[FR] APP_BASE_HREF useFactory Promise Support

I’m submitting a…

[x] Feature request

Current behavior

APP_BASE_HREF useFactory doesn’t support promises, only values.

Expected behavior

APP_BASE_HREF useFactory supports both values and promises.

What is the motivation / use case for changing the behavior?

In my application I need to set APP_BASE_HREF asynchronously. Unfortunately, APP_BASE_HREF useFactory doesn’t support promises. So, I tried this approach with APP_INITIALIZER, but failed as well as OP, because it seems like if you do AJAX requests in APP_INITIALIZER useFactory, you should setup APP_BASE_HREF first.

APP_INITIALIZER supports promises in useFactory, so it would be very useful if APP_BASE_HREF supports them too.

Environment

Angular version: 6.0.0

Browser:
- [x] Chrome (desktop) version 69

[VitaliPark]

Here’s another use case, when supporting promises in APP_BASE_HREF might be useful: You need to set app base href dynamically using external configuration.

• In order to get this external configuration you can use APP_INITIALIZER (download config file via http call)
• But then, in useFactory of APP_BASE_HREF provider you need to wait for this call to finish to get config. And since you can only use value there, it’s not possible (correct me if I’m wrong). Seems like currently the only way to do so, is to move config loading into main.ts file, and bootstrap application only after all configs are loaded and pass config in extra providers like so (again correct me if I’m wrong) :

fetchConfig().then(config => {
	platformBrowserDynamic([{provide: ConfigData, useValue: config}])
		.bootstrapModule(AppModule)
		.catch(err => console.log(err));
});

Which seems like a hack, especially when APP_INITIALIZER is used specifically for app initialization, but you can’t use it in this particular case.

The same issue is described here: https://stackoverflow.com/questions/46190280/angular-2-set-app-base-href-with-a-value-from-a-promise-observable

[angular-robot[bot]]

Just a heads up that we kicked off a community voting process for your feature request. There are 20 days until the voting process ends.

Find more details about Angular’s feature request process in our documentation.