Problem with grouping with conditional sum in MongoDB - mongodb

Question

I'm trying to partition the some documents according to the previous 6 months and then compute the conditional sum of certain fields that satisfy certain conditions. The problem I'm having is that I can't see a way to do this in a less verbose manner. I'm basically looking for a way to iterate over the previous 6 months then get the conditional sum of the field.
Below is what I've done :
[
{
'$facet': {
'JanuaryTotal': [
{
'$match': {
'bookingDate': {
'$gte': ISODate('2020-01-01T00:00:00.000Z'),
'$lt': ISODate('2020-02-01T00:00:00.000Z')
}
}
}, {
'$project': {
'_id': 0,
'approved': {
'$cond': [
{
'$eq': [
'$approvalStatus', 'approved'
]
}, '$cost', 0
]
},
'pending': {
'$cond': [
{
'$eq': [
'$approvalStatus', 'pending'
]
}, '$cost', 0
]
},
'denied': {
'$cond': [
{
'$eq': [
'$approvalStatus', 'denied'
]
}, '$cost', 0
]
}
}
}, {
'$group': {
'_id': null,
'sumApproved': {
'$sum': '$approved'
},
'summPending': {
'$sum': '$pending'
},
'sumDenied': {
'$sum': '$denied'
}
}
}
]
}
}
]
Sample Document :
{
"_id":"5e45b621da68610f13aa0cba",
"type":"international",
"booking":"2222222",
"bookingId":"22222222",
"chatId":"Q22222222",
"approvalStatus":"approved",
"pax": "2",
"cost":"222",
"charged":"222",
"chargedGCT": "222.22",
"commRate": "2",
"commUSD":"22.22",
"commJMD":"2222.02",
"bookingDate": ISODate('2020-02-01T18:00:55.000+00:00),
"tourDate": ISODate('2020-02-03T18:00:55.000+00:00'),
"clientName":"test",
"agent":{
"agentName":"test",
"agentId":{
"$numberInt":"1"
}
}
}
Is there a way to do iterate through the previous 6 months in a more succinct manner?

Answer 1

You can try below query :
db.collection.aggregate([
/** Match docs fall under previous 6 months */
{
$match: {
'bookingDate': {
'$gte': ISODate('2019-09-01T00:00:00.000Z'),
'$lt': ISODate('2020-02-01T00:00:00.000Z')
}
}
},
/** This project is to reduce document size by opting lesser fields - Optional if dataset size is less */
{ $project: { _id: 0, cost: { $toInt: '$cost' }, approvalStatus: 1, bookingDate: 1 } },
/** Grouping on month & approvalStatus + cost */
{ $group: { _id: { month: { $month: "$bookingDate" }, approvalStatus: '$approvalStatus' }, cost: { $sum: '$cost' } } },
/** Grouping on month pushing { approvalStatus + cost } objects to data field */
{ $group: { _id: '$_id.month', data: { $push: { approvalStatus: '$_id.approvalStatus', cost: '$cost' } } } },
/** converting month numbers to string Ex.:- 1 as 'Jan' - Optional if no need to be converted */
{
$project: {
_id: 0, data: 1, month: {
$let: {
vars: {
monthsInString: ['', 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'July', 'Aug', 'Sept', 'Oct', 'Nov', 'Dec']
},
in: {
$arrayElemAt: ['$$monthsInString', '$_id']
}
}
}
}
}
])
Test : MongoDB-Playground

Answer 2

db.collection.aggregate([
{
$match: {
bookingDate: {
$gte: ISODate("2019-09-01T00:00:00.000Z"),
$lte: ISODate("2020-02-01T00:00:00.000Z")
}
}
},
{
$group: {
_id: {
$month: "$bookingDate"
},
sumApproved: {
$sum: { $cond: [ { $eq: ['$approvalStatus','approved']} , { $toDouble: "$cost" }, 0] }
},
sumPending: {
$sum: { $cond: [ { $eq: ['$approvalStatus','pending']} , { $toDouble: "$cost" }, 0] }
},
sumDenied: {
$sum: { $cond: [ { $eq: ['$approvalStatus','denied']} , { $toDouble: "$cost" }, 0 ] }
}
}
},
{
$project: {
_id: 0,
monthNumber: "$_id",
sumApproved: "$sumApproved",
sumPending: "$sumPending",
sumDenied: "$sumDenied"
}
}
]);
https://mongoplayground.net/p/iTyRuiQc8EI