how can i get sum of all amounts requested - mongoDB - node.js

Question

I am working on an HRM project using MERN stack I have a medical expense section in which employees can request expense coverage (limit = 6000), how can I sum all requested amounts by employee and check if each employee is exceeding the limit before requesting here is my code:-
router.post("/", async (req, res) => {
// check if employee has pending request
let medicalExpenseRequest = await MedicalExpenseRequest.findOne({
"employee._id": req.body.employeeId,
"medicalExpense._id": req.body.medicalExpenseId,
status: "Pending",
});
if (medicalExpenseRequest)
return res
.status(400)
.send("Oops there is pending medical request for this employee!");
// this blocks the employee to request more than the limit at once // medicalexpense.allowed == 6000
if (req.body.amount > medicalExpense.allowedAmount)
return res
.status(400)
.send(
`Sorry can't request more than ${medicalExpense.allowedAmount} ETB`
);
// keep track of each employee request
//I want to check if the sum of all amounts requested by employee is greater than the limit and block if it is true
let taken;
const coveredExpense = await MedicalExpenseRequest.aggregate([
// { $match: { _id: { $eq: req.body.employeeId } } },
{
$group: {
_id: "$employee._id",
totalTaken: { $sum: "$amount" },
},
},
]);
// process the request successfully
});
NB: I tried MongoDB aggregates but I could not able to achieve the target

Answer 1

i figured out by my self what i did is to filter through coveredExpense and check if taken amount is greater than the allowed amount
coveredExpense.filter((expense) => {
taken = expense.totalTaken;
emp_id = expense._id;
});
if (
taken >= medicalExpense.allowedAmount &&
medicalRequesEmployee &&
medicalRequesEmployee.employee._id.equals(emp_id)
) {
return res.status(400).send("You have exceeded the limit");
}