我正在尝试在 Mongodb 中执行查询。我要执行的查询是根据日期(过去 7 天)查找集合中的所有订单，然后将价格与每个订单的嵌套对象相加。到目前为止，我有以下代码:

收集/数据

{
    "_id" : "g32fYpydfSFDbFkoi",
    "orderNumber" : 1234,
    "createdAt" : ISODate("2016-01-12T13:50:17.559Z"),
    "productsInOrder" : [
        {
            "category" : "ambient",
            "item" : 23982,
            "desc" : "Ergonomic Cotton Sausages",
            "quantity" : "456",
            "price" : "0.54",
            "lineprice" : "246.24",
            "_id" : "BdD4QnM7sYTwBpLds"
        },
        {
            "category" : "ambient",
            "item" : 15336,
            "desc" : "Rustic Wooden Chicken",
            "quantity" : "2",
            "price" : "1.87",
            "lineprice" : "3.74",
            "_id" : "PvtSxi2MfYrZNTD6f"
        },
        {
            "category" : "chilled",
            "item" : 57584,
            "desc" : "Unbranded Soft Chicken",
            "quantity" : "3",
            "price" : "4.69",
            "lineprice" : "14.07",
            "_id" : "ppkECqmhPvg7pQcgB"
        },
        {
            "category" : "ambient",
            "item" : 71168,
            "desc" : "Rustic Rubber Computer",
            "quantity" : "5",
            "price" : "3.04",
            "lineprice" : "15.20",
            "_id" : "bZtr5dkvsG92YtLoe"
        },
        {
            "category" : "frozen",
            "item" : 87431,
            "desc" : "Unbranded Granite Sausages",
            "quantity" : "5678",
            "price" : "1.98",
            "lineprice" : "11242.44",
            "_id" : "ZKur3rHhtCLsWiENr"
        },
        {
            "category" : "frozen",
            "item" : 75007,
            "desc" : "Practical Frozen Towels",
            "quantity" : "678",
            "price" : "1.19",
            "lineprice" : "806.82",
            "_id" : "g78zvzoE8wJkciD9C"
        },
        {
            "category" : "frozen",
            "item" : 84721,
            "desc" : "Fantastic Metal Hat",
            "quantity" : "34",
            "price" : "1.83",
            "lineprice" : "62.22",
            "_id" : "4aqxBWhXy5cabbbiM"
        },
        {
            "category" : "frozen",
            "item" : 72240,
            "desc" : "Fantastic Granite Towels",
            "quantity" : "1",
            "price" : "2.94",
            "lineprice" : "2.94",
            "_id" : "MQD2LNv36mE3BWvZJ"
        },
        {
            "category" : "chilled",
            "item" : 89448,
            "desc" : "Intelligent Concrete Towels",
            "quantity" : "6678",
            "price" : "0.42",
            "lineprice" : "2804.76",
            "_id" : "AjRrxFT4mfpxuciC4"
        },
        {
            "category" : "chilled",
            "item" : 57584,
            "desc" : "Unbranded Soft Chicken",
            "quantity" : "1111",
            "price" : "4.69",
            "lineprice" : "5210.59",
            "_id" : "4yBspve6mBNNzqDnZ"
        }
    ]
  }

查询

Orders.aggregate([
    { $match: { 'createdAt': { $gt: pastDate }}},
    { $unwind: '$productsInOrder' },
    {
      $group: {
        _id: null,
        price: {
          $sum: '$productsInOrder.price'
        }
      }
    }
]);

我最终想要的是输出最近7天每天的总价。谁能帮我指出正确的方向？非常感谢。

最佳答案

首先， $sum 运算符将忽略非数字值，并且 productsInOrder.price 子文档字段是字符串类型，因此最好将其转换为数字字段。

完成后，要输出过去 7 天每天的总价，请将 group by key 更改为使用 $dayOfMonth 运算符，它在 7 天的范围内每天对您的文档进行分组，如下所示

Orders.aggregate([
    { "$match": { "createdAt": { "$gt": pastDate } } },
    { "$unwind": "$productsInOrder" },
    {
        "$group": {
            "_id": {
                "day": { "$dayOfMonth": "$createdAt" }
            },
            "price": { "$sum": "$productsInOrder.price" }
        }
    }    
]);

关于javascript - Mongodb 聚合基于过去的日期，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34745934/