如何格式化mongodb查找查询的结果？

Question

我有一个以这种格式存储数据的集合:

{
    _id: ObjectId("51b9be6dbbdeef1e5f008cca"),
    name: 'sfdsfsdfsdfsdfsd'
    details: {
        varA: {
            created: "2013-06-13T12:43:25.853Z",
            validity: "2013-07-13T12:43:25.853Z",
            modified: "2013-06-13T12:43:25.853Z"
        },
        varB: {
            created: "2013-06-13T12:43:25.853Z",
            validity: "2013-07-13T12:43:25.853Z",
            modified: "2013-06-13T12:43:25.853Z"
        }
    }
}

我希望能够只显示这种格式的varA数据(没有嵌套的深度...):

{ 
    _id: ObjectId("51b9be6dbbdeef1e5f008cca"),
    name: 'sfdsfsdfsdfsdfsd',
    created: "2013-06-13T12:43:25.853Z",
    validity: "2013-07-13T12:43:25.853Z",
    modified: "2013-06-13T12:43:25.853Z"
}

不幸的是,我的查询(我使用投影):

db.coll.find({}, {'details.varB': 0})

返回这样的东西:

{
    _id: ObjectId("51b9be6dbbdeef1e5f008cca"),
    name: 'sfdsfsdfsdfsdfsd',
    details: {
        varA: {
            created: "2013-06-13T12:43:25.853Z",
            validity: "2013-07-13T12:43:25.853Z",
            modified: "2013-06-13T12:43:25.853Z"
        }
}

如何改进查找查询以返回预期的格式？

非常感谢那些能帮助我的人;-)

PS这里我使用mongo shell来检索数据,但我需要使用node-mongodb-native的node.js进行此查询.

Answer 1

我只用聚合函数完成了这个,正如我在这里的博客文章中所解释的那样

对于您的情况,这是有效的

db.temp.aggregate (
   {
      $project : 
      {
         name:"$name",
         created:"$details.varA.created",
         validity:"$details.varA.validity",
         modified:"$details.varA.modified"
      }
   }
);

要么

db.temp.aggregate ({$project:{name:"$name",created:"$details.varA.created",validity:"$details.varA.validity",modified:"$details.varA.modified"}});

这是样本运行

> db.temp.insert ({name:'sfdsfsdfsdfsdfsd', details: { varA : { created: "2013-06-13T12:43:25.853Z", validity: "2013-07-13T12:43:25.853Z", modified: "2013-06-13T12:43:25.853Z"}, varB : { created: "2013-06-13T12:43:25.853Z", validity: "2013-07-13T12:43:25.853Z", modified: "2013-06-13T12:43:25.853Z" } } })
> db.temp.aggregate ({$project:{name:"$name",created:"$details.varA.created",validity:"$details.varA.validity",modified:"$details.varA.modified"}});
{
        "result" : [
                {
                        "_id" : ObjectId("51b9d7151723a9c4d6bc9936"),
                        "name" : "sfdsfsdfsdfsdfsd",
                        "created" : "2013-06-13T12:43:25.853Z",
                        "validity" : "2013-07-13T12:43:25.853Z",
                        "modified" : "2013-06-13T12:43:25.853Z"
                }
        ],
        "ok" : 1
}