Mongodb aggregate group by array elements - mongodb

Question

I have a mongodb document that contains customer id, status (active, deactivate) and date.
[
{
id:1,
date:ISODate('2022-12-01'),
status:'activate'
},
{
id:2,
date:ISODate('2022-12-01'),
status:'activate'
},
{
id:1,
date:ISODate('2022-12-02'),
status:'deactivate'
},
{
id:2,
date:ISODate('2022-12-21'),
status:'deactivate'
}
]
I need to get daywise customer status count.
I came up with below aggregation.
db.collection.aggregate([
{
$addFields: {
"day": {
"$dateToString": {
"format": "%Y-%m-%d",
"date": "$date"
}
}
}
},
{
$group: {
_id: "$day",
type: {
$push: "$status"
}
}
}
])
this way I can get status in a array. like below.
[
{
_id:"2022-12-01",
type:[
0:"activate",
1:"activate"
]
},
{
_id:"2022-12-02",
type:[
0:"deactivate"
]
},
{
_id:"2022-12-21",
type:[
0:"deactivate"
]
}
]
now it's working as intended. but I need the output like below.
[
{
_id:"2022-12-01",
type:{
"activate":2,
}
},
{
_id:"2022-12-02",
type:{
"deactivate":1
}
},
{
_id:"2022-12-21",
type:{
"deactivate":1
}
}
]
this table has around 100,000 documents and doing this programmatically will take about 10 seconds. that's why I'm searching a way to do this as a aggregation

Answer 1

One option is to group twice and then use $arrayToObject:
db.collection.aggregate([
{$group: {
_id: {day: "$date", status: "$status"},
count: {$sum: 1}
}},
{$group: {
_id: {$dateToString: {format: "%Y-%m-%d", date: "$_id.day"}},
data: {$push: {k: "$_id.status", v: "$count"}}
}},
{$project: {type: {$arrayToObject: "$data"}}}
])
See how it works on the playground example