MongoDB中如何访问JSON数组的内部元素

要在MongoDB中访问JSON数组的内部元素，请使用点表示法。让我们创建一个包含文档的集合-

> db.demo687.insert({CountryName:US, ... info: ... { ... id:101, ... details: ... [ ... { ... Name:Chris, ... SubjectName:MongoDB, ... otherDetails:{ ... "Marks":58, ... Age:23 ... } ... } ... ] ... } ... } ... ) WriteResult({ "nInserted" : 1 }) > db.demo687.insert({CountryName:UK, ... info: ... { ... id:102, ... details: ... [ ... { ... Name:David, ... SubjectName:MySQL, ... otherDetails:{ ... "Marks":78, ... Age:21 ... } ... } ... ] ... } ... } ... ) WriteResult({ "nInserted" : 1 })

在find()方法的帮助下显示集合中的所有文档-

> db.demo687.find();

这将产生以下输出-

{ "_id" : ObjectId("5ea55658a7e81adc6a0b3962"), "CountryName" : "US", "info" : { "id" : 101, "details" : [ { "Name" : "Chris", "SubjectName" : "MongoDB", "otherDetails" : { "Marks" : 58, "Age" : 23 } } ] } } { "_id" : ObjectId("5ea55673a7e81adc6a0b3963"), "CountryName" : "UK", "info" : { "id" : 102, "details" : [ { "Name" : "David", "SubjectName" : "MySQL", "otherDetails" : { "Marks" : 78, "Age" : 21 } } ] } }

以下是访问JSON数组内部元素的查询-

> db.demo687.find({"info.details.otherDetails.Marks":58});

这将产生以下输出-

{ "_id" : ObjectId("5ea55658a7e81adc6a0b3962"), "CountryName" : "US", "info" : { "id" : 101, "details" : [ { "Name" : "Chris", "SubjectName" : "MongoDB", "otherDetails" : { "Marks" : 58, "Age" : 23 } } ] } }