具有 mongodb 聚合的多个组

Question

我正在尝试对这些数据使用 mongoDb 聚合：

"_id": ObjectId("598dbd301ab6476e5b15e05e"),
"updated_at": ISODate("2017-08-11T14:20:32.865Z"),
"created_at": ISODate("2017-08-11T14:20:32.865Z"),
"action": ObjectId("59760749a398cb323cf1c051"),
"subAction": ObjectId("5980c3807a8cb300110d87d3"),
"person": ObjectId("598dbd2f1ab6476e5b15e05b"),
"session": ObjectId("598dbd2f1ab6476e5b15e05c"),
"dateAccomplish": ISODate("2017-08-11T14:20:32Z"),
"createdBy": ObjectId("595f8426645bf5f47366fb29"),
"updatedBy": ObjectId("595f8426645bf5f47366fb29"),

我想要做的是我需要检索 2 个组。它必须按actions 和subactions 分组。

预期的输出数据如下所示：

movactions: [
{
     _id: $created_at,
     count: ?,
     data:[
         {
             _id: "$action",
             count: 3,
             data: [
                {
                    _id: "$subaction",
                    count: 2
                }
             ]
          }
     ]
},
]

有很多子动作都有一个动作，我想将每个动作与列出的子动作聚合起来

Answer 1

要按多个字段分组，$group 应与复合 _id 一起应用多次，并在下一组中逐渐减少：

db.collection.aggregate([
    {$group:{
        _id:{created_at:"$created_at", action:"$action", subAction:"$subAction"},
        count: {$sum:1}
    }},
    {$group:{
        _id:{created_at:"$_id.created_at", action:"$_id.action"},
        count: {$sum:1},
        data: {$push:{_id: "$_id.subAction", count:"$count"}}
    }},
    {$group:{
        _id:"$_id.created_at",
        count: {$sum:1},
        data: {$push:{_id: "$_id.action", count:"$count", data:"$data"}}
    }}, 
    {$project: {
        _id:0,
        created_at:"$_id", 
        count:1, 
        data:1
    }}
]);