如何在 mongoose/mongodb 中对子文档数组进行排序？

Question

用户（mongodb 文档）

{
  "_id": "5bccfb7515bc6d0c6872ed91",
  "notification": {
    "notidata": [
      {
        "data": {
          "para": "Your Ad '1' has been successfully submitted."
        },
        "notistatus": false,
        "_id": "5be35d89113aec40c4ca7517",
        "notidate": "2018-11-07T21:47:53.803Z"
      },
      {
        "data": {
          "para": "Your Ad '2' has been successfully submitted."
        },
        "notistatus": false,
        "_id": "5be35d92113aec40c4ca7519",
        "notidate": "2018-11-07T21:48:02.729Z"
      }
    ],
    "counter": 4
  },
  "ads": [],
  "username": "mesam",
  "email": "mesam@hotmal.com",
  "password": "0",
  "country": "AZE",
  "createdOn": "2018-10-21T22:19:33.377Z",
  "__v": 0
}

route.js

User.findOneAndUpdate({ _id: user._id }, { $push: { "notification.notidata": { "data.para": "Your Ad " + "'" + thisad.heading + "'" + " has been successfully submitted."} } }, { new: true }, function (err, df) { ....

我希望notidata 按notidate 排序。使用 $postion: 0 不起作用。 $sort: notidate: -1也没有

* $position 尝试失败*

User.findOneAndUpdate({ _id: user._id }, { $push: { "notification.notidata": { "data.para": "Your Ad " + "'" + thisad.heading + "'" + " has been successfully submitted.", "$position": 0} } }, { new: true }, function (err, df) {....

$sort 尝试失败

User.findOneAndUpdate({ _id: user._id }, { $push: { "notification.notidata": { "data.para": "Your Ad " + "'" + thisad.heading + "'" + " has been successfully submitted.", "$sort": {"notification.notidata.notidate": -1}} } }, { new: true }, function (err, df) {....

Answer 1

您必须将$sort 与$each 运算符一起使用，然后您只需指定嵌套字段的名称（而不是您的示例中的整个路径），尝试：

User.findOneAndUpdate({ _id: user._id }, { 
    $push: {
        "notification.notidata": {
            "$each": [ { data: { para: "Your Ad " + "'" + thisad.heading + "'" + " has been successfully submitted." } } ],
            "$sort": {"notidate": -1}
        }
    }
}, {new: true})