Leave some input select Multiple(Angular Material) pre-marked

Question

I am using Angular Material in my application, and it in turn has this list created to fill in my input:

lista: any[] = [
{
  name: 'Cursos',
  tribunais: [
    { value: 'RDC1'},
    { value: 'RDC2'},
    { value: 'RDC3'},
    { value: 'RDC4'},
    { value: 'RDC5'},
    { value: 'INF' }
  ]
}
]

And I have my HTML component, which renders this list:

<mat-form-field>
 <mat-select placeholder="Cursos" multiple>
  <mat-optgroup *ngFor="let group of lista" [label]="group.name" [disabled]="group.disabled">
  <mat-option *ngFor="let tribunais of group.tribunais" [value]="tribunais.value">
    {{tribunais.value}}
  </mat-option>
</mat-optgroup>
</mat-select>
</mat-form-field>

And he looks like this:

However I want to leave some pre-marked inputs when I start my component, as I do to leave marked some options pre-defined?

Answer 1

As quoted in documentation, you can create a list with the results and you can already put the values of value included in that list.

public selecionados = [RDC1, RDC4];

and then make Binding, data connection with html, from the created list

<mat-select [(ngModel)]="selecionados " ...>
</mat-select>

Update:

public selecionados = ['RDC1', 'RDC4'];

Add single quotes to the list items as the resulting list should be string, since the values of each selected item is also a string. I made an example in stackbliz.

Uppdate 2:

To analyze the values of selected

{{ selecionados | json }}
<mat-select [(ngModel)]="selecionados " ...>
</mat-select>