What aggregate should I do in MongoDB? - mongodb

Question

I have a collection that contains data as below sample
{ "_id" : "...." , "team" : [ {"name" : "A", "state" : "Active"} , {"name" : "B", "state" : "Deactive", {"name" : "C", "state" : "Unknown"} } ]},
{ "_id" : "...." , "team" : [ {"name" : "A", "state" : "Unknown"} , {"name" : "B", "state" : "Deactive", {"name" : "C", "state" : "Unknown"} } ]},
{ "_id" : "...." , "team" : [ {"name" : "A", "state" : "Active"} , {"name" : "B", "state" : "Deactive", {"name" : "C", "state" : "Unknown"} } ]}
I filter by "team.name" and want to know what is state and count each state as below sample result
{ "name" : "A", "Active" : 2, "Unknown" : 1},
{ "name" : "B", "Deactive" : 3},
{ "name" : "C", "Unknown" : 3"}
Is it possible to use only aggregate function of MongoDB without any codes?

Answer 1

Is it possible to use only aggregate function of MongoDB without any
codes?
Yes
TL;DR unwind and group
db.getCollection('foo').aggregate([
{$unwind:"$team"},
{
$group: {
_id: "$team.name",
"Active": {$sum: {$cond:[{$eq:["$team.state","Active"]},1,0]}},
"Deactive": {$sum: {$cond:[{$eq:["$team.state","Deactive"]},1,0]}},
"Unknown": {$sum: {$cond:[{$eq:["$team.state","Unknown"]},1,0]}}
}
},
{$project: {_id:0, name:"$_id", Active:1, Deactive:1, Unknown:1}},
{$sort: {name:1}}
])
Output for your sample:
[
{ "name" : "A", "Active" : 2, "Deactive" : 0, "Unknown" : 1 },
{ "name" : "B", "Active" : 0, "Deactive" : 3, "Unknown" : 0 },
{ "name" : "C", "Active" : 0, "Deactive" : 0, "Unknown" : 3 }
]