Replace value of ngModel if not exists

Question

I have a conditional field in a form like this:

<mat-form-field *ngIf="model.personIsMarried === 'Yes'">
    <input type="number" 
      matInput id="personSpouseAge" 
      [(ngModel)]="model.personSpouseAge"
      name="personSpouseAge" 
      placeholder="Spouse Age"
  </mat-form-field>

If the user is not married the value of model.personSpouseAge is undefined. What I want is to set the value of model.personSpouseAge to the model.personAge field that was previously filled, for example:

The person filling the form is age 27 and is not married, so the model.personSpouseAge field value will also be 27.

I hope to be clear. Thanks for your help.

Answer 1

In html:

[ngModel]="model.personSpouseAge"
(ngModelChange)="setPersonSpouseAge(model)"

In .ts:

setPersonSpouseAge(model) {
  model.personSpouseAge = model.personSpouseAge || model.personAge
}