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Group query upon nested object in MongoDB?
For this, use dot notation along with $group in MongoDB. Let us create a collection with documents −
> 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")
}Display all documents from a collection with the help of find() method −
> db.demo617.find();
This will produce the following output −
{ "_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" } }The group query upon nested object in MongoDB −
> db.demo617.aggregate({ $group : {_id : "$clientDetails.Project", All : { $sum : 1 }} });This will produce the following output −
{ "_id" : "Online Hosiptal Management System", "All" : 1 }
{ "_id" : "Online Library Management System", "All" : 2 }
Updated on: 12-May-2020
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