(MongoDB Java) $push into array

Question

我使用mongo 2.2.3和java驱动程序。我的困境，我不得不$推一个字段和值到一个数组，但我似乎不能弄清楚如何做到这一点。我的数据样本:

"_id" : 1,
"scores" : [
    {
        "type" : "homework",
        "score" : 78.97979
    },
    {
        "type" : "homework",
        "score" : 6.99
    },
    {
        "type" : "quiz",
        "score" : 99
    }
]

我可以在shell中$push:

db.collection.update({_id:1},{$push:{scores:{type:"quiz", score:99}}})

但是当我把它翻译成java时，我把自己弄糊涂了，把键盘扔到墙上。

我的Java代码(不完整和错误):

DBObject find = new BasicDBObject("_id", 1);
DBObject push = new BasicDBObject("$push", new BasicDBObject(
                        "scores", new BasicDBObject()));

Answer 1

DBObject listItem = new BasicDBObject("scores", new BasicDBObject("type","quiz").append("score",99));
DBObject updateQuery = new BasicDBObject("$push", listItem);
myCol.update(findQuery, updateQuery);

Answer 2

由于mongodb-driver 3.1.有一个构建器类com.mongodb.client.model.Updates，它为每个更新情况提供了适当的方法。在这种情况下，这将是:

Document score = new Document().append("type", "quiz")
                               .append("score",99);
collection.updateOne(eq("_id", "1"),Updates.addToSet("scores", score));

Answer 3

如果您对shell的查询格式更熟悉，您可能会发现使用JSON.parse为$push构造DBObject更容易:

import com.mongodb.util.JSON;
String json = "{$push:{scores:{type:'quiz', score:99}}}";
DBObject push = (DBObject) JSON.parse(json);

Answer 4

使用Jongo，您可以在shell中这样做:

db.collection.update({_id:1},{$push:{scores:{type:"quiz", score:99}}})

变成Java:

collection.update("{_id:1}").with("{$push:{scores:{type:#, score:#}}}", "quiz", 99);

不需要花哨的DBObject;-)

Answer 5

MongoDB Java驱动程序可以简化此操作。使用$each代替$push。

$each mongodb reference document

Java示例-

    BasicDBObject addressSpec = new BasicDBObject();
    addressSpec.put("id", new ObjectId().toString());
    addressSpec.put("name", "one");
    BasicDBObject addressSpec2 = new BasicDBObject();
    addressSpec2.put("id", new ObjectId().toString());
    addressSpec2.put("name", "two");
    List<BasicDBObject> list = new ArrayList<>();
    list.add(addressSpec); list.add(addressSpec2);
    UpdateResult updateOne = individualCollection.updateOne(Filters.eq("_id", "5b7c6b612612242a6d34ebb6"), 
            Updates.pushEach("subCategories", list));