using mongo aggregation how to replace the fields names [duplicate] - mongodb

Question

I have large collection of documents which represent some kind of events. Collection contains events for different userId.
{
"_id" : ObjectId("57fd7d00e4b011cafdb90d22"),
"userId" : "123123123",
"userType" : "mobile",
"event_type" : "clicked_ok",
"country" : "US",
"timestamp" : ISODate("2016-10-12T00:00:00.308Z")
}
{
"_id" : ObjectId("57fd7d00e4b011cafdb90d22"),
"userId" : "123123123",
"userType" : "mobile",
"event_type" : "clicked_cancel",
"country" : "US",
"timestamp" : ISODate("2016-10-12T00:00:00.308Z")
}
At midnight I need to run aggregation for all documents for the previous day. Documents need to aggregated in the way so I could get number of different events for particular userId.
{
"userId" : "123123123",
"userType" : "mobile",
"country" : "US",
"clicked_ok" : 23,
"send_message" : 14,
"clicked_cancel" : 100,
"date" : "2016-11-24",
}
During aggregation I need to perform two things:
calculate number of events for particular userId
add "date" text fields with date
Any help is greatly appreciated! :)

Answer 1

you can do this with aggregation like this :
db.user.aggregate([
{
$match:{
$and:[
{
timestamp:{
$gte: ISODate("2016-10-12T00:00:00.000Z")
}
},
{
timestamp:{
$lt: ISODate("2016-10-13T00:00:00.000Z")
}
}
]
}
},
{
$group:{
_id:"$userId",
timestamp:{
$first:"$timestamp"
},
send_message:{
$sum:{
$cond:[
{
$eq:[
"$event_type",
"send_message"
]
},
1,
0
]
}
},
clicked_cancel:{
$sum:{
$cond:[
{
$eq:[
"$event_type",
"clicked_cancel"
]
},
1,
0
]
}
},
clicked_ok:{
$sum:{
$cond:[
{
$eq:[
"$event_type",
"clicked_ok"
]
},
1,
0
]
}
}
}
},
{
$project:{
date:{
$dateToString:{
format:"%Y-%m-%d",
date:"$timestamp"
}
},
userId:1,
clicked_cancel:1,
send_message:1,
clicked_ok:1
}
}
])
explanation:
keep only document for a specific day in $match stage
group doc by userId and count occurrences for each event in $group stage
finally format the timestamp field into yyyy_MM-dd format in $project stage
for the data you provided, this will output
{
"_id":"123123123",
"send_message":0,
"clicked_cancel":1,
"clicked_ok":1,
"date":"2016-10-12"
}

Answer 2

Check the following query
db.sandbox.aggregate([{
$group: {
_id: {
userId: "$userId",
date: {
$dateToString: { format: "%Y-%m-%d", date: "$timestamp" }}
},
send_message: {
$sum: {
$cond: { if: { $eq: ["$event_type", "send_message"] }, then: 1, else: 0 } }
},
clicked_cancel: {
$sum: {
$cond: { if: { $eq: ["$event_type", "clicked_cancel"] }, then: 1, else: 0 }
}
},
clicked_ok: {
$sum: {
$cond: { if: { $eq: ["$event_type", "clicked_ok"] }, then: 1, else: 0 }
}
}
}
}])