Mongodb外层结构转内层

插入语句

db.resultsCollection.insert([
{ "timeStamp" : 1341834988666, "label" : "sharon", "responseCode" : "200", "value" : 10, "success" : "true"},
{ "timeStamp" : 1341834988696, "label" : "sharon", "responseCode" : "200", "value" : 35, "success" : "false"},
{ "timeStamp" : 1341834988676, "label" : "paul", "responseCode" : "200", "value" : 60, "success" : "true"},
{ "timeStamp" : 1341834988166, "label" : "paul", "responseCode" : "200", "value" : 40, "success" : "true"},
{ "timeStamp" : 1341834988686, "label" : "paul", "responseCode" : "404", "value" : 15, "success" : "true"},
{ "timeStamp" : 1341834988266, "label" : "paul", "responseCode" : "404", "value" : 99, "success" : "false"}
])

查询

db.sales.aggregate(
   [
     {
       $group:
         {
           _id: { day: { $dayOfYear: "$date"}, year: { $year: "$date" } },
           itemsSold: { $push:  { item: "$item", quantity: "$quantity" } }
         }
     }
   ]
)

结果

// 1
{
    "_id": {
        "day": NumberInt("46"),
        "year": NumberInt("2014")
    },
    "itemsSold": [
        {
            "item": "abc",
            "quantity": 10
        },
        {
            "item": "xyz",
            "quantity": 10
        },
        {
            "item": "xyz",
            "quantity": 5
        },
        {
            "item": "xyz",
            "quantity": 10
        }
    ]
}

// 2
{
    "_id": {
        "day": NumberInt("34"),
        "year": NumberInt("2014")
    },
    "itemsSold": [
        {
            "item": "jkl",
            "quantity": 1
        },
        {
            "item": "xyz",
            "quantity": 5
        }
    ]
}

// 3
{
    "_id": {
        "day": NumberInt("1"),
        "year": NumberInt("2014")
    },
    "itemsSold": [
        {
            "item": "abc",
            "quantity": 2
        }
    ]
}