与mongo db不同的值？

Question

I want to get unique values from mongo db. I have tried a lot but could not found the correct solution. this is how i am fetching values from mongo db.

    Mongo mongo = new Mongo("localhost", 27017);
    DB db = mongo.getDB("test");

    DBCollection collection = db.getCollection("testCollection");


    String hopKey = UUID.randomUUID().toString();           

    System.out.println("BasicDBObject example...");
    BasicDBObject document = new BasicDBObject();
    document.put("host", "http://localhost:5050");
    document.put("key", hopKey);
    document.put("appName", "BANK2");
    document.put("userId", "xym@gmail.com");         
    //collection.insert(document);

    List cursorDoc = collection.distinct("appName");
    System.out.println(cursorDoc.get(0).toString());

This is giving me the list size as 2 which is correct. but how can i get all the row values for these 2 unique values. Because i need to use all values of these two unique in jsp file. Please help me.

Answer 1

collection.distinct('appName')

will give you all the different values in your collection that exist for that particular fieldName. If you know that all documents have some kind of value there, then you can just do

collection.find({})

If you are not sure that the field exists for each document, then you only want to documents where that field exists

collection.find({'appName' : {'$exists' :true}})

That will get you all the documents that have the field 'appName' defined and the value will be one of the two values that you are expecting from your collection.distinct('appName') command