Get selected ngModel value in Angular / Ionic 2?

问题

How can I get the selected option in constructor / function, using Angular / Ionic 2?

<ion-item>
    <ion-label>Quantity</ion-label>
    <ion-select [(ngModel)]="qty">
        <ion-option value="1" selected="true">1</ion-option>
        <ion-option value="2">2</ion-option>
        <ion-option value="3">3</ion-option>
    </ion-select>
</ion-item>

<button ion-button full (click)="addToCart()">Buy Now</button>

I've tried this:

export class ProductPage {
    qty: any;

    constructor(public navCtrl: NavController) {

    }

    addToCart() {
        console.log(this.qty);
    }
}

回答1:

<ion-item>
    <ion-label>Quantity</ion-label>
    <ion-select [(ngModel)]="qty">
        <ion-option [value]="1" selected="true">1</ion-option>
        <ion-option [value]="2">2</ion-option>
        <ion-option [value]="3">3</ion-option>
    </ion-select>
</ion-item>

try this

export class ProductPage implements OnInit{
    qty: any;

    ngOnInit() {
        console.log(this.qty);
    }
}

Please read : https://angular.io/guide/lifecycle-hooks

来源：https://stackoverflow.com/questions/44937103/get-selected-ngmodel-value-in-angular-ionic-2