MongoDB - 如何在查询中添加多个聚合

MongoDB - How do I add multiple aggregations in query

我有以下查询:

[
  {
    "$group": {
      "_id": "$Region",
      "Total Sales": {
        "$sum": "$Sales"
      },
      "Average Sales": {
        "$avg": "$Sales"
      }
    }
  }
]

此 returns 响应格式如下:

[
  {
    "_id": "Canada",
    "Total Sales": 66928.17,
    "Average Sales": 174.292109375,
  }
  .....
]

如何重构查询以获得以下格式的响应:

[{
    "_id": "Canada",
    "Sales":{"Total":66928.17, "Average":174.292109375},
  }
  ......
]

到目前为止我已经尝试过这样但它不起作用:

{
  "$group": {
    "_id": "$Region",
    "Sales": {
      "Total":{
          "$sum": "$Sales"
      },
      "Average":{
          "$avg": "$Sales"
      }
    }
  }
}

使用$project修饰输出文档。

db.collection.aggregate([
  {
    "$group": {
      "_id": "$Region",
      "total": {
        "$sum": "$Sales"
      },
      "average": {
        "$avg": "$Sales"
      }
    }
  },
  {
    $project: {
      "Sales": {
        "Total": "$total",
        "Average": "$average"
      }
    }
  }
])

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