Dears,Ionic VirtualScrool無法讀取屬性「長度」空
我試圖使用離子3的虛擬滾動,但它不工作。
我有我提供這樣的功能:
getActiveAds(){
return this.afDb.list<AngularFireList<any>>('/ads-active', ref => ref.orderByChild('adPlanPriority').startAt(1).endAt(3))
}
在我的列表頁,我有這個:
constructor(public navCtrl: NavController, public navParams: NavParams, public loadingCtrl: LoadingController, public adProvider: AdProvider) {
this.loading = this.loadingCtrl.create();
this.loading.present();
this.ads = this.adProvider.getActiveAds().valueChanges()
this.ads.subscribe((cat)=> {
this.loading.dismiss()
})
}
和我list.html這樣的:
<ion-list no-lines [virtualScroll]="ads | async">
<button ion-item *virtualItem="let ad" (click)="onAdSelect(ad)" class="aero-item ">
<ion-thumbnail item-start>
<img src="assets/images/noimage.jpg" />
</ion-thumbnail>
<h2>{{ ad.model}}</h2>
</button>
</ion-list>
隨着此代碼,我收到此錯誤:
Cannot read property 'length' of null
TypeError: Cannot read property 'length' of null
at VirtualScroll._stepDOMWrite (http://localhost:8100/build/vendor.js:92118:60)
at http://localhost:8100/build/vendor.js:92078:23
at dispatch (http://localhost:8100/build/vendor.js:20601:9)
at DomController._flush (http://localhost:8100/build/vendor.js:20545:13)
at rafCallback (http://localhost:8100/build/vendor.js:20534:22)
我在做什麼錯?
我不確定virtualScroll可以使用異步。嘗試用ngFor替換並查看結果 – Duannx