Spring auto-configuration features

@heruan commented on Thu Dec 07 2017

When building many apps with Flow, I want to be able to create modules with shared/configurable routes and override them if needed, so that I do not have to duplicate code or write classes for the sole purpose to annotate them with @Route.

Use case:

@Route("${acme.login-route:login}")
@ConditionalOnMissingRoute
public class LoginComponent extends VerticalLayout { /* ... */ }

This could be in a module shared by many apps, each of one can override the default route in its own configuration file or override it completely with a new component if annotated with the same path.

@Legioth commented on Thu Dec 07 2017

Seems like there are two low level features at play here:

• Support ${<expression>} in @Route values, specific to our Spring add-on
• @ConditionalOnMissingRoute as a generic Flow feature to opt out from conflicts if there are multiple routes for the same location.

@heruan commented on Thu Dec 07 2017

Indeed. At first I considered @ConditionalOnMissingRoute as part of the add-on too, since @ConditionalOn[...] is a common convention in Spring Starters. But having it native in Flow could be useful for non-Spring developers too.

@Legioth commented on Thu Dec 07 2017

The functionality is indeed generically useful, but on the other hand the @ConditionalOn naming is quite specific to Spring.

@heruan commented on Wed Jan 03 2018

Another useful feature for Spring configuration (e.g. via properties/yml files) could be enabling push (and async servlet support).

Start by separating the requested capabilities: configurable ${...} values in @Route, @ConditionalOnMissingRoute, and Spring properties or YAML support for push and async servlet configuration. Read the discussion around @Route and the proposed annotation, then define separate acceptance criteria for each feature before identifying implementation entry points and tests.