在 Angular /w Electron 中在哪里执行初始化函数？

Question

I am using Angular and Electron, and I have a Preferences object I would like to initialize ( Preferences.init() ) which needs to be executed before any other code is executed . Does Angular or Electron have a specific location where such initialization code should be executed?

At the moment I put it into the constructor of AppComponent but since the function is asynchronous, I have a race condition and occasionally the data is not properly initialized when needed. Any help or suggestion is highly appreciated! Thanks!

Answer 1

You can use the APP_INITIALIZER dependency injection token to do a such thing:

Assuming you created a provider

@Injectable()
export class ThingProvider {

    private thing: Thing = null;

    constructor(private http: Http) {
    }

    public getThing(): Thing {
        return this.thing;
    }

    load() {
        return new Promise((resolve, reject) => {
            this.http
                .get('https://my-api.com/thing')
                .map(res => res.json())
                .subscribe(response => {
                    this.thing = response['value'];
                    resolve(true);
                })
        })
    }
}

Then, in your app.module.ts file:

export function thingsProviderFactory(provider: ThingProvider) {
  return () => provider.load();
}

And finally, in the same file:

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    HttpModule
  ],
  providers: [
    ThingProvider, 
    { provide: APP_INITIALIZER, useFactory: thingsProviderFactory, deps: [ThingProvider], multi: true }
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }