java - 使用java在mongodb中进行多次更新

Question

我有这个文档:

{
        "_id" : ObjectId("54140782b6d2ca6018585093"),
        "user_id" : ObjectId("53f4ae1ae750619418a20467"),
        "date" : ISODate("2014-09-13T08:59:46.709Z"),
        "type" : 0,
        "tot" : 2,
        "additional_info" : {
                "item_id" : ObjectId("540986159ef9ebafd3dcb5d0"),
                "shop_id" : ObjectId("53f4cc5a6e09f788a103d0a4"),
                "ap_id" : ObjectId("53f4cc5a6e09f788a103d0a5")
        },
        "transactions" : [
                {
                        "_id" : ObjectId("54140782b6d2ca6018585091"),
                        "date_creation" : ISODate("2014-09-13T08:59:46.711Z"),
                        "type" : -1
                },
                {
                        "_id" : ObjectId("54140782b6d2ca6018585092"),
                        "date_creation" : ISODate("2014-09-13T08:59:46.788Z"),
                        "type" : 1
                }
        ]
}

我需要向第一个事务对象添加另外 2 个字段:- 执行日期:日期- 结果:这个bson文档

{ "server_used" : "xxx.xxx.xxx.xxx:27017" , "ok" : 1 , "n" : 1 , "updated_executed" : true} (m_OR.getDocument() in the following code example)

获取该文档

    {
        "_id" : ObjectId("54140811b6d25137753c1a1a"),
        "user_id" : ObjectId("53f4ae1ae750619418a20467"),
        "date" : ISODate("2014-09-13T09:02:09.098Z"),
        "type" : 0,
        "tot" : 2,
        "additional_info" : {
                "item_id" : ObjectId("540986159ef9ebafd3dcb5d0"),
                "shop_id" : ObjectId("53f4cc5a6e09f788a103d0a4"),
                "ap_id" : ObjectId("53f4cc5a6e09f788a103d0a5")
        },
        "transactions" : [
                {
                        "_id" : ObjectId("54140811b6d25137753c1a18"),
                        "date_creation" : ISODate("2014-09-13T09:02:09.100Z"),
                        "type" : -1,
                        "result" : {
                                "server_used" : "xxx.xxx.xxx.xxx:27017",
                                "ok" : 1,
                                "n" : 1,
                                "updated_executed" : true
                        },
                        "date_execution" : ISODate("2014-09-13T09:02:15.370Z")
                },
                {
                        "_id" : ObjectId("54140811b6d25137753c1a19"),
                        "date_creation" : ISODate("2014-09-13T09:02:09.179Z"),
                        "type" : 1
                }
        ]
}

我能够做到这一点的唯一方法是执行 2 个单独的更新(更新是我的包装函数，它在 mongodb 中执行真正的更新并且工作正常):

    // where
    BasicDBObject query = new BasicDBObject();
    query.append("transactions._id", m_Task.ID());

    // new value for result - 1st upd
    BasicDBObject value = new BasicDBObject();
    value.put("$set",new BasicDBObject("transactions.$.date_execution",new Date()));
    update(this._systemDB, "activities", query, value);

    // new value for date_execution - 2nd upd
    value = new BasicDBObject();
    value.put("$set",new BasicDBObject("transactions.$.result",m_OR.getDocument()));
    update(this._systemDB, "activities", query, value);

如果我尝试这样做:

    BasicDBObject value = new BasicDBObject();
    value.put("$set",new BasicDBObject("transactions.$.date_execution",new Date()));
    value.put("$set",new BasicDBObject("transactions.$.result",m_OR.getDocument()));
    or = update(this._systemDB, "activities", query, value);

仅应用第二组。

有没有办法避免双重执行并只需一次调用即可应用更新？

Answer 1

“哈希/映射”对象的基本规则是只能有一个键。这是普遍适用的“高地人”规则(“只能有一个”)。因此，只需以不同的方式应用即可:

BasicDBObject value = new BasicDBObject();
value.put("$set",
    new BasicDBObject("transactions.$.date_execution",new Date())
        .add( new BasicDBObject("transactions.$.result",m_OR.getDocument() )
);

所以基本上“两个”字段参数都是“$set”语句的一部分，如序列化形式所示:

{
   "$set": {
       "transactions.$.date_execution": new Date(),
       "transactions.$.result": m_Or.getDocument()
   }
}

这基本上就是你最终想要的。