Angular 5 material: dropdown (select) required validation is not working

问题

I have a material dropdown inside my ngForm, when I set this select as required it shows an asterisk * beside it but the form is seen as valid if I don't select any option from the dropdown.

<mat-form-field class="col-4 offset-1">
<mat-select placeholder="Some placeholder" [(value)]="data.name" required>
  <mat-option *ngFor="let name of names" [value]="name.value">
    name.viewValue
  </mat-option>
</mat-select>
</mat-form-field>

This is unlike what happens if I set the material input to required which will make the form invalid if it is empty.

<mat-form-field class="col-4 offset-1">
 <input matInput name="dob" placeholder="Date Of Birth" [(ngModel)]="data.dob" required>
  </mat-form-field>

I prefer to solve this using a template driven approach not by using ReactiveForms ( I found some solution talking about the ReactiveForms), can anyone help me?

Note:

I found a question of similar title but it is using FormGroup (reactiveForms)

I have put an example to give an idea in this stackblitz

回答1:

You added required to the select's option, not the select. Do it like:

<mat-form-field>
  <mat-select placeholder="Favorite food" name="select" [(ngModel)]="select" required>
    <mat-option *ngFor="let food of foods" [value]="food.value" >
      {{ food.viewValue }}
    </mat-option>
  </mat-select>
</mat-form-field>

DEMO

回答2:

Based on the excellent answer of (from zero to hero), I want to clarify 2 points mentioned in comments:

1- You have to use ngModel not value

2- You have to give the control a name

Full credit goes to him, I wanted to clarify this to any newcomer like me as it took me 2 hours to find out why it doesn't work

来源：https://stackoverflow.com/questions/50087495/angular-5-material-dropdown-select-required-validation-is-not-working