Node.js 如何在mongoose中查找最近的子文档

我有一个名为

RegisterList

的mongoose文档，该文档包含名为

Booking

的子文档

这里我需要检索子文档，它是最近添加的子文档

下面是我的json数据

[
    {
        _id: "56a3174bfc518cd014af7abd",
        area_name: "padi",
        name: "Vignesh",
        email: "vignesh4008@gmail.com",
        mobile_no: "9282438685",
        otp: "1625",
        __v: 0,
        date: "2016-01-23T06:01:47.450Z",
        booking: [
            {
                name: "Vignesh",
                mobile: "9282438685",
                can_name: "Kinley",
                can_quantity: "2",
                can_cost: "80",
                can_path: "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png",
                delivery_date: "23-01-2016",
                delivery_timeslot: "3pm-8pm",
                order_id: "S16064",
                subscription: "true",
                subscription_type: "EveryDay",
                total_cost: "560",
                address: "12,Ramanrajan street,,padi,Chennai",
                _id: "56a3174bfc518cd014af7abe",
                delivered_at: "2016-01-22T18:30:00.000Z",
                ordered_at: "2016-01-23T06:01:47.451Z",
                status: "Delivered"
            },
            {
                name: "Vignesh",
                mobile: "9282438685",
                can_name: "Kinley",
                can_quantity: "2",
                can_cost: "80",
                can_path: "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png",
                delivery_date: "24-01-2016",
                delivery_timeslot: "3pm-8pm",
                address: "12,Ramanrajan street,,padi,Chennai",
                order_id: "S16064",
                subscription_type: "EveryDay",
                _id: "56a31ba2d55894ec15eac1cf",
                ordered_at: "2016-01-23T06:20:18.479Z",
                status: "UnderProcess"
            }
        ]
    },
    {
        _id: "56a0bc8d3306f388131e56c6",
        area_name: "kodambakkam",
        name: "Ganesh",
        email: "ganesh@gmail.com",
        mobile_no: "9042391491",
        otp: "7828",
        __v: 0,
        date: "2016-01-21T11:10:05.074Z",
        booking: [
            {
                name: "Ganesh",
                mobile: "9042391491",
                can_name: "Bisleri",
                can_quantity: "5",
                can_cost: "250",
                can_path: "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png",
                delivery_date: "23-01-2016",
                delivery_timeslot: "3pm-8pm",
                order_id: "S12348",
                subscription: "true",
                subscription_type: "Alternate",
                total_cost: "1000",
                address: "15/A,Main Street,kodambakkam,Chennai",
                _id: "56a3164dc2c549e811c0d08f",
                delivered_at: "2016-01-22T18:30:00.000Z",
                ordered_at: "2016-01-23T05:57:33.169Z",
                status: "Delivered"
            },
            {
                name: "Ganesh",
                mobile: "9042391491",
                can_name: "Bisleri",
                can_quantity: "5",
                can_cost: "250",
                can_path: "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png",
                delivery_date: "25-01-2016",
                delivery_timeslot: "3pm-8pm",
                address: "15/A,Main Street,kodambakkam,Chennai",
                order_id: "S12348",
                subscription_type: "Alternate",
                _id: "56a31c29d55894ec15eac1d0",
                ordered_at: "2016-01-23T06:22:33.307Z",
                status: "UnderProcess"
            }
        ]
    }
]

如何单独查找最近插入的子文档。在给定的JsonCode中

我们将非常感谢您的帮助

更新：

---

我需要为

和
交货日期
和
状态
查找
和
条件的数据，因此如何编写mongoose查询以获取数据
基于假设，您可以使用聚合框架获取最新的子文档

Mongodb版本3.2+

MongoDB版本<3.2

根据您提供的示例文档，输出如下所示

{ 
    "_id" : "56a3174bfc518cd014af7abd", 
    "booking" : {
        "name" : "Vignesh", 
        "mobile" : "9282438685", 
        "can_name" : "Kinley", 
        "can_quantity" : "2", 
        "can_cost" : "80", 
        "can_path" : "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png", 
        "delivery_date" : "24-01-2016", 
        "delivery_timeslot" : "3pm-8pm", 
        "address" : "12,Ramanrajan street,,padi,Chennai", 
        "order_id" : "S16064", 
        "subscription_type" : "EveryDay", 
        "_id" : "56a31ba2d55894ec15eac1cf", 
        "ordered_at" : "2016-01-23T06:20:18.479Z", 
        "status" : "UnderProcess"
    }, 
    "area_name" : "padi", 
    "name" : "Vignesh", 
    "email" : "vignesh4008@gmail.com", 
    "mobile_no" : "9282438685", 
    "date" : "2016-01-23T06:01:47.450Z"
}
{ 
    "_id" : "56a0bc8d3306f388131e56c6", 
    "booking" : {
        "name" : "Ganesh", 
        "mobile" : "9042391491", 
        "can_name" : "Bisleri", 
        "can_quantity" : "5", 
        "can_cost" : "250", 
        "can_path" : "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png", 
        "delivery_date" : "25-01-2016", 
        "delivery_timeslot" : "3pm-8pm", 
        "address" : "15/A,Main Street,kodambakkam,Chennai", 
        "order_id" : "S12348", 
        "subscription_type" : "Alternate", 
        "_id" : "56a31c29d55894ec15eac1d0", 
        "ordered_at" : "2016-01-23T06:22:33.307Z", 
        "status" : "UnderProcess"
    }, 
    "area_name" : "kodambakkam", 
    "name" : "Ganesh", 
    "email" : "ganesh@gmail.com", 
    "mobile_no" : "9042391491", 
    "date" : "2016-01-21T11:10:05.074Z"
}

不完全清楚你在问什么。您是指集合中每个文档的数组中最新的“

”排序值吗？或者您可能是指集合中“所有”文档中具有最新值的子文档？无论如何，在任何给定文档中，“最后一个”数组项始终是最新的，除非您特别在位置添加新项或在更新时对数组进行排序。您确切地说是指最新的“排序的”吗集合中每个文档的数组中的值如果通过

$push

操作符将子文档推送到

booking

数组中，它会将元素插入数组的末尾。除非在其中。因此，我们希望得到的使操作简单的澄清是，如果“最近的”总是在数组的末尾（默认情况下，没有其他修改），那么您真正需要的是从每个文档返回的数组的“最后”元素。当然，这里有一个内置的“投影”操作符，我也确信之前这里已经有人问过直接问题。您想在处订购最新的

，可能是的副本吗？
db.col.aggregate([
    // Stage 1
    {
      $unwind: "$booking"
    },

    // Stage 2
    {
      $sort: {
      "booking.ordered_at":-1
      }
    },

    // Stage 3
    {
      $group: {
      _id: {
        id: "$_id",
        "area_name" : "$area_name", 
        "name" : "$name", 
        "email" : "$email", 
        "mobile_no" :"$mobile_no", 
        "otp" : "$opt", 
        "date" : "$date"   
        },
        booking:{$first: "$booking"}
      }
    },

    // Stage 4
    {
      $project: {
        _id: 0,
        _id: "$_id.id",
        "area_name" : "$_id.area_name", 
        "name" : "$_id.name", 
        "email" : "$_id.email", 
        "mobile_no" :"$_id.mobile_no", 
        "otp" : "$_id.opt", 
        "date" : "$_id.date",
        "booking": 1
      }
    }
  ]);

{ 
    "_id" : "56a3174bfc518cd014af7abd", 
    "booking" : {
        "name" : "Vignesh", 
        "mobile" : "9282438685", 
        "can_name" : "Kinley", 
        "can_quantity" : "2", 
        "can_cost" : "80", 
        "can_path" : "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png", 
        "delivery_date" : "24-01-2016", 
        "delivery_timeslot" : "3pm-8pm", 
        "address" : "12,Ramanrajan street,,padi,Chennai", 
        "order_id" : "S16064", 
        "subscription_type" : "EveryDay", 
        "_id" : "56a31ba2d55894ec15eac1cf", 
        "ordered_at" : "2016-01-23T06:20:18.479Z", 
        "status" : "UnderProcess"
    }, 
    "area_name" : "padi", 
    "name" : "Vignesh", 
    "email" : "vignesh4008@gmail.com", 
    "mobile_no" : "9282438685", 
    "date" : "2016-01-23T06:01:47.450Z"
}
{ 
    "_id" : "56a0bc8d3306f388131e56c6", 
    "booking" : {
        "name" : "Ganesh", 
        "mobile" : "9042391491", 
        "can_name" : "Bisleri", 
        "can_quantity" : "5", 
        "can_cost" : "250", 
        "can_path" : "http://test15.watervan.in/wp-content/uploads/2015/07/p-95-WV-Kinley-25l.png", 
        "delivery_date" : "25-01-2016", 
        "delivery_timeslot" : "3pm-8pm", 
        "address" : "15/A,Main Street,kodambakkam,Chennai", 
        "order_id" : "S12348", 
        "subscription_type" : "Alternate", 
        "_id" : "56a31c29d55894ec15eac1d0", 
        "ordered_at" : "2016-01-23T06:22:33.307Z", 
        "status" : "UnderProcess"
    }, 
    "area_name" : "kodambakkam", 
    "name" : "Ganesh", 
    "email" : "ganesh@gmail.com", 
    "mobile_no" : "9042391491", 
    "date" : "2016-01-21T11:10:05.074Z"
}