MongoDB 子文档使用 NestJs 获取具有文档计数的不同文档答案

【问题标题】：MongoDB sub Documents fetch as different documents with document count using NestJsMongoDB 子文档使用 NestJs 获取具有文档计数的不同文档
【发布时间】：2021-03-19 16:52:09
【问题描述】：

我有这样的 MongoDb 文档，所以我需要编写一个查询 => {"enrolments.date" : { $gte:"2020-12-01T00:00:00.000Z"} }，但我需要将这些文档作为单独的文档，在本例中，文档计数二，那我该怎么办？

    "_id" : "10000",
    "Class" : "A",
    "enrolments" : [ 
        {"id" : "10000-1","name" : "Test1","month":"2020-11","date":"2020-12-08T10:37:00.000Z"},
        {"id" : "10000-2","name" : "Test2","month":"2020-12","date":"2020-12-07T10:37:00.000Z"},
        {"id" : "10000-3","name" : "Test3","month":"2020-12","date":"2020-11-16T10:37:00.000Z"}
    ]
}

Output =>

    "_id":"10000",
    "Class":"A",
    "enrolments":[ 
        {"id":"10000-1","name":"Test1","month":"2020-11","date":"2020-12-08T10:37:00.000Z"}
    ]
},{
    "_id" : "10000",
    "Class" : "A",
    "enrolments" : [
        {"id" : "10000-2","name" : "Test2","month":"2020-12","date":"2020-12-07T10:37:00.000Z"}
    ]
}

like this

【问题讨论】：

标签： mongodb mongoose nestjs

【解决方案1】：

您正在寻找的是$unwind。所以你应该这样写：

db.collection.aggregate( [ 
{ 
     $unwind : "$enrolments" 
},
{
     $match : { "$enrolments.date" : { $gte:"2020-12-01T00:00:00.000Z"} }
} 
] )

【讨论】：