Question

每次发出HTTP请求时，我都有HTTP拦截器打开加载栏：

intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
const dataStorageService = this.injector.get(DataStorageService);
dataStorageService.openProgressbar.next(true);
return next
    .handle(req)
    .do(evt => {
         if (evt instanceof HttpResponse) {
             dataStorageService.openProgressbar.next(false);
        }
    })
    .catch(err => {
        return Observable.throw(err);
    });
}

然后在我的数据存储服务中，我有一个主题：

openProgressbar = new Subject<boolean>();

然后我在我的应用程序组件中放置了加载栏：

ngOnInit() {
    this.dataStorageService.openProgressbar.subscribe(ifOpen: boolean => {
        this.alertMessageNavbarStatus = ifOpen;
    });
}

html：

<div id="Intro" *ngIf="alertMessageNavbarStatus">
<app-progress-bar-indeterminate-example>
</app-progress-bar-indeterminate-example>
</div>

但是正在显示ExpressionChangedAfterItHasBeenCheckedError。我一直在寻找使用ngAfterContentChecked的解决方案，但对我而言不起作用。有人可以帮我吗？

Answer 1

IMO将您的条件逻辑放入setTimeout技巧中，就像这样-

setTimeout(() => {
    this.dataStorageService.openProgressbar.subscribe(ifOpen: boolean => {
        this.alertMessageNavbarStatus = ifOpen;
    });
},0);

有关更多详细信息，我强烈建议您阅读本文-

https://blog.angularindepth.com/everything-you-need-to-know-about-the-expressionchangedafterithasbeencheckederror-error-e3fd9ce7dbb4

ExpressionChangedAfterItHasBeenCheckedError-ngIf-隐藏/显示进度条

1 个答案: