如何使用$ filter获得数组字段的过滤元素

我在MongoDB中有一个列车集合，它有以下几行：

{ "_id" : ObjectId("594a441fcbd8f815dc42436d"), "trainnum" : "011Ф", "startplace" : "Tashkent", "destination" : "Samarkand", "weeks" : [ "1", "2", "3" ], "vagons" : [ { "_id" : ObjectId("594a6a42231e5912342ff903"), "numvag" : "01K", "seatcount" : "30", "reserves" : [ { "numseats" : "1-10", "numreserve" : "1", "_id" : ObjectId("594a6a42231e5912342ff904") } ], "date2" : ISODate("2017-06-30T00:00:00Z"), "date1" : ISODate("2017-06-05T00:00:00Z") }, { "_id" : ObjectId("594a6c0d231e5912342ff905"), "numvag" : "02C", "seatcount" : "01-10", "reserves" : [ { "numseats" : "01-10", "numreserve" : "05", "_id" : ObjectId("594a6c0d231e5912342ff906") } ], "date2" : ISODate("2017-06-21T00:00:00Z"), "date1" : ISODate("2017-06-25T00:00:00Z") } ], "date2" : ISODate("2017-07-30T00:00:00Z"), "date1" : ISODate("2017-06-01T00:00:00Z"), "__v" : 0 } { "_id" : ObjectId("594a69c4231e5912342ff900"), "trainnum" : "012A", "startplace" : "Tashkent", "destination" : "Samarkand", "updated_at" : ISODate("2017-06-21T12:42:44.893Z"), "weeks" : [ "1", "2", "3", "4" ], "vagons" : [ { "_id" : ObjectId("594b54fe0925d110180abf7b"), "numvag" : "01K", "seatcount" : "30", "reserves" : [ ], "date2" : ISODate("2017-07-23T00:00:00Z"), "date1" : ISODate("2017-06-30T00:00:00Z") }, { "_id" : ObjectId("594b55ede16d1908b8129b42"), "numvag" : "02L", "seatcount" : "40", "reserves" : [ ], "date2" : ISODate("2017-07-11T00:00:00Z"), "date1" : ISODate("2017-06-29T00:00:00Z") } ], "date2" : ISODate("2017-07-30T00:00:00Z"), "date1" : ISODate("2017-06-01T00:00:00Z"), "__v" : 0 } 

如何检索所有具有date1（vagon date1）>当前date（22.06.2017）（Vagons.date1>当前date）的迷宫的列车。 结果应该是这样的：

 { "_id" : ObjectId("594a441fcbd8f815dc42436d"), "trainnum" : "011Ф", "startplace" : "Tashkent", "destination" : "Samarkand" "weeks" : [ "1", "2", "3" ], "vagons" : [ { "_id" : ObjectId("594a6c0d231e5912342ff905"), "numvag" : "02C", "seatcount" : "01-10", "reserves" : [ { "numseats" : "01-10", "numreserve" : "05", "_id" : ObjectId("594a6c0d231e5912342ff906") } ], "date2" : ISODate("2017-06-21T00:00:00Z"), "date1" : ISODate("2017-06-25T00:00:00Z") } ], "date2" : ISODate("2017-07-30T00:00:00Z"), "date1" : ISODate("2017-06-01T00:00:00Z"), "__v" : 0 } `{ "_id" : ObjectId("594a69c4231e5912342ff900"), "trainnum" : "012A", "startplace" : "Tashkent", "destination" : "Samarkand", "updated_at" : ISODate("2017-06-21T12:42:44.893Z"), "weeks" : [ "1", "2", "3", "4" ], "vagons" : [ { "_id" : ObjectId("594b54fe0925d110180abf7b"), "numvag" : "01K", "seatcount" : "30", "reserves" : [ ], "date2" : ISODate("2017-07-23T00:00:00Z"), "date1" : ISODate("2017-06-30T00:00:00Z") }, { "_id" : ObjectId("594b55ede16d1908b8129b42"), "numvag" : "02L", "seatcount" : "40", "reserves" : [ ], "date2" : ISODate("2017-07-11T00:00:00Z"), "date1" : ISODate("2017-06-29T00:00:00Z") } ], "date2" : ISODate("2017-07-30T00:00:00Z"), "date1" : ISODate("2017-06-01T00:00:00Z"), "__v" : 0 }` 

Answer 1

只需在该字段上应用$filter条件即可。 使用$gt作为"cond"参数。

如果您没有MongoDB 3.4或更高版本，那么使用$project而不是$addFields并且只需在投影中包含所有其他字段：

 Train.aggregate([ { "$match": { "vagons.date1": { "$gte": new Date("2017-06-22") } }}, { "$addFields": { "vagons": { "$filter": { "input": "$vagons", "as": "v", "cond": { "$gt": [ "$$v.date1", new Date("2017-06-22") ] } } } }} ]) 

给出输出：

 { "_id" : ObjectId("594a441fcbd8f815dc42436d"), "trainnum" : "011Ф", "startplace" : "Tashkent", "destination" : "Samarkand", "weeks" : [ "1", "2", "3" ], "vagons" : [ { "_id" : ObjectId("594a6c0d231e5912342ff905"), "numvag" : "02C", "seatcount" : "01-10", "reserves" : [ { "numseats" : "01-10", "numreserve" : "05", "_id" : ObjectId("594a6c0d231e5912342ff906") } ], "date2" : ISODate("2017-06-21T00:00:00Z"), "date1" : ISODate("2017-06-25T00:00:00Z") } ], "date2" : ISODate("2017-07-30T00:00:00Z"), "date1" : ISODate("2017-06-01T00:00:00Z"), "__v" : 0 } { "_id" : ObjectId("594a69c4231e5912342ff900"), "trainnum" : "012A", "startplace" : "Tashkent", "destination" : "Samarkand", "updated_at" : ISODate("2017-06-21T12:42:44.893Z"), "weeks" : [ "1", "2", "3", "4" ], "vagons" : [ { "_id" : ObjectId("594b54fe0925d110180abf7b"), "numvag" : "01K", "seatcount" : "30", "reserves" : [ ], "date2" : ISODate("2017-07-23T00:00:00Z"), "date1" : ISODate("2017-06-30T00:00:00Z") }, { "_id" : ObjectId("594b55ede16d1908b8129b42"), "numvag" : "02L", "seatcount" : "40", "reserves" : [ ], "date2" : ISODate("2017-07-11T00:00:00Z"), "date1" : ISODate("2017-06-29T00:00:00Z") } ], "date2" : ISODate("2017-07-30T00:00:00Z"), "date1" : ISODate("2017-06-01T00:00:00Z"), "__v" : 0 }