How to register bean programatically in Quarkus?

Question

I am trying to find a way how to programatically create bean in quarkus DI, but without success. Is it possible in this framework? It seems that BeanManager does not implement the needed method yet.

Answer 1

First, we should clarify what "programatically create bean" exactly means.

But first of all, we should define what "bean" means. In CDI, we talk about beans in two meanings:

1. Component metadata - this one describes the component attributes and how a component instance is created; the SPI is javax.enterprise.inject.spi.Bean
2. Component instance - the real instance used in application; in the spec we call it "contextual reference".

The metadata is usually derived from the application classes. Such metadata are "backed by a class". By "backed by a class" I mean all the kinds described in the spec. That is class beans, producer methods and producer fields.

Now, if you want to programatically obtain a component instance (option 2), you can:

1. Inject javax.enterprise.inject.Instance; see for example the Weld docs
2. Make use of CDI.current().select(Foo.class).get()
3. Make use of quarkus-specific Arc.container().instance(Foo.class).get()

However, if you want to add/register a component metadata that is not backed by a class (option 2), you need to add an extension that makes use of quarkus-specific SPIs, such as BeanRegistrar.

Answer 2

If you are looking for Quarkus equivalent of Spring @Configuration then you want "bean producer" (as mentioned in comments above)

Here is an example(koltin) of how to manually register a clock:

import java.time.Clock
import javax.enterprise.context.ApplicationScoped
import javax.enterprise.inject.Produces

@ApplicationScoped
class AppConfig {

   @Produces
   @ApplicationScoped
   fun utcClock(): Clock {
       return Clock.systemUTC()
   }  
}

• @Produces is actually not required if method is already annotated with @ApplicationScoped
• @ApplicationScoped at class level of AppConfig is also not required

Although, I find those extra annotations useful, especially if are used to Spring.