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 } } ] } }