mongo db查询聚合

Question

这是我的数据:在mongodb中

db.population.insertMany([
    {
        "country" :"India",
        "state" : [
            {"Punjab" : { 
                            "male" : 50 ,
                            "female" : 50
                        }
            }, 
            {"Haryana" : { 
                            "male" : 150 ,
                            "female" : 140
                        }
            }, 
            {"UP" : { 
                            "male" : 120 ,
                            "female" : 160
                        }
            },
        ]
    }, {
        "country" :"Shri lanka",
        "state" : [
            {"Eastern" : { 
                            "male" : 30 ,
                            "female" : 40
                        }
            }, 
            {"North Central" : { 
                            "male" : 250 ,
                            "female" : 240
                        }
            }, 
            {"Uva" : { 
                            "male" : 120 ,
                            "female" : 260
                        }
            },
        ]
    }

])

我希望这是查询结果中的ans

Country : "shri lanka", "state" : "Eastern", total: 70
Country : "North Central", "state" : "Eastern", total: 490
Country : "Uva", "state" : "Eastern", total: 380
Country : "Haryana", "state" : "Punjab", total: 190
Country : "India", "state" : "Punjab", total: 100

这个也是

   Country : "India",  total: 500  total sum
   Country : "shri lanka",  total: 2541 total sum

Answer 1

对于第一批人

db.population.aggregate([
  {$unwind:"$state"},
  {$project:{"country":1,"state":{$objectToArray: "$state"}}},
  {$unwind:"$state"}, 
  {$project:{"country":"$country","state":"$state.k",
  "total":{$sum:["$state.v.male","$state.v.female"]}}},
  { $group: { _id: "$country" , "total" : {$sum: "$total"}}}
])

为2个人

db.population.aggregate([
  {$unwind:"$state"},
  {$project:{"country":1,"state":{$objectToArray: "$state"}}},
  {$unwind:"$state"}, 
  {$project:{"country":"$country","state":"$state.k",
  "total":{$sum:["$state.v.male","$state.v.female"]}}},
  { $group: { _id: "$country" , "total" : {$sum: "$total"}}}
])