让我们创建一个包含文档的集合-
> db.demo411.aggregate(
... [
... {$project : {
... _id : 0,
... Information : {$map : {input : "$Information", as : "out", in : ["$$out.Name1", "$$out.Name2"]}}
... }
... }
... ]
... )
{ "Information" : [ [ "Chris", "David" ], [ "John", "John" ] ] }
> db.demo412.insertOne(
... {
... "Information1" : [
... {
... "Information2" : [
... "John",
... "David"
... ]
... },
... {
... "Information2" : [
... "Mike"
... ]
... }
... ]
... }
... );
{
"acknowledged" : true,
"insertedId" : ObjectId("5e70f38b15dc524f70227683")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo412.find();
这将产生以下输出-
{ "_id" : ObjectId("5e70f38b15dc524f70227683"), "Information1" : [ { "Information2" : [ "John", "David" ] }, { "Information2" : [ "Mike" ] } ] }以下是更新MongoDB中嵌套在对象数组中的字符串数组的查询-
> db.demo412.updateMany(
... { _id: ObjectId("5e70f38b15dc524f70227683") },
... { $pull : {'Information1.$[].Information2' : "Mike" } }
... );
{ "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 }在find()方法的帮助下显示集合中的所有文档-
> db.demo412.find();
这将产生以下输出-
{ "_id" : ObjectId("5e70f38b15dc524f70227683"), "Information1" : [ { "Information2" : [ "John", "David" ] }, { "Information2" : [ ] } ] }