MongoDB 中如何按子文档过滤子文档？
为此，将aggregate()与$unwind一起使用。让我们创建一个包含文档的集合-
> db.demo583.insert([
... {
... "details1" : [
... {
... "details2" : [
... {
... "isMarried" : true,
... "Name" : "Chris"
... },
... {
... "isMarried" : true,
... "Name" : "Bob"
... }
... ]
... },
... {
... "details2" : [
... {
... "isMarried" : false,
... "Name" : "Chris"
... },
... {
... "isMarried" : true,
... "Name" : "Mike"
... }
... ]
... }
... ]
... }
... ]);
BulkWriteResult({
"writeErrors" : [ ],
"writeConcernErrors" : [ ],
"nInserted" : 1,
"nUpserted" : 0,
"nMatched" : 0,
"nModified" : 0,
"nRemoved" : 0,
"upserted" : [ ]
})在find()方法的帮助下显示集合中的所有文档-
> db.demo583.find();
这将产生以下输出-
{ "_id" : ObjectId("5e91d3c4fd2d90c177b5bcc1"), "details1" : [
{ "details2" : [
{ "isMarried" : true, "Name" : "Chris" },
{ "isMarried" : true, "Name" : "Bob" }
] },
{ "details2" : [
{ "isMarried" : false, "Name" : "Chris" },
{ "isMarried" : true, "Name" : "Mike" }
] }
] }以下是按子文档过滤子文档的查询-
> var q= [
... {
... "$match": {
... "details1.details2.isMarried": true,
... "details1.details2.Name": "Chris"
... }
... },
... {
... "$unwind": "$details1"
... },
... {
... "$unwind": "$details1.details2"
... },
... {
... "$match": {
... "details1.details2.isMarried": true,
... "details1.details2.Name": "Chris"
... }
... }
... ];
> db.demo583.aggregate(q).pretty();这将产生以下输出-
{
"_id" : ObjectId("5e91d3c4fd2d90c177b5bcc1"),
"details1" : {
"details2" : {
"isMarried" : true,
"Name" : "Chris"
}
}
}