特定日期范围内的MongoDB聚合查找对象

我有一些用户和他们的订单：

db={
  orders: [
    {
      "_id": "wJNEiSYwBd5ozGtLX",
      "orderId": 52713,
      "retailerId": 1320,
      "createdAt": ISODate("2020-01-31T04:34:13.790Z"),
      "status": "closed"
    },
    {
      "_id": "wJNEiSYwBd5ozGtLX2",
      "orderId": 52714,
      "retailerId": 1320,
      "createdAt": ISODate("2021-03-31T04:34:13.790Z"),
      "status": "closed"
    }
  ],
  users: [
    {
      "_id": "2gSznevqwkGTxLRvL",
      "createdAt": ISODate("2018-04-10T08:33:13.455Z"),
      "username": "retailer@gmail.com",
      "info": {
        "retailerId": 1320,
        
      },
      "settings": {},
      "status": "active",
      
    }
  ]
}

如果我尝试将订单聚合到用户中：

 db.users.aggregate([
      {
        "$lookup": {
          "from": "orders",
          "localField": "info.retailerId",
          "foreignField": "retailerId",
          "as": "orders"
        }
      },
    
    ])

我可以像这样将所有订单合并到用户中：

[
  {
    "_id": "2gSznevqwkGTxLRvL",
    "createdAt": ISODate("2018-04-10T08:33:13.455Z"),
    "info": {
      "retailerId": 1320
    },
    "orders": [
      {
        "_id": "wJNEiSYwBd5ozGtLX",
        "createdAt": ISODate("2020-01-31T04:34:13.79Z"),
        "orderId": 52713,
        "retailerId": 1320,
        "status": "closed"
      },
      {
        "_id": "wJNEiSYwBd5ozGtLX2",
        "createdAt": ISODate("2021-03-31T04:34:13.79Z"),
        "orderId": 52714,
        "retailerId": 1320,
        "status": "closed"
      }
    ],
    "settings": {},
    "status": "active",
    "username": "retailer@gmail.com"
  }
]

但我只想合并上个月的订单，而不是将所有订单合并到用户中。 如何指定日期范围

演示-

要在两个集合之间执行不相关的子查询，以及允许除单个相等匹配之外的其他联接条件，$lookup stage具有以下语法：

在管道样式中使用$lookup-

db.users.aggregate([
  {
    "$lookup": {
      "from": "orders",
      "let": { "rId": "$info.retailerId" },
      "pipeline": [
        {
          $match: {
            $expr: { $eq: [ "$retailerId","$$rId" ] },
            createdAt: { $gte: ISODate("2021-03-01T00:00:00.000Z"), $lt: ISODate("2021-04-01T00:00:00.000Z") } // write date range query here
          }
        }
      ],
      "as": "orders"
    }
  }
])