Dowemo


Question:

How can I inject a dependency like @EJB, @PersistenceContext, @Inject, @AutoWired, etc in a @FacesValidator? In my specific case I need to inject a Spring managed bean via @AutoWired:

@FacesValidator("emailExistValidator")


public class EmailExistValidator implements Validator {



    @Autowired


    private UserDao userDao;



    // ...


}


However, it didn't get injected and it remains null, resulting in java.lang.NullPointerException. It seems that @EJB, @PersistenceContext and @Inject also doesn't work.

How do I inject a service dependency in my validator so that I can access the DB?


Best Answer:


The @FacesValidator isn't managed by the injection container. You need to make it a managed bean. Use Spring's @Component, CDI's @Named or JSF's @ManagedBean instead of @FacesValidator in order to make it a managed bean and thus eligible for dependency injection.

E.g., assuming that you want to use JSF's @ManagedBean:

@ManagedBean


@RequestScoped


public class EmailExistValidator implements Validator {


    // ...


}


You also need to reference it as a managed bean by #{name} in EL instead of as a validator ID in hardcoded string. Thus, so

<h:inputText ... validator="#{emailExistValidator.validate}" />


or

<f:validator binding="#{emailExistValidator}" />


instead of

<h:inputText ... validator="emailExistValidator" />


or

<f:validator validatorId="emailExistValidator" />


This is indeed awkward. The JSF guys have confirmed this embarrassing oversight and they will make the @FacesValidator (and @FacesConverter) an eligible injection target in upcoming JSF 2.2 2.3, see also JSF spec issue 763. For EJBs there's a workaround by manually grabbing it from JNDI, see also Getting an @EJB in @FacesConverter and @FacesValidator. If you happen to use the CDI extension MyFaces CODI, then you can also solve it by putting @Advanced annotation on the class.

See also:

Update: if you happen to use JSF utility library OmniFaces, since version 1.6 is adds transparent support for using @Inject and @EJB in a @FacesValidator class without any additional configuration or annotations. See also the CDI @FacesValidator showcase example.




Copyright © 2011 Dowemo All rights reserved.    Creative Commons   AboutUs