Navigation triggered outside Angular zone, did you

问题:

I am using Angular 7 and facing an issue => after login the API GET calls successfully and the component receiving data too, but UI is not displaying that data.

When I open the browser console, immediately the data gets populated on the UI and a warning is showing in the console.

"core.js:15686 Navigation triggered outside Angular zone, did you forget to call 'ngZone.run()'?"

I have googled this warning and found some workaround like this.ngZone.run() and call my API's inside it.

But the issue is, I am using more than 40 components and calling so many API in each component. So I have to call ngZone.run() on each API call, which seems to be difficult to do.

Please suggest me the better approach to overcome this issue. Thanks in advance.

app.component.ts

getEmployees(): void {
    this.employeeService.getEmployees().subscribe(e => {
        this.employees = e;
    });
}

app.service.ts

@Injectable()
export class EmployeeService {
    constructor(private httpClient: HttpClient) { }

    getEmployees() {
        return this.httpClient.get<EmployeeModel[]>('employees');
    }

回答1:

Usually this happens when you are wrapping angular calls inside some external js callback, from external JavaScript not related to angular code.

Example app.component.ts:

callMyCustomJsLibrary() {
  googleSdk.getLocations(location => this.getEmployees());
}

getEmployees(): void {
    this.employeeService.getEmployees().subscribe(e => {
        this.employees = e;
    });
}

In this case you will have to include the call into the NgZone, example: this.ngZone.run(() => this.getEmployees());

The app.component.ts would then look like the following:

callMyCustomJsLibrary() {
  googleSdk.getLocations(location => this.ngZone.run(() => this.getEmployees()));
}

getEmployees(): void {
    this.employeeService.getEmployees().subscribe(e => {
        this.employees = e;
    });
}

回答2:

If i talk from top then meaning of the this warning is that event is trigger outside of zone i.e. if you know about zones or also called execution context which angular is used for change detection and UI rendering. so while navigration it is expected by the angular to re renderer the UI but it is not happening here that's the problem you are facing. so it throw this warning because angular process the change detection and UI rendering when the code executed lies inside of angular zone.

But actually This warning comes when you trying to call the router navigration inside the subscribe method.

Put your router navigation call outside of subscribe method and it will not throw this warning again. and you will see the expected UI after navigation.

for more info about zones read and watch the video mention below:-

https://blog.thoughtram.io/angular/2017/02/21/using-zones-in-angular-for-better-performance.html#running-outside-angulars-zone

https://www.youtube.com/watch?v=3IqtmUscE_U&t=150

回答3:

This happens if you try injecting a custom made service:

constructor(private myService: MyService) {
}

while you forgot to provide it in the module configuration:

@NgModule({
  providers: [
    MyService
  ]