support conditional bean

Description

I want to enable or disable Kafka consumer based on a runtime property, currently @IfBuildProperty doesn’t support runtime property.

https://docs.micronaut.io/latest/guide/#conditionalBeans

This @Requires annotation looks good:

@ApplicationScoped
@Requires(property="my.consumer.enabled", value="true")
public class MyConsumer {
    @Incoming("topic")
    public void consume(Xxx x) {
    }
}

Implementation ideas

Implementation something like Micronaut @Requires.

[Dieken]

Sorry I don’t get your point. When I say “@Requires annotation is ignored at build time”, I mean all beans are required at build time, just like there is no @Requires annotation at all, so Quarkus can do fully validation at build time.

That won’t work. Imagine you have a bean Foo extends Bar with @Requires(property="my.consumer.enabled", value="true") and a bean Baz extends Bar with @Requires(property="my.consumer.enabled", value="false"). If you ignore @Requires at build time and perform the full validation then @Inject Bar would fail with ambiguous dependency error - there are multiple beans that satisfy this injection point.

Very valid point👍🏻 I can’t figure out a build time solution now except we explicitly forbidden this usage😄

According to native-image-pre-boot, it is an optimization for Quarkus framework, it won’t be affected if @requires isn’t used by Quarkus framework.

The CDI container is used for both framework beans and application beans. The condition if (required(objA_id)) is an oversimplification that does not reflect the real behavior.

Understand, detail is the devil 😃

[mkouba]

Sorry I don’t get your point. When I say “@Requires annotation is ignored at build time”, I mean all beans are required at build time, just like there is no @Requires annotation at all, so Quarkus can do fully validation at build time.

That won’t work. Imagine you have a bean Foo extends Bar with @Requires(property="my.consumer.enabled", value="true") and a bean Baz extends Bar with @Requires(property="my.consumer.enabled", value="false"). If you ignore @Requires at build time and perform the full validation then @Inject Bar would fail with ambiguous dependency error - there are multiple beans that satisfy this injection point.

According to native-image-pre-boot, it is an optimization for Quarkus framework, it won’t be affected if @requires isn’t used by Quarkus framework.

The CDI container is used for both framework beans and application beans. The condition if (required(objA_id)) is an oversimplification that does not reflect the real behavior.