Mongoose Schema - 如何添加排序属性

Question

我目前正在构建一个 Web 应用程序，您可以在其中创建带有歌词 objectId 数组的设置列表（数组），然后您可以按照您的需要对其进行排序/排序。因此，如果您希望第 3 个列表项成为第一个，则只需将其拖放到第一行即可。

我的猫鼬模式现在有问题。我正在寻找一种方法来实现 order 属性或允许我根据歌词的位置添加诸如 0 或 1 之类的 order 值的方法。你们有人知道如何最好地执行这样的命令吗？

这是我的架构的副本。目前，歌词是一组歌词对象 ID。但在那里我也需要一个“订单”，以便我可以根据订单值对数组进行排序。

const mongoose = require("mongoose");

const SetlistSchema = new mongoose.Schema({
    setlistName: { type: String, required: true },
    lastEdited: { type: Date },
    createdAt: { type: Date, default: Date.now },
    lyrics: [{
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Lyric'
    }],
    author: {
        id: {
            type: mongoose.Schema.Types.ObjectId,
            ref: "User"
        },
        username: String
    }
});

module.exports = mongoose.model("Setlist", SetlistSchema);

这是歌词架构。

const mongoose = require("mongoose");

const LyricSchema = new mongoose.Schema({
    lyricName: { type: String, required: true },
    lyricContent: { type: String, required: true },
    lastEdited: { type: Date },
    createdAt: { type: Date, default: Date.now },
    author: {
        id: {
            type: mongoose.Schema.Types.ObjectId,
            ref: "User"
        },
        username: String
    }
});

module.exports = mongoose.model("Lyric", LyricSchema);

如果添加订单号不是最佳做法，那么您可以推荐什么方法来跟踪用户希望歌词显示的顺序？

Answer 1

您可以使用聚合框架按顺序字段对歌词进行排序。您首先需要添加一个 Number 类型的排序字段。

Setlist.aggregate([
  {
    $unwind: "$lyrics"
  },
  {
    $lookup: {
      from: "lyrics",  // MUST be the PHYSICAL collection name
      localField: "lyrics",
      foreignField: "_id",
      as: "lyrics"
    }
  },
  {
    $sort: {
      "lyrics.order": 1
    }
  },
  {
    "$group": {
      "_id": "$_id",
      "lyrics": {
        "$push": "$lyrics"
      },
      "allFields": {
        "$first": "$$ROOT"
      }
    }
  },
  {
    "$replaceRoot": {
      "newRoot": {
        "$mergeObjects": [
          "$allFields",
          {
            "lyrics": "$lyrics"
          }
        ]
      }
    }
  }
])

Playground

示例文件：

db={
  "lists": [
    {
      "_id": ObjectId("5a934e000102030405000000"),
      "setlistName": "list1",
      "lastEdited": ISODate("2020-03-18T23:11:56.443+03:00"),
      "createdAt": ISODate("2020-03-15T23:11:56.443+03:00"),
      "lyrics": [
        ObjectId("6a934e000102030405000000"),
        ObjectId("6a934e000102030405000001"),
        ObjectId("6a934e000102030405000002")
      ]
    },
    {
      "_id": ObjectId("5a934e000102030405000001"),
      "setlistName": "list2",
      "lastEdited": ISODate("2020-03-11T23:11:56.443+03:00"),
      "createdAt": ISODate("2020-03-11T23:11:56.443+03:00"),
      "lyrics": [
        ObjectId("6a934e000102030405000003"),
        ObjectId("6a934e000102030405000004")
      ]
    }
  ],
  "lyrics": [
    {
      "_id": ObjectId("6a934e000102030405000000"),
      "name": "Lyric 1",
      "order": 3
    },
    {
      "_id": ObjectId("6a934e000102030405000001"),
      "name": "Lyric 2",
      "order": 1
    },
    {
      "_id": ObjectId("6a934e000102030405000002"),
      "name": "Lyric 3",
      "order": 2
    },
    {
      "_id": ObjectId("6a934e000102030405000003"),
      "name": "Lyric 4",
      "order": 2
    },
    {
      "_id": ObjectId("6a934e000102030405000004"),
      "name": "Lyric 5",
      "order": 1
    }
  ]
}

输出：（如您所见，歌词按顺序字段值排序）

[
  {
    "_id": ObjectId("5a934e000102030405000000"),
    "createdAt": ISODate("2020-03-15T20:11:56.443Z"),
    "lastEdited": ISODate("2020-03-18T20:11:56.443Z"),
    "lyrics": [
      [
        {
          "_id": ObjectId("6a934e000102030405000001"),
          "name": "Lyric 2",
          "order": 1
        }
      ],
      [
        {
          "_id": ObjectId("6a934e000102030405000002"),
          "name": "Lyric 3",
          "order": 2
        }
      ],
      [
        {
          "_id": ObjectId("6a934e000102030405000000"),
          "name": "Lyric 1",
          "order": 3
        }
      ]
    ],
    "setlistName": "list1"
  },
  {
    "_id": ObjectId("5a934e000102030405000001"),
    "createdAt": ISODate("2020-03-11T20:11:56.443Z"),
    "lastEdited": ISODate("2020-03-11T20:11:56.443Z"),
    "lyrics": [
      [
        {
          "_id": ObjectId("6a934e000102030405000004"),
          "name": "Lyric 5",
          "order": 1
        }
      ],
      [
        {
          "_id": ObjectId("6a934e000102030405000003"),
          "name": "Lyric 4",
          "order": 2
        }
      ]
    ],
    "setlistName": "list2"
  }
]