MongoDB中如何过滤多个子文档
要过滤MongoDB中的多个子文档，请使用aggregate()。让我们创建一个包含文档的集合-
> db.demo200.insertOne(
... {
... "Id":"101",
... "details1":[
... {
... "isActive":true,
... "SubjectName":"MySQL"
... },{
... "isActive":false,
... "SubjectName":"Java"
... }
... ],
... "details2":[
... {
... "isActive":false,
... "Name":"David"
... },{
... "isActive":true,
... "Name":"Mike"
... }
... ]
... }
...);
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3c374f03d395bdc21346e4")
}在find()方法的帮助下显示集合中的所有文档-
> db.demo200.find();
这将产生以下输出-
{
"_id" : ObjectId("5e3c374f03d395bdc21346e4"), "Id" : "101", "details1" : [
{ "isActive" : true, "SubjectName" : "MySQL" },
{ "isActive" : false, "SubjectName" : "Java" } ], "details2" : [ { "isActive" : false, "Name" : "David" },
{ "isActive" : true, "Name" : "Mike" }
]
}以下是过滤多个子文档的查询-
> var out= [
... {
... "$match": {
... "Id": "101",
... "details1.isActive": true,
... "details2.isActive": true
... }
... },
... { "$unwind": "$details1" },
... { "$unwind": "$details2" },
... {
... "$match": {
... "details1.isActive": true,
... "details2.isActive": true
... }
... },
... {
... "$group": {
... "_id": {
... "_id": "$_id",
... "Id": "$Id"
... },
... "details2": { "$addToSet" : "$details2" },
... "details1": { "$addToSet" : "$details1" }
... }
... },
... {
... "$project": {
... "_id": 0,
... "Id": "$_id.Id",
... "details2": 1,
... "details1": 1
... }
... }
...]
>
> db.demo200.aggregate(out)这将产生以下输出-
{ "details2" : [ { "isActive" : true, "Name" : "Mike" } ], "details1" : [ { "isActive" : true, "SubjectName" : "MySQL" } ], "Id" : "101" }