Let's take a look at this setup I have:
Model:
export class MapDetailModel{
id: number;
lat: number;
lon: number;
alt: number;
long: number;
angle: number;
distance?: number;
pendenza?: number;
}
Html:
<div class="element-list">
<form [formGroup]="survey" novalidate (ngSubmit)="onSubmit(survey)" *ngIf="items">
<div formArrayName="sections">
<div class="single-item" *ngFor="let section of getSections(survey); let i = index">
<div [formGroupName]="i">
Lat: <input type="text" formControlName="lat" class="frm-txt">
Lon: <input type="text" formControlName="lon" class="frm-txt">
Long: <input type="text" formControlName="long" class="frm-txt">
Angle: <input type="text" formControlName="angle" class="frm-txt">
a: {{i.angle}}
<a (click)="updateData(i)">Update data</a>
</div>
</div>
</div>
</form>
</div>
ts:
@Component({
//moduleId: module.id,
changeDetection: ChangeDetectionStrategy.OnPush,
selector: 'my-info-bar',
templateUrl: 'map-info-bar.component.html',
styleUrls: ['map-info-bar.component.css'],
providers: [],
})
export class MapInfoBarComponent implements OnInit, OnDestroy
{
zoomLevels: any[];
points: MapDetailModel[] = [];
isAlive = true;
survey: FormGroup;
items = false;
constructor(
private mapService: MapService,
private fb: FormBuilder,
private changeDetectorRef: ChangeDetectorRef
){}
ngOnInit() {
this.mapService.singlePointChanged
.takeWhile(() => this.isAlive)
.subscribe( evt => {
if(!!evt && !!this.survey.value.sections[0]){
let elem;
this.points.forEach(el => {
if(el.id == evt.id){
el = evt;
elem = el;
}
});
(<FormArray>this.survey.get('sections')).at(elem.id).patchValue(elem);
this.changeDetectorRef.detectChanges();
}
})
this.mapService.pointsChanged
.takeWhile(() => this.isAlive)
.subscribe( evt => {
if(!!evt){
this.points = evt;
if(!this.items){
this.survey = this.fb.group({
sections: this.fb.array([
this.initSection(0),
]),
});
this.items = true;
} else {
this.addSection(this.points.length - 1);
}
}
});
}
initSection(idx: number) {
return this.fb.group({
lat: [this.points[idx].lat],
lon: [this.points[idx].lon],
long: [this.points[idx].long],
angle: [this.points[idx].angle]
});
}
addSection(idx: number) {
const control = <FormArray>this.survey.get('sections');
control.push(this.initSection(idx));
}
getSections(form) {
return form.controls.sections.controls;
}
updateData(index: number){
const values = this.survey.value.sections[index] as MapDetailModel;
this.mapService.setChangePoint(values);
}
ngOnDestroy(): void {
this.isAlive = false;
}
}
Everything is functioning smoothly until this line gets executed:
(<FormArray>this.survey.get('sections')).at(elem.id).patchValue(elem);This triggers the following error:
ERROR TypeError: Cannot read property 'patchValue' of undefinedHowever, the structure looks like this:
https://i.sstatic.net/cl4Dt.png
My question is, how can I update the formArray value at position elem.id? It seems odd that it's undefined even though the .get should locate the 'section' data.
Thank you for your help.