在mongodb 3.2x中不使用$ facet单独展开2个阵列

Question

目标：我需要根据日期和时间提取帖子和分享并排序，然后将它们放在一个对象数组中

{
    "_id": {
        "$oid": "5919e1f8b1f75c2b1cb504ea"
    },
    "user": {
        "$oid": "58deb7db5aac7a0011d7bdf4"
    },
    "likes": [],
    "comments": [],
    "posts": [
        {
            "p_Id": {
                "$oid": "596b16b1c657d21d8048287d"
            },
            "Date": {
                "$date": "2017-07-16T07:33:06.238Z"
            }
        },
        {
            "p_Id": {
                "$oid": "596b3068183c4f24d853f228"
            },
            "Date": {
                "$date": "2017-07-16T09:22:49.451Z"
            }
        }
    ],
    "__v": 331,
    "shares": [
        {
            "sh_Id": {
                "$oid": "596b2d65d65e092778a41e31"
            },
            "Date": {
                "$date": "2017-07-16T09:09:57.666Z"
            }
        },
        {
            "sh_Id": {
                "$oid": "596b2d9e371b5c2194775c0d"
            },
            "Date": {
                "$date": "2017-07-16T09:10:54.701Z"
            }
        }
    ]
}

期望的结果：

       [ {
            "p_Id": {
                "$oid": "596b16b1c657d21d8048287d"
            },
            "Date": {
                "$date": "2017-07-16T07:33:06.238Z"
            }
        },
        {
            "sh_Id": {
                "$oid": "596b2d65d65e092778a41e31"
            },
            "Date": {
                "$date": "2017-07-16T09:09:57.666Z"
            }
        },
        {
            "sh_Id": {
                "$oid": "596b2d9e371b5c2194775c0d"
            },
            "Date": {
                "$date": "2017-07-16T09:10:54.701Z"
            }
        },
        {
            "p_Id": {
                "$oid": "596b3068183c4f24d853f228"
            },
            "Date": {
                "$date": "2017-07-16T09:22:49.451Z"
            }
        },
        {
            "p_Id": {
                "$oid": "596b3071183c4f24d853f229"
            },
            "Date": {
                "$date": "2017-07-16T09:22:57.911Z"
            }
        }]

我的查询：

    Activity.aggregate([
         { $match : { user : mongoose.Types.ObjectId(data.user) } },
         { $unwind: "$posts" }, { $unwind: "$shares"},
         { $project : { _id: 0, posts: 1, shares: 1 } }
         ]).exec(function(err,result){
                console.log(result);
         });

但是这个查询会成对出现结果。即在子文档中，每个共享发生相同的帖子。例如

我的结果：

[ { posts:
     { p_Id: 596b16b1c657d21d8048287d,
       Date: 2017-07-16T07:33:06.214Z },
    shares:
     { sh_Id: 596b2d65d65e092778a41e31,
       Date: 2017-07-16T09:09:57.666Z } },
  { posts:
     { p_Id: 596b16b1c657d21d8048287d,
       Date: 2017-07-16T07:33:06.214Z },
    shares:
     { sh_Id: 596b2d9e371b5c2194775c0d,
       Date: 2017-07-16T09:10:54.701Z } },
  { posts:
     { p_Id: 596b16b1c657d21d8048287d,
       Date: 2017-07-16T07:33:06.214Z },
    shares:
     { sh_Id: 596b30c1183c4f24d853f22c,
       Date: 2017-07-16T09:24:17.621Z } }]