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Get the count of a specific value in MongoDB
To get the count of a specific value in MongoDB, use aggregate(). Let us create a collection with documents −
> db.demo210.insertOne(
... {
... details: [
... {
... ClientName: "Robert"
... },
... {
...
... lientName: "John Doe"
... },
... {
...
... ClientName: "Robert"
... },
... {
...
... ClientName: "Robert"
... },
... {
...
... ClientName: "David Miller"
... }
... ]
... }
...);
{
"acknowledged" : true,
"insertedId" : ObjectId("5e3d99ab03d395bdc21346f9")
}Display all documents from a collection with the help of find() method −
> db.demo210.find();
This will produce the following output −
{ "_id" : ObjectId("5e3d99ab03d395bdc21346f9"), "details" : [ { "ClientName" : "Robert" }, { "ClientName" : "John Doe" }, { "ClientName" : "Robert" }, { "ClientName" : "Robert" }, { "ClientName" : "David Miller" } ] }Following is the query to get the count of a specific value −
> db.demo210.aggregate([
... { "$match" : { "details.ClientName" : "Robert" } },
... { "$unwind" : "$details" },
... { "$match" : { "details.ClientName" : "Robert" } },
... { "$group" : { "_id" : "$_id", "Size" : { "$sum" : 1 } } },
... { "$match" : { "Size" : { "$gte" : 2 } } }
...]);This will produce the following output −
{ "_id" : ObjectId("5e3d99ab03d395bdc21346f9"), "Size" : 3 }
Updated on: 27-Mar-2020
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