Mongo DB aggregation query to get an attribute based on another array of objects - mongodb

Question

I am trying to
get all the ids for which the period.startDate > sysdate
get all the ids for which the period.endDate < sysdate
from the JSON.
[
{
"id": 1,
"period":
[
{
"startDate": "2020-05-05",
"endDate": "2020-05-06"
},
{
"startDate": "2020-06-05",
"endDate": "2020-06-06"
}
]
},
{
"id": 2,
"period":
[
{
"startDate": "2024-07-05",
"endDate": "2024-07-06"
},
{
"startDate": "2024-08-05",
"endDate": "2024-08-06"
}
]
}
]
I have tried to go far as below aggregation:
[{
$project: {
_id: 0,
sId: '$id',
period: 1
} }, {
$unwind: {
path: '$period',
includeArrayIndex: 'index'
} }, {
$group: {
_id: '$sId',
minDate: {
$min: '$periods.startDate'
}
} }, {
$project: {
storeId: '$_id',
_id: 0,
minDated: {
$dateFromString: {
dateString: '$minDate'
}
},
today: ISODate('2022-08-03T11:37:03.954Z')
} }]

Answer 1

One option is using $reduce and $group:
db.collection.aggregate([
{$project: {
_id: 0,
id: 1,
minDate: {
$dateFromString: {
dateString: {
$reduce: {
input: "$period",
initialValue: {$first: "$period.startDate"},
in: {$min: ["$$value", "$$this.startDate"]}
}
}
}
},
maxDate: {
$dateFromString: {
dateString: {
$reduce: {
input: "$period",
initialValue: {$first: "$period.endDate"},
in: {$max: ["$$value", "$$this.startDate"]}
}
}
}
}
}
},
{$group: {
_id: 0,
startDateLargerIds: {
$push: {
$cond: [{$gt: ["$minDate", ISODate("2022-08-03T11:37:03.954Z")]},
"$id", "$$REMOVE"]}
},
endDateSmallerIds: {
$push: {
$cond: [{$lt: ["$maxDate", ISODate("2022-08-03T11:37:03.954Z")]},
"$id", "$$REMOVE"]}
}
}
},
{$unset: "_id"}
])
See how it works on the playground example