ngOnInit中的ExpressionChangedAfterItHasBeenCheckedError

Question

I've got my HTTP interceptor to open loading bar each time HTTP request is made:

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);
        });
    }

Then in my data-storage-service I have a subject:

openProgressbar = new Subject<boolean>();

And I listen to it in my app component, where I placed my loading bar:

ngOnInit() {
    this.dataStorageService.openProgressbar.subscribe(czyOtworzyc => {
        this.alertMessageNavbarStatus = true;
    });
}

But the ExpressionChangedAfterItHasBeenCheckedError is showing. I was looking for solution with using ngAfterContentChecked but it didn't work for me. Could anybody help me?

Answer 1

Inject ChangeDetectorRef into the component

import { ChangeDetectorRef } from '@angular/core';

constructor(private _changeDetectorRef: ChangeDetectorRef) {}

Run change detection manually

ngOnInit() {
    ...
    this._changeDetectorRef.detectChanges();
}