constructor(private _service: LocatorService) {
this.counties = this.countyTerm.valueChanges
.debounceTime(300)
.distinctUntilChanged()
.switchMap((term: string) => _service.getCounties(term));
}
counties: Observable<County[]>;
countyTerm = new Control();
As expected, this.counties
is only populated once a value is entered into the countyTerm
bound control.
How can I trigger valueChanges
when this component is instantiated so that the set of counties is loaded initially?
I tried the following, but it had no effect ( implements OnInit
was added to the class):
ngOnInit() {
this.countyTerm.updateValue('', { emitEvent: true });
}
Just start your stream out with a fixed value. Something like this:
this.counties = Rx.Observable.of('')
.concat(this.countyTerm.valueChanges.debounceTime(300))
.distinctUntilChanged()
.switchMap((term: string) => _service.getCounties(term));
Use startWith RxJS operator to emit something before stream.
this.counties = this.countyTerm.valueChanges
.startwith('')
.debounceTime(300)
.distinctUntilChanged()
.switchMap((term: string) => _service.getCounties(term));
With RxJS 6 / 7 new syntax:
this.counties$ = this.countyTerm.valueChanges.pipe(
startWith(''),
debounceTime(300),
distinctUntilChanged(),
switchMap((term: string) => _service.getCounties(term))
);
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