mongodb - Mongodb 聚合不工作

Question

我在 mongo 集合 (datacollection) 中有以下数据:

{
  "_id": ObjectId("54980efef7db7d9b018d375b"),
  "sub_id": "1234567890",
  "points": "10",
  "oid": "1",
  "name": "test",
  "app": "e53abc6d12fea63c80e4c2e1d49e",
  "source": "mysource",
  "product_name": "browser",
  "added": ISODate("2014-12-22T12:30:54.618Z"),
  "added_human": "2014-12-22 06:30:54",
  "checked": true
}

我实际上需要找出按日期分组的点数总和。 SQL 查询将如下所示: SELECT DATE(added) as point_date, SUM(points) AS total_points FROM mytable WHERE added between 'from' AND 'to' GROUP BY DATE(added).

所以我正在使用以下聚合:

db.datacollection.aggregate(
    { 
        $match:{
            "added" : {$gte:ISODate("2014-12-01"), $lt:ISODate("2014-12-25")},   
            "source":"mysource"  
        },   
        $group : {
            "_id" : { month: { $month: "$added" }, day: { $dayOfMonth: "$added" }, year: { $year: "$added" } },
            "total_points":{$sum:"$points"}   
        }  
    }  
);

但是这是显示

"errmsg" : "exception: A pipeline stage specification object must contain exactly one field.",

如何解决这个问题，或者是否有更好的方法来进行此计算？？

Answer 1

使用这个:

db.datacollection.aggregate(
    { 
        $match:{
            "added" : {$gte:ISODate("2014-12-01"), $lt:ISODate("2014-12-25")},   
            "source":"mysource"  
        }
    },   
    {   $group : {
            "_id" : { month: { $month: "$added" }, day: { $dayOfMonth: "$added" }, year: { $year: "$added" } },
            "total_points":{$sum:"$points"}   
        }  
    }  
);

您应该使用这种格式({} 对中的每个管道)

db.collection.aggrgation ( 
   { $group: ....},
   { $match : .... },
   ...
})

但你用过:

db.collection.aggrgation ( 
   { $group: ....,
     $match : ....,
     ...
   }
})