$lookup with condition in mongoose - node.js

Question

I have 2 schemas, this is parent collection schema:
const TimesheetSchema = Schema({
managersComment: {
type: String,
},
weekNum: {
type: Number,
},
year: {
type: Number,
},
user: { type: Schema.Types.ObjectId, ref: userModel },
status: {
type: String,
enum: ["Saved", "Submitted", "Approved", "Rejected"],
},
data: [{ type: Schema.Types.ObjectId, ref: TimesheetIndividualData }]
});
This is child collection schema
const TimesheetDataSchema = new Schema(
{
workingDate: {
type: Date,
},
dayVal: {
type: Number,
},
user: { type: Schema.Types.ObjectId, ref: userModel },
parentId: { type: String }
},
{ timestamps: true }
);
In TimesheetDataSchema parentId is basically the _id from TimesheetSchema.
Now i need to run a query which return docs from TimesheetDataSchema, but only the docs in which parentId(ObjectId) of TimesheetSchema has status Approved.
I am trying to do $lookup, but currently no success. Please help.
EDIT: Based upon #ashh suggestion tried this: but getting empty array.
const result = await TimesheetIndividualData.aggregate([
{
"$lookup": {
"from": "timesheetModel",
"let": { "parentId": "$parentId" },
"pipeline": [
{ "$match": { "status": "Approved", "$expr": { "$eq": ["$weekNum", "$parentId"] } } },
],
"as": "timesheet"
}
},
{ "$match": { "timesheet": { "$ne": [] } } }
])

Answer 1

You can use below aggregation
const result = await db.TimesheetDataSchema.aggregate([
{ "$lookup": {
"from": "TimesheetSchema",
"let": { "parentId": "$parentId" },
"pipeline": [
{ "$match": { "status": "approved", "$expr": { "$eq": ["$_id", "$$parentId"] }}},
],
"as": "timesheet"
}},
{ "$match": { "timesheet": { "$ne": [] }} }
])
But I would prefer two queries for better performance here
const timesheets = (await db.TimesheetSchema.find({ status: "approved" }, { _id: 1 })).map(({ _id }) => _id)
const result = await db.TimesheetDataSchema.find({ parentId: { $in: timesheets } })