GET request with $function in Mongodb - node.js

Question

Summary:
I am trying to Combine the result of Mongodb aggregation with a third party API and I can't find anything relevant to it.
Explanation:
The below Express route finds all Games that comes after the provided Date and have not been cancelled. The next step is to get some data of that single game from the Third party API and attach it to the object and continue further in the pipeline
Issue:
It seems that you can't have a XHR request inside the $function (I didn't find anything in the official documentation so I'm not sure on that)
const today = moment();
today.year(2021);
today.month(5);
let response = await Game.aggregate([
{
$match: {
$expr: {
$and: [
{ $gte: ["$date", moment(today).startOf('day').toDate()] },
{ $eq: ["$canceled", false] },
]
}
}
},
{ $sort: { date: 1 } },
{
$addFields: {
boxScore: {
$function:
{
body: async function (season, week, home_team) {
const result = await axios.get(
`SINGLEGAMEURL/${season}/${week}/${home_team}`,
{
headers: {
'Subscription-Key': 'SOMEKEY',
},
}
);
return result.data;
},
args: ["$season", '$week', 'home_team'],
lang: "js"
}
}
}
}
]);
I would really appreciate any help/direction on this, Cheers!

Answer 1

I doubt that you can use asynchronous functions in $function, because they return a promise that resolves to result.data, rather than the data themselves. Instead, consider performing the asynchronous operation in your express middleware, after the MongoDB operation. Something like this:
app.use("/path", async function(req, res) {
const today = moment();
today.year(2021);
today.month(5);
let response = await Game.aggregate([
{$match: ...},
{$sort: {date: 1}}
]).toArray();
await Promise.all(response.map(row => axios.get(
`SINGLEGAMEURL/${row.season}/${row.week}/${row.home_team}`,
{headers: {'Subscription-Key': 'SOMEKEY'}}
).then(function(result) {
row.boxScore = result.data;
})));
res.json(response);
});
(Probably the Promise.all can be avoided, but I'm not experienced enough with async/await to know how.)