How to validate select?

Sorry if this already been, but i’m new to the ionic2…

Currently I have this code:

<ion-item *ngIf="type == 'channels'">
	<ion-label stacked color="primary">Channels</ion-label>
	<ion-select [(ngModel)]="data.channel" name="channels" placeholder="Select Channel" #channel="ngModel">
		<ion-option *ngFor="let channel of channels" value="{{ channel.id }}">{{ channel.description }}</ion-option>
	</ion-select>

	<p [hidden]="channel.valid || submitted == false" color="danger" padding-left>
		Channel is required
	</p>
</ion-item>

How to make sure that value is selected?