javascript - md-select error message trigger in angular material -

i have md-select , corresponding submit button use call web-service , pass data md-select (i not using forms here):

<div class="col-8">     <md-select placeholder="select user" class="custom-select" id="user" name="user" [(ngmodel)]="user" floatplaceholder="never">         <md-option *ngfor="let user of users| keys" [value]="user.key">{{user.value}}</md-option>     </md-select> </div> <div class="col-2 mb-3">     <button type="button" class="btn blue-btn" (click)="ws(user)">view details</button> </div> 

upon submit , before calling web-service, want check whether option has been selected , display error message (angular material style) in case none is. angular documentation mentions errorstatematcher mdinput none md-select.

make use of ngmodelchange

<md-select placeholder="select user" class="custom-select" id="user" name="user" [(ngmodel)]="user" floatplaceholder="never" (ngmodelchange)="changeselected($event)">         <md-option *ngfor="let user of users| keys" [value]="user.key">{{user.value}}</md-option>     </md-select> 

component

changeselected(event) {   this.user = event.user; }