用MongoDB对嵌入式文档数组进行过滤查询
为此，请在MongoDB中使用aggregate()。让我们创建一个包含文档的集合-
> db.demo736.insertOne(
... {
... "_id": "101",
... "details1": [
... {
... "details2": [
... {
... "details3": {
... "Name": "John"
... }
... }
... ]
... }
... ]
... }
... );
{ "acknowledged" : true, "insertedId" : "101" }
> db.demo736.insertOne(
... {
... "_id": "102",
... "details1": [
... {
... "details2": [
... {
... "details3": {
... "Name": "Robert"
... }
... }
... ]
... }
... ]
... }
... );
{ "acknowledged" : true, "insertedId" : "102" }在find()方法的帮助下显示集合中的所有文档-
> db.demo736.find();
这将产生以下输出-
{ "_id" : "101", "details1" : [ { "details2" : [ { "details3" : { "Name" : "John" } } ] } ] }
{ "_id" : "102", "details1" : [ { "details2" : [ { "details3" : { "Name" : "Robert" } } ] } ] }以下是在MongoDB中过滤嵌入式文档数组（3个级别）的查询-
> db.demo736.aggregate([
... {
... "$unwind": "$details1"
... },
... {
... "$unwind": "$details1.details2"
... },
... {
... "$match": {
... "details1.details2.details3.Name": "Robert"
... }
... },
... {
... $project: {
... _id: 0,
... Name: "$details1.details2.details3",
... }
... }
... ])这将产生以下输出-
{ "Name" : { "Name" : "Robert" } }