Group Query บน Nested Object ใน MongoDB

การ Group Query บน Nested Object

สำหรับการนี้ ให้ใช้ Dot Notation ร่วมกับ $group ใน MongoDB

สร้าง Collection พร้อมข้อมูล

> db.demo617.insertOne(
...     {
...         "clientDetails": {
...             "Name": "Chris",
...             "Age":32,
...             "Project":"Online Library Management System"
...         }
...     }
... );
{ "acknowledged" : true, "insertedId" : ObjectId("5e99d2b86c954c74be91e69b") }
> db.demo617.insertOne(
...     {
...         "clientDetails": {
...             "Name": "David",
...             "Age":34,
...             "Project":"Online Hospital Management System"
...         }
...     }
... );
{ "acknowledged" : true, "insertedId" : ObjectId("5e99d2b86c954c74be91e69c") }
> db.demo617.insertOne(
...     {
...         "clientDetails": {
...             "Name": "David",
...             "Age":34,
...             "Project":"Online Library Management System"
...         }
...     }
... );
{ "acknowledged" : true, "insertedId" : ObjectId("5e99d2b96c954c74be91e69d") }

แสดงเอกสารทั้งหมด

> db.demo617.find();

ผลลัพธ์:

{ "_id" : ObjectId("5e99d2b86c954c74be91e69b"), "clientDetails" : { "Name" : "Chris", "Age" : 32, "Project" : "Online Library Management System" } }
{ "_id" : ObjectId("5e99d2b86c954c74be91e69c"), "clientDetails" : { "Name" : "David", "Age" : 34, "Project" : "Online Hospital Management System" } }
{ "_id" : ObjectId("5e99d2b96c954c74be91e69d"), "clientDetails" : { "Name" : "David", "Age" : 34, "Project" : "Online Library Management System" } }

คิวรี Group บน Nested Object

> db.demo617.aggregate({ $group : {_id : "$clientDetails.Project", All : { $sum : 1 }} });

ผลลัพธ์:

{ "_id" : "Online Hosiptal Management System", "All" : 1 }
{ "_id" : "Online Library Management System", "All" : 2 }