通过 Java 向 Mongo 集合中的每个文档添加新字段

Question

如何向现有集合中的每个文档添加新字段？

这是我目前尝试过的方法

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);

Answer 1

你应该使用多更新：

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