Jongo vs (DBObject)JSON.parse

Question

I'm trying to figure out the advantage of Jongo over simply unmarshalling the json command using (DBObject)JSON.parse(...) and using the DBObject in the below fashion.

Is there a performance advantage?

    @Override
public List<T> getEntityList(Integer limit, String query) throws Exception {
    log.entering(DaoImpl.class.toString(), "getEntityList, with criteria of " + query);
    DBObject criteriaObject = null;
    ArrayList<T> list = new ArrayList<T>();

    if (query != null)
        criteriaObject = (DBObject)JSON.parse(query);

    DBCursor cursor = null;

    try {
        if (criteriaObject != null) {
            log.log(Level.FINEST, "getting the objects using a search criteria: " + criteriaObject);
            cursor = MongoDB.getInstance().getCollection(collection).find(criteriaObject);
        } else {
            log.log(Level.FINEST, "getting the objects without a criteria");
            cursor = MongoDB.getInstance().getCollection(collection).find();
        }

        ............etc, etc, etc

Thanks!

score 2 · Answer 1 · answered Jan 19 '13 at 14:47

2

Jongo .3 unmarshalls Mongo query with the same JSON.parse(query). The advantage is the way you get the results from the database. In your example, you have to iterate through a cursor, adapting every property and sub property by yourself.

DBObject dbo = JSON.parse("{age: 18}");
DBCursor results = users.find(dbo);
for (DBObject result : results) {
    User user = new User();
    user.setUsername((String) result.get("username"));
    user.setAge((Integer) result.get("age"));
    user.setAddress(new Address(..));
}

With Jongo you directly manipulate objects:

Iterable<User> users = collection.find("{age: 18}").as(User.class);

Jongo's performance is nearly equal to the driver's.

answered Jan 19 '13 at 14:47

yves amsellem

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I use gson to unmarshall the response, so I don't need to set every property myself. And Jongo also iterates through each result and unmarshalls it using JSON. So that's not an issue: new DomainConverter(clazz).getObject(entity.toString()) – Vladimir Jan 19 '13 at 15:51
You used GSON to unmarshall the DBCursor response? Can you please show a complete example of code? The Jongo team have been working hard to make that unmarshalling step as performant as the driver; have you computed the performance of your solution? – yves amsellem Jan 20 '13 at 10:32
I'm not unmarshalling the cursor, rather the DBObject(s) returned by the cursor. – Vladimir Jan 22 '13 at 07:42

score 1 · Answer 2 · edited Feb 16 '13 at 09:10

1

Here is a list of few advantages to use jongo:

Almost all queries can be templated :

friends.find("{name:#, age:#}", "Joe", 18)

Binded parameters can be BSON Primitives or any complex type :
```
friends.find("{address: #}", new Address(..)); 
```
Querying and unmarshalling is as fast as the driver. No Jackson process extra cost
Use Jackson features to map you Pojo: polymorphism, JsonView...

BTW your GSON un/marshaller can be integrated into Jongo by implementing a Mapper.

edited Feb 16 '13 at 09:10

assylias

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answered Jan 21 '13 at 15:55

Benoît Guérout

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Templating does simplify some things, but I still don't see this being a good-enough reason to switch to jongo -- this can easily be achieved with string-replace. One way or another, if nobody else provides a better answer I'll accept yours. – Vladimir Jan 22 '13 at 20:51

Jongo vs (DBObject)JSON.parse

2 Answers2