allow returning promise

**I’m submitting a…

[ ] Regression (a behavior that used to work and stopped working in a new release)
[x] Bug report  <!-- Please check the repository for a similar issue or PR before submitting -->
[ ] Support request => <!-- Please check the repository for a similar issue or PR before submitting -->
[x] Feature request
[ ] Documentation issue or request

Current behavior

1. Using an Angular app (v. 5.2.6), import the following into app.module:

ConfigModule.forRoot({
  deps: [HttpClient],
  provide: ConfigLoader,
  useFactory: configFactory,
}),

where configFactory is:

export function configFactory(http: HttpClient): ConfigLoader {
  return new ConfigHttpLoader(http)
}

Then use getSettings in a service:

@Injectable()
export class MyService {
  constructor(private configService: ConfigService) {
    const url = configService.getSettings("api.url", "")
  }
}

url would always be empty string, when in my config.json file was this:

{
  "api": {
    "url": "www.example.com/api"
  }
}

This is mainly because the HttpLoader is most likely not finished with getting config.json by the time the constructor in my service calls getSettings.

Expected/desired behavior Same code, except have two methods: getSettingsSync and getSettings, where getSettings returns a Promise or Observable when the service is finished with getting the settings.

Then in my code, I would go back to MyService and do this:

constructor(private configService: ConfigService) {
  const url = await configService.getSettings("api.url")
}

What is the motivation / use case for changing the behavior? It is nice to have the getSettings method to always return your expected configuration. Since it didn’t do this, it took me about 2-4 hours to realize why.

Environment

• Angular version: 5.2.6

• Browser:

• Chrome (desktop) version XX
• Chrome (Android) version XX
• Chrome (iOS) version XX
• Firefox version XX
• Safari (desktop) version XX
• Safari (iOS) version XX
• IE version XX
• Edge version XX

[FritzHerbers]

@fulls1z3 I have the same or a similar problem.

Your HTTP interceptor will/might solve the problem when ConfigService is not yet initialized. It does not solve the problem with a call to GetSettings (within mergeMap) with a resolved ConfigService as the HTTP request initiated by the ConfigHttpLoader has not yet returned data.

I have a service, in the constructor I receive an initialized ConfigService, but the call to GetSettings fails, as no config is yet available. (I think the OP has the same problem).

Is there a possibility to wait for the HTTP request to finish before calling getSettings or have getSettings to wait until the config is available ?

[unlight]

As a stop gap solution CustomConfigHttpLoader

import { ConfigHttpLoader } from '@ngx-config/http-loader';
import pDefer from 'p-defer';

export class CustomConfigHttpLoader extends ConfigHttpLoader {
    readonly onLoadSettings = pDefer();

    async loadSettings(): Promise<void> {
        const result = await super.loadSettings();
        this.onLoadSettings.resolve();
        return result;
    }
}

in other app initializer

(configService.loader as CustomConfigHttpLoader).onLoadSettings.promise.then(() => {
console.log('loaded');
}));