how to use $groupby and transform distinct value mongodb - mongodb

Question

How to transform the data using $if $else groupby condition MongoDB?
This playground should return two object who belongs to text with "tester 2" and "tester 3" also if I have multiple object in history collection it should also check with last object not will all object how it is possible
So condition should say if history's date is $gt then main collection should return nothing else return the matched criteria data.
db.main.aggregate([
{
$lookup: {
from: "history",
localField: "history_id",
foreignField: "history_id",
as: "History"
}
},
{
$unwind: "$History"
},
{
"$match": {
$expr: {
$cond: {
if: {
$eq: [
"5e4e74eb380054797d9db623",
"$History.user_id"
]
},
then: {
$and: [
{
$gt: [
"$date",
"$History.date"
]
},
{
$eq: [
"5e4e74eb380054797d9db623",
"$History.user_id"
]
}
]
},
else: {}
}
}
}
}
])
MongoPlayground

Answer 1

If I understand you correctly, it is what you are trying to do:
db.main.aggregate([
{
$lookup: {
from: "history",
let: {
main_history_id: "$history_id",
main_user_id: { $toString: "$sender_id" }
},
pipeline: [
{
$match: {
$expr: {
$and: [
{
$eq: [
"$history_id",
"$$main_history_id"
]
},
{
$eq: [
"$user_id",
"$$main_user_id"
]
}
]
}
}
}
],
as: "History"
}
},
{
$unwind: {
path: "$History",
preserveNullAndEmptyArrays: true
}
},
{
$sort: {
_id: 1,
"History.history_id": 1,
"History.date": 1
}
},
{
$group: {
_id: "$_id",
data: { $last: "$$ROOT" },
History: { $last: "$History" }
}
},
{
$replaceRoot: {
newRoot: {
$mergeObjects: [
"$data",
{ History: "$History" }
]
}
}
},
{
"$match": {
$expr: {
$or: [
{
$eq: [
{ $type: "$History.date" },
"missing"
]
},
{
$ne: [
"5e4e74eb380054797d9db623",
"$History.user_id"
]
},
{
$and: [
{
$eq: [
"5e4e74eb380054797d9db623",
"$History.user_id"
]
},
{
$gte: [
"$date",
"$History.date"
]
}
]
}
]
}
}
}
])
MongoPlayground