type":"text/html"
                },
                {
                       "filename":"import.doc",
                       "content_type":"text/doc"
                }
            ]
}

the java code i used is:

            String a = request.getParameter("Name");
            MongoClient mongo = new MongoClient("localhost", 27017);
            DB db = mongo.getDB("smart");
            DBCollection coll = db.getCollection("register");
            DBCursor doc = coll.find(new BasicDBObject("name", a));

     while(doc.hasNext())
                {
            BasicDBObject dbObject = (BasicDBObject)doc.next();    
            String fname = dbObject.getString("files.filename");
                    out.println(fname);
                }

But im unable to get the field value... plzz help me to fix this.

thanx in advance

Answer 1

files is an array of embedded documents. So, you can get BasicDBList first, then iterate on it's fields and find value corresponding to filename :-

    while (doc.hasNext()) {
        BasicDBObject dbObject = (BasicDBObject) doc.next();
        BasicDBList list = (BasicDBList) dbObject.get("files");
        for(Object obj : list ){
            String fname = ((BasicDBObject)obj).getString("filename");
            System.out.println(fname);
        }
     }