Clear mat-select selection Angular material - html

Question

I have implemented mat-multi-select option. I have a search functionality and I am able to select multiple options at once. Post selection when I click generate button, I want to clear all the selections. I am able to clear the values from search bar but values are still selected if I open the multi select dropdown. How can I clear those values.
HTML Code
<mat-select [formControl]="cMultiCtrl" [multiple]="true" required (selectionChange)="selectionChange($event)">
<mat-option>
<ngx-mat-select-search placeholderLabel="Search" noEntriesFoundLabel="No Matching Value Found" [formControl]="cMultiFilterCtrl"></ngx-mat-select-search>
</mat-option>
<mat-option *ngFor="let val of filteredCMulti | async" [value]="val.value">
{{val.name}}
</mat-option>
</mat-select>
// the button on click of which I want to clear everything post API call
<button mat-raised-button (click)="generate()" class="download-button">Generate
</button>
TS Code
public filteredCMulti: ReplaySubject<any[]> = new ReplaySubject<any[]>(1);
public cMultiCtrl: FormControl = new FormControl();
ngOnInit() {
this.filteredCMulti.next(this.cvalues.slice());
this.cMultiFilterCtrl.valueChanges
.pipe(takeUntil(this._onDestroy))
.subscribe(() => {
this.filterBanksMulti();
});
}
ngAfterViewInit() {
this.setInitialValue();
}
ngOnDestroy() {
this._onDestroy.next();
this._onDestroy.complete();
}
private setInitialValue() {
this.filteredCMulti
.pipe(take(1), takeUntil(this._onDestroy))
.subscribe(() => {
this.singleSelect.compareWith = (a, b) => a.id === b.id;
});
}
selectionChange(event){
this.cvalue = event.value;
}
private filterBanksMulti() {
if (!this.cvalues) {
return;
}
let search = this.cMultiFilterCtrl.value;
if (!search) {
this.filteredCMulti.next(this.cvalues.slice());
return;
} else {
search = search.toLowerCase();
}
// filter the banks
this.filteredCMulti.next(
this.cvalues.filter(bank => bank.name.toLowerCase().indexOf(search) > -1)
);
}
generate(){
let msg = '';
// some logic here
else{
this.commonService.showSnackBar("Value generated")
this.filteredCMulti = new ReplaySubject; // this clears the search bar but not values, they are still selected
this.table();
}}
})
}

Answer 1

Provide an element ref to your <mat-select>
<mat-select #matRef [formControl]="cMultiCtrl" [multiple]="true" required (selectionChange)="selectionChange($event)">
<mat-option>
<ngx-mat-select-search placeholderLabel="Search" noEntriesFoundLabel="No Matching Value Found" [formControl]="cMultiFilterCtrl"></ngx-mat-select-search>
</mat-option>
<mat-option *ngFor="let val of filteredCMulti | async" [value]="val.value">
{{val.name}}
</mat-option>
</mat-select>
And update your ts file like:
#ViewChild('matRef') matRef: MatSelect;
clear() {
this.matRef.options.forEach((data: MatOption) => data.deselect());
}
You can optimize clear() by conditionally calling deselect()