Mongodb 嵌套集合检索

Question

我有一个 MongoDB 集合，格式如下：

{
        "_id" : ObjectId("5b6b112d1bbd972848b97df4"),
        "team" : "Switzerland",
        "Game" : [
                {
                        "City" : "Nizhny Novgorod",
                        "T2N" : "Costa Rica",
                        "T1N" : "Switzerland",
                        "ST" : "Nizhny Novgorod Stadium",
                        "T1S" : "2",
                        "Date" : "6/27/2018",
                        "T2S" : "2"
                },
                {
                        "City" : "Kaliningrad",
                        "T2N" : "Serbia",
                        "T1N" : "Switzerland",
                        "ST" : "Kaliningrad Stadium",
                        "T1S" : "2",
                        "Date" : "6/22/2018",
                        "T2S" : "1"
                },
                {
                        "City" : "Rostov-on-Don",
                        "T2N" : "Brazil",
                        "T1N" : "Switzerland",
                        "ST" : "Rostov Arena",
                        "T1S" : "1",
                        "Date" : "6/17/2018",
                 }]
}

我正在尝试运行以下查询： db.test.find({"Game.T1S":{$gte:3}}).漂亮() 但是这个 returns 数据格式如下：

{
        "_id" : ObjectId("5b6b112d1bbd972848b97df4"),
        "team" : "Switzerland",
        "Game" : [
                {
                        "City" : "Nizhny Novgorod",
                        "T2N" : "Costa Rica",
                        "T1N" : "Switzerland",
                        "ST" : "Nizhny Novgorod Stadium",
                        "T1S" : "2",
                        "Date" : "6/27/2018",
                        "T2S" : "2"
                },
                {
                        "City" : "Kaliningrad",
                        "T2N" : "Serbia",
                        "T1N" : "Switzerland",
                        "ST" : "Kaliningrad Stadium",
                        "T1S" : "2",
                        "Date" : "6/22/2018",
                        "T2S" : "1"
                },
                {
                        "City" : "Rostov-on-Don",
                        "T2N" : "Brazil",
                        "T1N" : "Switzerland",
                        "ST" : "Rostov Arena",
                        "T1S" : "1",
                        "T2S" : "3"
                        "Date" : "6/17/2018",
                 }]
}

我希望结果只是

db.test.find({"Game.T1S":{$gte:3}}).漂亮() 但是这个 returns 数据格式如下：

{
        "_id" : ObjectId("5b6b112d1bbd972848b97df4"),
        "team" : "Switzerland",
        "Game" : [
                {
                        "City" : "Rostov-on-Don",
                        "T2N" : "Brazil",
                        "T1N" : "Switzerland",
                        "ST" : "Rostov Arena",
                        "T1S" : "1",
                        "T2S" : "3"
                        "Date" : "6/17/2018",
                 }]
}

也就是说，游戏的结果应该只包含 T1S >= 3 的记录，而不是第一个输出中的其他记录。有什么办法可以做到这一点？

Answer 1

试试这个：

db.collection.find({
  "Game.T1S": {
    $gte: "2"
  }
}, {
  "team": 1,
  "Game.$": 1
})

你可以see it working here

想法是使用查找 projection 和 $ projection operator

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