How to retrieve a value from mongoDB?

Question

I am new to mongoDB and using java with mongoDB. I have a json where I want to retrieve the column names and not the value.I also need to store it in two different array.

Desired output is:

column [ ] = views, AddToCart, AddToWishList, ZoomedProductImage

list [ ] = fSymbol, num, operator

and the JSON:

{
    "views": {
        "fSymbol": "",
        "num": 0.1,
        "operator": "*"
    },
    "AddToCart": {
        "fSymbol": "+",
        "num": 0.15,
        "operator": "*"
   },
   "AddToWishList": {
       "fSymbol": "+", 
       "num": 0.1,
       "operator": "*"
   },
   "ZoomedProductImage": {
       "fSymbol": "+",
       "num": 0.07,
       "operator": "*"
   }   
}

Please visit this link hope this will help you . http://stackoverflow.com/questions/2298870/mongodb-get-names-of-all-keys-in-collection — praveen_programmer, May 14 '15 at 10:56
@praveen_programmer thanks man..but i need to do it through java. — Ritesh Sinha, May 14 '15 at 10:59

singhakash · Accepted Answer · 2015-05-14T11:14:37.020

3

Try keySet() method.

BasicDBObject searchQuery = new BasicDBObject();
DBCursor cursor = table.find(searchQuery);

while (cursor.hasNext()) {
    System.out.println(cursor.next().keySet());
}

check the docs

edited May 14 '15 at 11:14

answered May 14 '15 at 11:03

singhakash

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Also,I need to store it in a string array. – Ritesh Sinha May 14 '15 at 11:26
Gives this error: Exception in thread "main" java.lang.ClassCastException: java.util.HashMap$KeySet cannot be cast to com.mongodb.BasicDBObject – Ritesh Sinha May 14 '15 at 11:36
**while (cursor2.hasNext()) { BasicDBObject a=(BasicDBObject)cursor2.next().keySet(); }** – Ritesh Sinha May 14 '15 at 11:36
ok my bad try `Set a=cursor.next().keySet();` method `keySet()` return `Set` – singhakash May 14 '15 at 11:41

score 1 · Answer 2 · answered May 14 '15 at 11:01

1

Since BasicDBObject extends HashMap, you have just to get the keyset from it.

answered May 14 '15 at 11:01

Enrichman

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How to retrieve a value from mongoDB?

2 Answers2