Group into group and count using aggregation framework in MongoDB - mongodb

Question

I am trying to group data within group with the count.
{
"_id" : ObjectId("59899846b5f5670840040b0b"),
"client_id" : "merlin",
"scope" : "eee",
"user_id" : "u",
"user_directory" : "kmdkcn",
"createdAt" : ISODate("2017-08-08T10:53:58.816Z"),
"open_url" : null,
"__v" : 0
}
{
"_id" : ObjectId("59899849b5f5670840040b0c"),
"client_id" : "merlin",
"scope" : "eee",
"user_id" : "u",
"user_directory" : "kmdkcn",
"createdAt" : ISODate("2017-08-08T10:54:01.908Z"),
"open_url" : null,
"__v" : 0
}
{
"_id" : ObjectId("5989984db5f5670840040b0d"),
"client_id" : "merlin",
"scope" : "eee",
"user_id" : "y",
"user_directory" : "kmdkcn",
"createdAt" : ISODate("2017-08-08T10:54:05.280Z"),
"open_url" : null,
"__v" : 0
}
{
"_id" : ObjectId("5989adb2d699bd211caa07ad"),
"client_id" : "symphony",
"scope" : "eee",
"user_id" : "q",
"user_directory" : "kmdkcn",
"createdAt" : ISODate("2017-08-08T12:25:22.518Z"),
"open_url" : null,
"__v" : 0
}
{
"_id" : ObjectId("5989adb8d699bd211caa07ae"),
"client_id" : "symphony",
"scope" : "eee",
"user_id" : "w",
"user_directory" : "kmdkcn",
"createdAt" : ISODate("2017-08-08T12:25:28.954Z"),
"open_url" : null,
"__v" : 0
}
{
"_id" : ObjectId("5989adbcd699bd211caa07af"),
"client_id" : "symphony",
"scope" : "eee",
"user_id" : "q",
"user_directory" : "kmdkcn",
"createdAt" : ISODate("2017-08-08T12:25:32.753Z"),
"open_url" : null,
"__v" : 0
}
{
"_id" : ObjectId("5989adc0d699bd211caa07b0"),
"client_id" : "symphony",
"scope" : "eee",
"user_id" : "r",
"user_directory" : "kmdkcn",
"createdAt" : ISODate("2017-08-08T12:25:36.176Z"),
"open_url" : null,
"__v" : 0
}
What i want is to group data on the basis of client_id and further on the basis of user_id to get the count of documents.
i have tried this:-
Logger.aggregate([
{ "$group": {
"_id": {client: "$client_id"},
"count": { "$sum": 1 }
}}
])
I am getting:-
client: merlin
count: 3,
client: symphony,
count: 4
But how to group this on the basis of user_id.
I want the final output would be:-
client: merlin,
count: 2,
client: symphony,
count: 3

Answer 1

Here is the query.
db.collection.aggregate([
{ "$group": {
"_id": {client: "$client_id" },
"clientIdCount": { "$sum": 1 },
"userids" : {"$addToSet" : "$user_id"}
}
},
{ "$project" : {"_id.client" : 1, "clientIdCount" : 1, numberOfUsers : {$size : "$userids"} }
}
]);
Output:-
If you don't want clientIdCount in the output, just change the value from 1 to 0 present next to clientIdCount.
/* 1 */
{
"_id" : {
"client" : "symphony"
},
"clientIdCount" : 4,
"numberOfUsers" : 3
}
/* 2 */
{
"_id" : {
"client" : "merlin"
},
"clientIdCount" : 3,
"numberOfUsers" : 2
}

Answer 2

If I understood your question correctly this your db query
db.Logger.aggregate([
{
$group : {
_id : "$client_id", user : { $push: "$user_id" },
count: { $sum: 1 }
}
}
])