使用 MongoDB 從另一個集合中獲取數據

Question

使用 MongoDB 我得到了銷售數據，我得到了銷售的客戶，但我只得到了他們的“_id”，但我需要得到他們的數據，比如名字。 這是可能的？ 這是我對我的銷售集合所做的查詢，其中客戶是銷售對象：

db.sales.aggregate([
  {
    $group: {
      _id: {
        month: {
          $month: "$createdAt"
        },
        year: {
          $year: "$createdAt"
        },
        dayOfWeek: {
            $dayOfWeek: "$createdAt"
        },
        stringDay: { 
            $dateToString: 
            { format: "%Y-%m-%d", date: "$createdAt"}
        },
        week: {
            $isoWeek: "$createdAt"
        }
      },
      paymentType: { $first: '$paymentType' },
      client: { $first: '$clientId' },
      total: { $sum: '$total'},
      count: { $sum: 1 },
      totalAverage: { $avg: '$total'},
    }
  },
  {
    $project: {
      total:  { $round: [ "$total", 2 ] },
      year: "$_id.year",
      date: "$_id.date",
      week: "$_id.week",
      numVentas: "$count",
      month: "$_id.month",
      dayOfWeek: "$_id.dayOfWeek",
      stringDay:"$_id.stringDay",
      count: "$count",
      paymentType: "$paymentType",
      client: "$client",
      totalAverage: { $round: [ "$totalAverage", 2 ] },
      stringMonth: {
        $arrayElemAt: [
          [
            "",
            "Jan",
            "Feb",
            "Mar",
            "Apr",
            "May",
            "Jun",
            "Jul",
            "Aug",
            "Sep",
            "Oct",
            "Nov",
            "Dec"
          ],
          "$_id.month"
        ]
      },
      stringWeek: {
        $switch: {
            branches:[
                { case: { $eq: ["$_id.dayOfWeek", 1] }, then: "Lunes" },
                { case: { $eq: ["$_id.dayOfWeek", 2] }, then: "Martes" },
                { case: { $eq: ["$_id.dayOfWeek", 3] }, then: "Miércoles" },
                { case: { $eq: ["$_id.dayOfWeek", 4] }, then: "Jueves" },
                { case: { $eq: ["$_id.dayOfWeek", 5] }, then: "Viernes" },
                { case: { $eq: ["$_id.dayOfWeek", 6] }, then: "Sábado" },
                { case: { $eq: ["$_id.dayOfWeek", 7] }, then: "Domingo" }
            ],
            default: "Día desconocido"
            }
        }
    }
  },
  {
    $group: {
        _id:  { month: "$month", stringMonth: "$stringMonth", year: "$year"},
        count: { $sum: "$count" },
        total: { $sum: "$total" },
        totalAverage: { $sum: "$totalAverage" },
        sales: {
            $push: { 
                client: "$client",
                paymentType: "$paymentType",
                numberDay: "$dayOfWeek",
                week: "$week",
                stringWeek: "$stringWeek",
                date: "$stringDay",
                total: "$total",
                count: "$count",
                totalAverage: { $round: [ "$totalAverage", 2 ] }  
            }
        }
    }
  },
  {
    $group: {
        _id: "$_id.year",
        monthsWithSales: { $sum: 1 },
        count: { $sum: "$count" },
        total: { $sum: "$total" },
        totalAverage: { $sum: "$totalAverage" },
        sales: {
            $push: {
                month: "$_id.month",
                stringMonth: "$_id.stringMonth",
                count: "$count",
                total: "$total",
                totalAverage: "$totalAverage",
                sales:"$sales"
            }
        }
    }
  }
  
])

這只給我帶來了銷售客戶的“_id”，但我還需要獲取其他數據，例如客戶集合中的客戶名稱：

    "_id": 2022,
    "monthsWithSales": 4,
    "count": 57,
    "total": 22324.8,
    "totalAverage": 7765.799999999999,
    "sales": [
      {
        "month": 12,
        "stringMonth": "Dec",
        "count": 33,
        "total": 12587.6,
        "totalAverage": 4074.5,
        "sales": [
          {
            **"client": {
              "$oid": "63890f616d8780e8608266f5"
            },**
            "paymentType": "CASH",

Answer 1

在 MongoDB 聚合中，您可以為此使用 Lookup 運算符。 參考：- 在 MongoDB 網站上閱讀 Lookup 。

如果您使用的是 Mongoose，您也可以使用Populate 方法。

如果它們有一個公共字段，這兩個都從另一個集合中獲取文檔並添加到當前集合中。 在這里討論可能會很復雜。 所以請參考官方文檔查找或填充