使用NestJs将MongoDB子文档作为具有文档计数不同文档获取

Question

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"} }，但是我需要将这些文档作为单独的文档，在本例中，文档数为2，那么我该怎么做呢？

    "_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

Answer 1

你要找的是$unwind。所以你应该写这样的代码：

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