Unhandled promise rejection mongoose aggregate - node.js

Question

I know there are multiple posts handling similar types of issue but none of them seems to work for me.
In my application, I need to fetch the graphical data for the vertical bar chart from my database. The filtration is based on the two status types and the updatedAt field. The data will be plotted for each month of the year.
I tried two approaches to the same:
First:
exports.leads_based_on_status = async (req, res) => {
const { userId } = req.user;
const fetchMonths = getMonths();
try {
const fetch_leads_new = await fetchMonths.map(async (month) => {
return Lead.aggregate([
{
$match: {
userId: mongoose.Types.ObjectId(userId),
},
},
{
$unwind: "$leads",
},
{
$match: {
$and: [
{ updatedAt: { $gt: month._start, $lt: month._end } },
{ "leads.status": "New" },
],
},
},
]);
});
const fetch_leads_pending = await fetchMonths.map(async (month) => {
return Lead.aggregate([
{
$match: {
userId: mongoose.Types.ObjectId(userId),
},
},
{
$unwind: "$leads",
},
{
$match: {
$and: [
{ updatedAt: { $gt: month._start, $lt: month._end } },
{ "leads.status": "Pending" },
],
},
},
]);
});
Promise.all([fetch_leads_new, fetch_leads_pending]).then(
(resultnew, resultpending) => {
console.log("show result new", resultnew);
console.log("show result pending", resultpending);
//both these results in Promise <pending>
}
);
const leads_status_statics = [
{
New: fetch_leads_new,
},
{
Pending: fetch_leads_pending,
},
];
res.status(200).json({ message: "Graphical Data", leads_status_statics });
} catch (error) {
console.log(error) || res.status(500).json({ error });
}
};
Second:
exports.leads_based_on_status = async (req, res) => {
const { userId } = req.user;
const fetchMonths = getMonths();
try {
fetchMonths.map(async (month) => {
const fetch_leads_new = await Lead.aggregate([
{
$match: {
userId: mongoose.Types.ObjectId(userId),
},
},
{
$unwind: "$leads",
},
{
$match: {
$and: [
{ updatedAt: { $gt: month._start, $lt: month._end } },
{ "leads.status": "New" },
],
},
},
]);
const fetch_leads_pending = await Lead.aggregate([
{
$match: {
userId: mongoose.Types.ObjectId(userId),
},
},
{
$unwind: "$leads",
},
{
$match: {
$and: [
{ updatedAt: { $gt: month._start, $lt: month._end } },
{ "leads.status": "New" },
],
},
},
]);
const leads_status_statics = [
{
New: fetch_leads_new,
},
{
Pending: fetch_leads_pending,
},
];
res.status(200).json({ message: "Graphical Data", leads_status_statics });
//de:16484) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
});
} catch (error) {
console.log(error) || res.status(500).json({ error });
}
};
But none of them is able to help me resolve my issue. The first approach keeps returning Promise <Pending>, while the second approach returns Cannot set headers after they are sent to the client
at ServerResponse.setHeader (_http_outgoing.js:467:11)
Any help to rectify the problem is appreciated :)

Answer 1

Regarding your first approach, The Promise.all(iterable) method takes an iterable as input. In your case, fetch_leads_new and fetch_leads_pending is already returning an array of pending Promise, something like
: [ Promise { <pending> }, Promise { <pending> } ].
So currently you are passing an array with arrays or pending promise(Promise.all([fetch_leads_new, fetch_leads_pending])) to the Promise.all function, something like
Promise.all([[ Promise { <pending> }, Promise { <pending> } ], [ Promise { <pending> }, Promise { <pending> } ]])
So I think you can consider having two Promise.all methods with await one for fetch_leads_new other for fetch_leads_pending
const newRecords = await Promise.all(fetch_leads_new);
const pendingRecords = await Promise.all(fetch_leads_pending);
const leads_status_statics = [
{
New: newRecords,
},
{
Pending: pendingRecords,
},
];
Regarding the second approach
When the fetchMonths has more that one entry that means res.status(200).json(... is also called more than once(In each iteration of map function) and that why you are getting Cannot set headers after they are sent to the client error