[cdi-dev] [JBoss JIRA] (CDI-414) Support for "self" injection

[arjan tijms (JIRA)]

    [ https://issues.jboss.org/browse/CDI-414?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12994111#comment-12994111 ] 

arjan tijms commented on CDI-414:
---------------------------------

{quote}Which scope are you using?{quote}

For the specific case as given in the original example: no explicit scope. Just a {{stateless}} EJB into itself:

{code}
@Stateless
public class Foo {

    @EJB
    private Foo self;

    // ...
}
{code}

As stated, this works when using {{@EJB}}, but does not work when using {{@Inject}}, so for this particular use case injecting via {{@EJB}} is more powerful in a way, since it's capable of doing a kind of injection that CDI currently can not do.

Maybe another solution is to define a CDI scope (or something else) that closely mimics EJB's {{@Stateless}} and for which self-injection is explicitly supported.

> Support for "self" injection
> ----------------------------
>
>                 Key: CDI-414
>                 URL: https://issues.jboss.org/browse/CDI-414
>             Project: CDI Specification Issues
>          Issue Type: Bug
>          Components: Resolution
>            Reporter: arjan tijms
>
> Many features of CDI and EJB work by means of a proxy that intercepts calls and adds 'aspects'. In Java it's however not possible to decorate the {{this}} pointer, so methods called on the same bean instance from within a method in the bean do not get their 'aspects' applied.
> This is a well known limitation, but in EJB it's possible to work around this by injecting a bean into itself. E.g.
> {code}
> @Stateless
> public class Foo {
>     @EJB
>     private Foo self;
>     // ...
> }
> {code}
> Also see http://adam-bien.com/roller/abien/entry/how_to_self_invoke_ejb
> Unfortunately using CDI and {{@Inject}} this doesn't work. Weld for instance fails the deployment and logs:
> {noformat}
> WELD-001443 Pseudo scoped bean has circular dependencies.
> {noformat}
> See also: http://adam-bien.com/roller/abien/entry/inject_vs_ejb
> Although there are workarounds, it would be great if {{@Inject}} in combination with CDI could support self injection as well.
> With that projects migrating from {{@EJB}} to {{@Inject}} can do so more easily and the capability can be convenient for new projects as well (e.g. calling two separate {{@Transactional}} methods from a single method without being required to create a new bean).



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