Is it possible to select all options in an Angular mat-select component using a Boolean function

Is there a way to enable Select All functionality in Angular mat-select by using Boolean functions without the need for form tags or form builders?

Component.html

<div layout="column" class="mat-cloumn w-25">
  <mat-form-field appearance="fill">
    <mat-label>Location</mat-label>
    <mat-select class="user-control" multiple>
      <mat-option #allSelected (click)="toggleAllSelection()" [value]="0">All</mat-option>
      <mat-option  [value]="store.id" *ngFor="let store of stores">{{ store.name }}</mat-option>
    </mat-select>
  </mat-form-field>
</div>

component.ts

  notSelectedAll = true;

  stores = [
    {id:1,name:'store - 1'},
    {id:2,name:'store - 2'},
    {id:3,name:'store - 3'},
    {id:4,name:'Store - 4'}
  ];

toggleAllSelection(){
  if(this.notSelectedAll = !this.notSelectedAll){
    console.log(false)
  }else{
    console.log(true)
  }
}

Looking for a solution to implement select all feature in angular mat-select

Answer №1

When working with a MatSelect that allows multiple selections, you need to pass an array of values.

If you want to enable toggling all nodes by clicking on one option, you'll need to create a function that updates all the values in the MatSelect, hence requiring an additional variable.

Below is a template example:

<mat-form-field appearance="fill">
 <mat-select [value]='value' class="user-control" multiple>
    <mat-option #allSelected (click)="toggleAllSelection()" [value]="0">All</mat-option>
    <mat-option [value]="store.id" *ngFor="let store of stores"
(click)="valueChange(store.id)" >{{ store.name }}</mat-option>
</mat-select>

And in the .ts file:

export class AppComponent {

   value = [];

   selectAll = false;

   stores = [
     { id: 2, name: "store - 1" },
     { id: 3, name: "store - 2" },
     { id: 4, name: "store - 3" },
     { id: 5, name: "Store - 4" }
   ];

  constructor(private fb: FormBuilder) {}

  ngOnInit() {}

  // Function to handle value changes for each MatOption
  valueChange(id: number) {
  if (this.value.indexOf(id) > -1) {
  const pos = this.value.indexOf(id);
  this.value.splice(pos, 1);
  } else {
  this.value.push(id);
 }
}

  //Function to toggle selecting or deselecting all options
  toggleAllSelection() {
  this.selectAll = !this.selectAll;
  if (this.selectAll == true) {
    this.value = [0, 2, 3, 4, 5];
  } else {
    this.value = [];
   }
 }
}

(Edit after missing function for single value).

Since there's no usage of Angular forms here, manual handling is required to ensure proper communication between MatSelect and the UI output.

The value variable stores the selected nodes and is also used in the mat-form-field template to synchronize selections with MatOptions.

Here is a link to the updated stack blitz : https://stackblitz.com/edit/angular-material-with-angular-v5-3arsoh?file=app/app.component.html

You could potentially reduce the code by using a formControl instead of FormGroup or FormBuilder if needed.

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