Using @Qualifier based on @Inject field CDI

Question

I'm having trouble with CDI conditional injection to use a kind of Strategy in EJB's injections.

My actual scenario is that:

public class someManagedBean {

    @Inject 
    @MyOwnQualifier(condition = someBean.getSomeCondition()) // not work because someBean is not already injected at this point
    private BeanInterface myEJB;

    @Inject
    SomeBean someBean;
}

@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface MyOwnQualifier {
    SomeCondition condition();
}

public class BeanInterfaceFactory {
    @Produces
    @MyOwnQualifier(condition = RoleCondition.ADMIN) 
    public BeanInterface getBeanInterfaceEJBImpl() {
        return new BeanInterfaceEJBImpl();
    }
}

public enum RoleCondition {
    ADMIN("ADMIN User");
}

Ok, scenario explained. Now the problem is that I need to get the value from someBean.getSomeCondition() that returns a RoleCondition, necessary for my @MyOwnQualifier. But at this time someBean is not already injected by CDI.

How I can make this line to work?

@Inject 
@MyOwnQualifier(condition = someBean.getSomeCondition()) // not work because some is not already injected at this point
private BeanInterface myEJB;

How is the right way to dynamically inject beans using qualifiers based on another injection's property value?

I don't really see how this can ever work since annotations are compile-time things, and someBean.getSomeCondition() evaluates at runtime. I'd more think you want to create a producer which can conditionally provide an instance. https://docs.jboss.org/weld/reference/1.0.0/en-US/html/producermethods.html — Gimby, Mar 07 '16 at 13:53
There is no such thing like `beforeConstruct` to evaluate some values before try to inject? — Johnny Willer, Mar 07 '16 at 13:55

score 4 · Accepted Answer · answered Mar 07 '16 at 14:34

4

Try this...

public class someManagedBean {

    @Inject 
    @MyOwnQualifier
    private BeanInterface myEJB;
}

@Qualifier
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.FIELD, ElementType.METHOD})
public @interface MyOwnQualifier {
    SomeCondition condition();
}

public class BeanInterfaceFactory {

    @Inject
    SomeBean someBean

    @Produces
    @MyOwnQualifier
    public BeanInterface getBeanInterfaceEJBImpl() {
        if(someBean.getCondition()) {         
            return new BeanInterfaceEJBImpl();
        } else {
           ....
        }
    }
}

public enum RoleCondition {
    ADMIN("ADMIN User");
}

answered Mar 07 '16 at 14:34

fantarama

862
6
14

Firstly, thank you for help. someBean for some reason is null at this time on factory `getBeanInterfaceEJBImpl` – Johnny Willer Mar 07 '16 at 14:46
if is null mean that BeanInterfaceFactory isn't a cdi bean, try add @Named. Wich discovery mode are you using in beans.xml ? – fantarama Mar 07 '16 at 14:50
Yeah, sorry for my ignorance haha, after lunch I will check if is everything alright, apparrently it will work. Thank you so much, you're the best :) – Johnny Willer Mar 07 '16 at 14:55
I'm glad to have helped you! ;-) – fantarama Mar 07 '16 at 14:57
Thanks man, it worked like a charm.. I just had to replace `new BeanInterfaceEJBImpl()` to `CDI.current().select(BeanInterfaceEJBImpl.class).get();` – Johnny Willer Mar 07 '16 at 17:41

Using @Qualifier based on @Inject field CDI

1 Answers1