unable to access date value after lookup in mongodb - mongodb

Question

Main Collection
{
"_id": ObjectID("5ea1a07bfd7e4965408a5171"),
"data": [],
"history_id": ObjectID("5e4e755b380054797d9db627"),
"sender_id": ObjectID("5e4e74eb380054797d9db623"),
"text": "Hi tester",
"date": 1587650683434
}
History collection
{
"_id": ObjectID("5ea1afd4f4151402efd234e3"),
"user_id": [
"5e4a8d2d3952132a08ae5764"
],
"dialog_id": ObjectID("5e4e755b380054797d9db627"),
"date": 1587549034211,
"__v": 1
}
const messages = await MainModal.aggregate([
{
$lookup: {
from: 'history',
localField: 'history_id',
foreignField: 'history_id',
as: 'History'
}
},
{ $unwind: '$History' },
{ "$match" : { date: {$gt: "History.date" } } }, // this is not working
])
I am getting value inside $history but enable to fetch matched record. I don't know why i read somewhere $gt does work on number my date is number too
when i set string instead "History.date" it does work but after putting this doesnot work
Basically my idea is not to display those value whose date are $lt from history collection and where user not in 5e4a8d2d3952132a08ae5764

Answer 1

You are mixing the query language with aggregation operators. In order to use $match to compare two fields from the same document, you will need to use $expr along with aggregation operators.
For that final match stage, use
{ "$match":{ "$expr":{ "$gt":[ "$date", "$History.date" ] } } }
Edit
Adding an additional comparison between other fields would need to use $and or $or, like:
{ "$match":{
"$expr":{
"$and":[
{"$gt":[ "$date", "$History.date" ] },
{"$not": {"$eq":[ "$sender_id", "$History.user_id" ]}}
]
}
}}
Playground