Lambda-based consumption of an ObjectProvider's object when available [SPR-16001]

[spring-projects-issues]

Andy Wilkinson opened SPR-16001 and commented

In a similar vein to #19474, I just wrote the following:

@Bean
public HttpHandler httpHandler(
		ObjectProvider<WebSessionManager> webSessionManagerProvider) {
	WebHttpHandlerBuilder builder = WebHttpHandlerBuilder
			.applicationContext(this.applicationContext);
	WebSessionManager webSessionManager = webSessionManagerProvider
			.getIfAvailable();
	if (webSessionManager != null) {
		builder.sessionManager(webSessionManager);
	}
	return builder.build();
}

I'd prefer to avoid the local variable and null check. Something like this:

@Bean
public HttpHandler httpHandler(
		ObjectProvider<WebSessionManager> webSessionManagerProvider) {
	WebHttpHandlerBuilder builder = WebHttpHandlerBuilder
			.applicationContext(this.applicationContext);
	webSessionManagerProvider.consumeIfAvailable(
			(webSessionManager) -> builder.sessionManager(webSessionManager));
	return builder.build();
}

---

Affects: 5.0 RC4

Issue Links:

• Provide computeIfAbsent-like method on ObjectProvider [SPR-14980] #19546 Provide computeIfAbsent-like method on ObjectProvider

Referenced from: commits e927cae

[spring-projects-issues]

Juergen Hoeller commented

I guess you could write this using Optional already:

Optional.ofNullable(webSessionManagerProvider.getIfAvailable()).ifPresent(
        (webSessionManager) -> builder.sessionManager(webSessionManager));

So effectively, this is about syntactic sugar for that kind of code? With ObjectProvider either providing an Optional return variant or, along the lines of your sketch, an ifAvailable(Consumer) convenience method directly?

[spring-projects-issues]

Juergen Hoeller commented

I've introduced corresponding ifAvailable(Consumer) and ifUnique(Consumer) variants, along the lines of Optional.ifPresent(Consumer).

[spring-projects-issues]

Andy Wilkinson commented

Thanks!