How to merge/join mongodb aggregate? - mongodb

Question

Given this dataset:
db.calls.insert([{
"agent": 2,
"isFromOutside": true,
"duration": 304
}, {
"agent": 1,
"isFromOutside": false,
"duration": 811
}, {
"agent": 0,
"isFromOutside": true,
"duration": 753
}, {
"agent": 1,
"isFromOutside": false,
"duration": 593
}, {
"agent": 3,
"isFromOutside": true,
"duration": 263
}, {
"agent": 0,
"isFromOutside": true,
"duration": 995
}, {
"agent": 0,
"isFromOutside": false,
"duration": 210
}, {
"agent": 1,
"isFromOutside": false,
"duration": 737
}, {
"agent": 2,
"isFromOutside": false,
"duration": 170
}, {
"agent": 0,
"isFromOutside": false,
"duration": 487
}])
I have two aggregate queries that give the total duration for each agent and the count of outgoing calls for each client:
get outGoingCalls table:
db.calls.aggregate([
{ $match: { duration :{ $gt: 0 }, isFromOutside: false } },
{ $group: { _id: "$agent", outGoingCalls: { $sum: 1 } } },
{ $sort: { outGoingCalls: -1 } }
])
get totalDuration table:
db.calls.aggregate([
{ $group: { _id: "$agent", totalDuration: { $sum: "$duration" } } },
{ $sort: {totalDuration: -1 } }
])
How to merge/join these tables (or do only one aggregation) to have something like this:
[
{_id: 0, totalDuration: ..., outGoingCalls: ...},
{_id: 1, totalDuration: ..., outGoingCalls: ...},
{_id: 2, totalDuration: ..., outGoingCalls: ...},
...
]

Answer 1

Try the following aggregation framework:
db.calls.aggregate([
{
"$group": {
"_id": "$agent",
"outGoingCalls": {
"$sum": {
"$cond": [
{
"$and": [
{"$gt": ["$duration", 0 ]},
{"$eq": ["$isFromOutside", false ]}
]
},
1,
0
]
}
},
"totalDuration": { "$sum": "$duration" }
}
},
{
"$sort": {
"totalDuration": -1,
"outGoingCalls": -1
}
}
])
Output:
/* 0 */
{
"result" : [
{
"_id" : 0,
"outGoingCalls" : 2,
"totalDuration" : 2445
},
{
"_id" : 1,
"outGoingCalls" : 3,
"totalDuration" : 2141
},
{
"_id" : 2,
"outGoingCalls" : 1,
"totalDuration" : 474
},
{
"_id" : 3,
"outGoingCalls" : 0,
"totalDuration" : 263
}
],
"ok" : 1
}