Add new field to every document in Mongo Collection through Java

Question

How can I add a new field to every document in an existent collection?

This is what I have tried so far

MongoClient mongo = new MongoClient("localhost", 27017);
DB db = mongo.getDB("myDB");
DBCollection collection = db.getCollection("myCollection");
DBObject test = new BasicDBObject();
DBObject add = new BasicDBObject();
add.put("xxx", "newField");
collection.update(add, test);

HPCS · Accepted Answer · 2019-07-03 05:59:31Z

1

You should use update multi:

    DBObject queryAll = new BasicDBObject();
    DBObject newValue = new BasicDBObject("xxx", "newField");
    DBObject update = new BasicDBObject("$set", newValue);
    collection.updateMulti(queryAll, update);

answered Jul 3, 2019 at 5:59

HPCS

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6 Comments

G.Brown Over a year ago

Used your code, but new field is not getting appended to all jsons

HPCS Over a year ago

is it append to some of the documents? or not at all?

G.Brown Over a year ago

Code seems correct, but it's not at all appending the field to json

HPCS Over a year ago

Does collection.find() returns any documents?

G.Brown Over a year ago

If I use for loop in this context, everything will be overridden by last value. You think is there a way to update them one by one?

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