MongoDB-查询嵌入式文档

要查询MongoDB中的嵌入式文档，请使用aggregate()。让我们创建一个包含文档的集合-

> db.demo705.insertOne( ... { ... _id:101, ... "Information": ... [ ... { ... "StudentName":"Chris", ... "StudentAge":21 ... }, ... { ... "StudentName":"David", ... "StudentAge":23 ... }, ... { ... "StudentName":"Bob", ... "StudentAge":20 ... } ... ] ... } ... ); { "acknowledged" : true, "insertedId" : 101 }

在find()方法的帮助下显示集合中的所有文档-

> db.demo705.find();

这将产生以下输出-

{ "_id" : 101, "Information" : [ { "StudentName" : "Chris", "StudentAge" : 21 }, { "StudentName" : "David", "StudentAge" : 23 }, { "StudentName" : "Bob", "StudentAge" : 20 } ] }

以下是如何在MongoDB中查询嵌入式文档-

> db.demo705.aggregate( ... { $unwind: $Information }, ... { $match: {Information.StudentAge: {$gte: 21}}}, ... { $project: {Information: 1}} ... )

这将产生以下输出-

{ "_id" : 101, "Information" : { "StudentName" : "Chris", "StudentAge" : 21 } } { "_id" : 101, "Information" : { "StudentName" : "David", "StudentAge" : 23 } }