update page content - components

Question

I have a morris chart that compares different students statistics. I also have a modal in which I can add a new student and the graph should update with new student statistics. After adding, the graph is getting updated but only when I refresh the whole page. How would I update the page without refreshing?
component.ts
ngOnInit() {
this.getData();
}
getData() {
this.http.get('url')
.subscribe(data => {
const graphData = data.stathistory;
const graphDataArr = [];
let currentChar = 'a';
for (const graphdata in graphData) {
const curDate = graphdata.replace(/(\d{4})(\d{2})(\d{2})/g, '$1-$2-$3');
const graphdataObj = { 'y': curDate };
for (const element in graphData[graphdata]) {
graphdataObj[currentChar] = Number(graphData[graphdata][element].rank);
currentChar = this.nextChar(currentChar);
}
graphDataArr.push(graphdataObj)
currentChar = 'a';
}
const yKeysArr = [];
for (let i = 0; i < data.domains.length; i++) {
yKeysArr.push(currentChar);
currentChar = this.nextChar(currentChar);
}
this.generateChart(graphDataArr, data.names, yKeysArr);
});
}
generateChart(graphRanks = [], names = [], yKeys = []) {
this.graphData = graphRanks;
this.graphOptions = {
xkey: 'y',
ykeys: yKeys,
labels: names,
resize: true,
parseTime: false,
pointSize: 0,
};
}
addStudent(name) {
this.http.post('url', {
name: name,
})
.subscribe(response => {
this.getData();
}
);
}
html
<div *ngIf = 'graphData' mk-morris-js [options]="graphOptions" [data]="graphData" type="Line" style="height: 500px; width: 100%;">
**code for modal dialog**
<button type="button" class="btn btn-primary" (click)="addStudent(name)">
Please let me know if more info is needed.

Answer 1

This looks fine. I would suggest you to add console.log(graphRanks); just before this.graphData = graphRanks; to ensure that the new data is loaded when expected. By the way your button calls the function addDomain(name) while in your script the function name is addStudent(name).

Answer 2

I would recommend that you make your graphData an observable and use the async pipe in your html. Something like this:
graphData$ = this.http.get('url').pipe(
map(x => // do stuff with x here)
)
Then, in your html you can make:
[graphData]="graphData$ | async"
Here is a good post by Todd Motto on the ng-if piece:
https://toddmotto.com/angular-ngif-async-pipe
EDIT:
If you don't want to make your graphData an observable - you could probably use a switchMap in you addStudent function.
addStudent(name) {
this.http.post('url', {
name: name,
})
.pipe(
switchMap(x => this.getData())
}
);
}

Answer 3

I finally got it working. I tried to clear the morris chart and generate the chart with new data. So, whenever there is a data change, it would clear the graph and redraw the graph with new data.
Clearing the chart
document.getElementById('idofthegraph').innerHTML = '';
This would draw the chart again
this.generateChart(graphDataArr, data.names, yKeysArr);