Clear Angular Material autocomplete after selection

Question

The problem I'm having is the following: the behaviour I need is, when an option is selected from the autocomplete input, it should add a chip to the Angular Material Chips component (which it does) and it should also clear the autocomplete input, so I can then select another option.

This is my html:

<div class="col-md-6">
   <md-form-field>
      <input type="text" placeholder="Categoría" aria-label="Categoría" mdInput [mdAutocomplete]="auto" [formControl]="categoryCtrl">
      <md-autocomplete #auto="mdAutocomplete" (optionSelected)="selectCategory($event)">
         <md-option *ngFor="let category of filteredCategories | async" [value]="category.name">
            {{ category.name }}
         </md-option>
      </md-autocomplete>
   </md-form-field>
</div>

This is my TypeScript code:

constructor(private placeService: PlaceService, private categoryService: CategoryService) {
    this.categoryCtrl = new FormControl();
    this.filteredCategories = this.categoryCtrl.valueChanges
        .startWith('')
        .map(category => category ? this.filterCategories(category) : this.categories.slice());
}

filterCategories(name: string) {
    return this.categories.filter(category => category.name.toLowerCase().indexOf(name.toLowerCase()) === 0);
}

selectCategory(category: any) {
    const index = this.selectedCategories.indexOf(category.option.value);
    if (index === -1) {
        this.selectedCategories.push(category.option.value)
    }
}

I've checked the Angular Material documentation and I haven't found a method to do this.

Thanks.

Answer 1

I think you're close, it looks like the only missing piece is resetting the form control value in selectCategory . This is how we accomplished it in our own app, but it's effectively the same thing:

/** Reference to the autocomplete trigger. */
@ViewChild(MdAutocompleteTrigger)
private trigger: MdAutocompleteTrigger;

/** Form control for the input. */
searchControl = new FormControl('');

ngAfterViewInit() {
  // Clear the input and emit when a selection is made
  this.trigger.autocomplete.optionSelected
    .map(event => event.option)
    .subscribe(option => {
      // This may or may not be needed, depending on your purposes
      option.deselect();

      // Emit the selection (so parent component can add chip)
      this.selection.emit(option.value);

      // Reset the value of the input
      this.searchControl.setValue('');
    });
}

Whenever you select a value, there will be a brief "flash" of the selected text. To avoid this, you can use the displayWith property to just display selected values as empty:

<md-autocomplete #auto="mdAutocomplete" [displayWith]="displayNull">
  ...
</md-autocomplete>

/** Display function for selected autocomplete values. */
displayNull(value) {
  return null;
}

Answer 2

Here my approach

in template

...
<md-autocomplete #auto="mdAutocomplete" [displayWith]="displayNull" (optionSelected)="selectHandler($event)">
...

in component.ts

public selectHandler(event : MdAutocompleteSelectedEvent) : void
{
    event.option.deselect()
    this.doStuffWith(event.option.value)
}

public displayNull()
{
    return null
}

Answer 3

Came across this solution, but I didn't like the displayNull fix.

My solution looks similar to this:

component.html:

  <input matInput [matAutocomplete]="auto" (input)="filter($event.target.value)" #autoInput>
  <mat-autocomplete #auto [displayWith]="displayKey" (optionSelected)="emit($event, autoInput)">
  // ...
  </mat-autocomplete>

component.ts:

@Output() optionSelected = new EventEmitter<MatAutocompleteSelectedEvent>();

emit(event: MatAutocompleteSelectedEvent, ele: HTMLInputElement) {
  ele.value = '';
  ele.blur();
  this.filter('');
  this.optionSelected.emit(event);
}

Answer 4

If you are using reactive forms the easiest way is to get the control and set the value to an empty string

• Get the control: https://angular.io/api/forms/AbstractControl#get
• Set the value: https://angular.io/api/forms/AbstractControl#setvalue

In my case i had to do:

<input [matAutocomplete]="auto" formControlName="currentContact" type="text" matInput placeholder="Locatie">

this.reactiveForm = this.formBuilder.group({currentContact: ['']})
this.reactiveForm.get('currentContact').setValue('');