我需要一些帮助，在我的第一个离子-Angular 的应用程序...我试图显示类别列表，我一直得到这个错误在浏览器控制台.. Altho应用程序编译没有错误..控制台日志错误是：Uncaught (in promise): Error: NG02200: Cannot find a differ supporting object '[object Promise]' of type 'object'. NgFor only supports binding to Iterables, such as Arrays.
因此，我的应用程序的结构是，我有一个categories.service.ts，在其中我可以获得如下所示的类别：
export class CategoriesService {
categories: any = [];
constructor(
private authService: AuthenticationService,
private httpClient: HttpClient,
) { }
async getCategories() {
const token = await Preferences.get({ key: 'TOKEN_KEY' });
const headers = new HttpHeaders().set('Authorization', `Bearer ${token.value}`);
this.httpClient.get(`${environment.apiUrl}categories`, {headers}).subscribe(
data => {
this.categories = data;
},
error => {
console.log('Error', error);
}
);
}
}那么在我的categories.page.ts中我的代码是：
categories: any = [];
constructor(
private categoriesService: CategoriesService
) {}
ngOnInit() {
this.getCategories();
}
getCategories() {
this.categories = this.categoriesService.getCategories();
}在html中，我尝试这样显示它们：
<ion-col size="6" *ngFor="let category of categories">
<div id="{{category.seo_url}}" class="card">
<div class="card-overlay"></div>
<div class="card-cat-title">
<h4><a routerLink="/category/{{category.seo_url}}">{{ category.name }}</a></h4>
</div>
</div>
</ion-col>我做错了什么？请帮助：）
2条答案
按热度按时间holgip5t1#
categoriesService.getCategories() is not returning an array, is returning a Promise, which is an asynchronous action.
You have two options: await the response or resolve the Promise:
a) resolve the promise:
b) await the promise:
But notice that in this case you have to add the async keyword to the function.
5vf7fwbs2#
您的Angular 知识有差距。请检阅英雄https://angular.io/tutorial之旅。