NodeJS (Express) + MongoDB + Angular stream a request - node.js

Question

I want to stream a MongoDB query in NodeJS because, in Angular, i have a chart and i want to update the data without making a refresh.
So far, this is my code (NodeJS):
exports.gettoday = function (request, response) {
db.collection("nifi5", function (err, collection) {
collection
.aggregate([
{
$group: {
_id: {
minute: {
$minute: { $dateFromString: { dateString: "$created_at" } },
},
hour: {
$hour: { $dateFromString: { dateString: "$created_at" } },
},
day: {
$dayOfMonth: { $dateFromString: { dateString: "$created_at" } },
},
month: {
$month: { $dateFromString: { dateString: "$created_at" } },
},
year: {
$year: { $dateFromString: { dateString: "$created_at" } },
},
},
avg: { $avg: "$value_temperature" },
},
},
])
.stream()
.toArray(function (err, items) {
if (err) {
response.statusMessage = {
devMessage: err,
clientMessage: "Unexpected error, try again latter",
};
response.send(response.statusMessage).end();
}
let tarray = { labels: [], data: [] };
items.forEach((element) => {
element.date = element._id.hour + ":" + element._id.minute;
element.avg = Math.round(element.avg * 100) / 100;
});
items.sort(function (a, b) {
return a.date < b.date ? -1 : 1;
});
items.forEach((element) => {
tarray.labels.push(element.date);
tarray.data.push(element.avg);
});
return response.json(tarray);
});
});
};
Angular:
gettodaydata(): Observable<any> {
return this.http.get(`${environment.baseURL}gettoday`).subscribe((data) => {
this.data_line.push(...data.data);
this.labels_line.push(...data.labels);
this.isLineChartLoading = false;
});
}
Can u please help me streaming this controller and fetch the data in Angular to update my chart when new data comes do my database ?
Thank you all!

Answer 1

You should give a try to socket.io, it creates a persistent connection and responds to events in real time.