mongodb - MongoDB如何计算子文档总数大于3且子文档值之和大于15000的地方

Question

样本数据：

{
        "_id" : "5e7b0e1c4669fe48ea07b63a",
        "isActive" : false,
        "balance" : -1503.89,
        "age" : 27,
        "eyeColor" : "green",
        "name" : "Allison Alvarez",
        "gender" : "female",
        "company" : "RONELON",
        "email" : "[e-mail]",
        "phone" : "[phone]",
        "address" : "583 Sumpter Street, Stewartville, West Virginia, 110",
        "registered" : "2016-10-19T11:45:39 -01:00",
        "outstandingloans" : [
                {
                        "id" : 0,
                        "balance" : -710.65
                },
                {
                        "id" : 1,
                        "balance" : -2979.51
                },
                {
                        "id" : 2,
                        "balance" : -2520.79
                },
                {
                        "id" : 3,
                        "balance" : -3488.78
                }
        ]
}

我正在尝试查找拥有超过 3 笔未偿贷款且余额总和小于 -15000 的男性人数。

到目前为止我的工作是：

db.defaulters.aggregate([
    {$match: { "gender" : "male"}},
    {$project: {_id: "$name", loansGrt3: {$gte: [{$size: '$outstandingloans'}, 3]} }}
]);

和

db.defaulters.find( 
{ $where: "this.outstandingloans.length > 3"}
).count();

标签： mongodbmongodb-query

Answer 1

db.defaulters.aggregate([
  { $unwind: "$outstandingloans" },
  { $project: 
       { _id:1, 
         size_of_outstandingloans: { $size: "$outstandingloans"},
         totalBalance: { $sum: "$outstandingloans.amount" }
       }         
  },
  { $match: { $and: [ {"size_of_outstandingloans": {$gt: 3} },  {"totalBalance": {$lt: -15000} }] }}
])