Mongodb查找和获取输出平面树结构？

Question

我在这里有两个收集点集合和用户集合我想基于用户ID进行聚合。

在这里，我正在尝试聚合，一切正常，但我需要修改结果

db.points.aggregate([ 
     $match: {
      store: "001",
      date: {$lte: ISODate("2017-11-10T08:15:39.736Z"), $gte: ISODate("2017-11-10T08:15:39.736Z")}
    },

    {
    $lookup: {
      from: "users",
      localField: "userid",
      foreignField: "_id",
      as: "user"
    }
  },

   {

       $project: 

       {


       _id:0,
       "userdata.purchasedetails.purchaseid" : 1,
       "userdata.purchasedetails.data" : 1,
       usermobinumber: { "$arrayElemAt": [ "$user.mobinumber", 0 ] }



    }}  

数据存储方式如下

{
    "userpoint": "2",
    "date":ISODate("2017-11-10T08:15:39.736Z"),
    "store":"001",
    "userid":[
    objectID("5a7565ug8945rt67"),
    objectID("8a35553d3446rt78")
    ],
    "userdata":{
        "profile":[],
        "purchasedetails":
        [{
                "purchaseid":"dj04944",
                "data":"awe"

        }]
    }
}

得到这样的结果：

{
"usermobinumber":"9611",
"userdata":{
        "purchasedetails":
        [{
                "purchaseid":"dj04944",
                "data":"awe"

        }]
}

我期待的结果：

我不希望树结构输出我需要这样

{
 "usermobinumber":"9611",
 "purchaseid":"dj04944",
 "data":"awe"
 }

我该怎么做才能帮助我

Answer 1

你可以在这里做这样的事情，

db.points.aggregate([
    //Whatever you are doing here now (lookup and match)
    {
        $project:{
            "usermobinumber":"$usermobinumber",
            "purchaseid":"$userdata.purchasedetails.purchaseid"
        }
    }
])

这会给你：

{
    "usermobinumber" : "9611",
    "purchaseid" : [ 
        "dj04944"
  ]
}

编辑：

db.points.aggregate([
        //Whatever you are doing here now (lookup and match)
        {
            {
             $project:{
                 "usermobinumber":"$usermobinumber",
                 "purchaseid":"$userdata.purchasedetails.purchaseid",
                 "data":"$userdata.purchasedetails.data"
               }
            }
        }
    ])

这会给你

{
 "usermobinumber":"9611",
 "purchaseid":["dj04944"],
 "data":["awe"]
 }

purchaseid和data是数组，因为purchasedetails是一个数组。

Answer 2

您可以添加$ unwind阶段来展平结果....