[cdi-dev] [JBoss JIRA] (CDI-552) Add support for injection, decorators and interceptors on "new-ed" objects

Ondrej Mihályi (JIRA) issues at jboss.org
Sat May 28 15:48:00 EDT 2016

    [ https://issues.jboss.org/browse/CDI-552?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13244396#comment-13244396 ] 

Ondrej Mihályi commented on CDI-552:

Isn't this what DeltaSpike provides already with {{BeanProvider.injectFields(myObject)}}? https://deltaspike.apache.org/documentation/core.html#_beanprovider
This method clearly only injects the dependencies, it does not invoke any lifecycle methods and does not add the object to any scope.

It would be useful to make this into the CDI spec, such as {{CDI.current().injectDependencies(Object o)}}.

It might also make sense to execute the lifecycle methods by {{CDI.current().invokePostConstruct(Object o)}} and {{invokePreDestroy(Object o}}, although they may be executed as directly on the object.

> Add support for injection, decorators and interceptors on "new-ed" objects
> --------------------------------------------------------------------------
>                 Key: CDI-552
>                 URL: https://issues.jboss.org/browse/CDI-552
>             Project: CDI Specification Issues
>          Issue Type: Feature Request
>          Components: Beans, Decorators, Interceptors, Resolution
>    Affects Versions: 2.0-EDR1
>            Reporter: Rogerio Liesenfeld
> The current CDI programming model is not friendly to object-oriented code or proper class design, and does not support true POJOs.
> With this I mean:
> 1) For object-oriented code, I need to be able to instantiate and use *stateful*, short-lived, objects, while still having @Inject fields in it. I shouldn't be forced to have a stateless (non-OO) class (ie, a [Transaction Script|http://martinfowler.com/eaaCatalog/transactionScript.html]).
> 2) Most classes in a business app are not meant to be used as subclasses, ie, they are not designed for extension; therefore, I should be able to make them {{final}} (see http://lcsd05.cs.tamu.edu/slides/keynote.pdf, page 26, or item 17 in the [book|http://www.amazon.com/Effective-Java-2nd-Joshua-Bloch/dp/0321356683]).
> 3) For a class to truly be a POJO, I must be able to make *full use* of the Java language when designing and implementing it; arbitrary constraints like "can't be final", "can't have final instance fields", "cannot be instantiated directly", etc. prevent it from being a "plain-old" Java object.
> Specifically, what I want is to be able to write the following in a JSF/CDI backing bean for a web UI:
> {code}
> MyBusinessService businessOp = new MyBusinessService(fieldFromUI1, fieldFromUI2, listWithMoreDataFromUI);
> businessOp.performSomeBusinessOperation(otherArgs);
> String result1 = businessOp.getResultXyz();
> List<result> moreResultData = businessOp.getFinalData();
> {code}
> ... while having MyBusinessService be a CDI bean containing one or more @Inject/@PersistenceContext fields (typically, an EntityManager and perhaps other service beans).
> Without this ability, application developers are forced to create procedural Transation Scripts (stateless service class, which tend to have low cohesion).
> For a CDI implementation to do this, it will need to use the java.lang.instrument API, like others tools (AspectJ, JBoss AOP, JBoss Byteman, JaCoCo, JMockit) already do.
> Also, for reference, the Spring framework already supports it for some time: http://docs.spring.io/spring/docs/3.0.0.M3/spring-framework-reference/html/ch08s08.html

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