Adding weld-dev.

Hi Cheng,

by defining a producer method you are basically saying "I am able to supply an object for this given type/qualifier combination". There is not way to opt out of it at runtime. Are you concerned about the JVM default values or the default values a user has provided?

Jozef

On 03/07/2015 05:54 PM, Cheng Fang wrote:

Hi Jozef,

I'm having a question in using CDI injection in project JBeret (batch impl project), and would appreciate any help from you.

A batch application (in Java SE or EE) can inject configured batch properties into batch artifact classes:

@Inject
@javax.batch.api.BatchProperty(name = "batchPropName")
String batchPropName = "default name";

The property value comes from job.xml, which is the batch job definition descriptor file:

<batchlet ref="batchlet1">
        <properties>
               <property name="batchPropName" value="configured name"/>
        </properties>
...

When "batchPropName" property is not configured in job.xml, the injection should not happen, and whatever java default field value should be preserved for batchPropName field. 

With our current batch CDI extension [1] and producer bean [2], it injects a null value into this field, overwriting the java default value, when the target batch property is not present.

How to signal to Weld to skip performing the injection for those injection targets?  Ideally, I hope it can be done from within producer methods, which is the place we retrieve batch properties and know whether they exist or not.

I think this is also how Java EE field injection works.  How do we handle it in EE, and is it something I can mirror?

Thanks,
Cheng

[1] https://github.com/jberet/jsr352/blob/master/jberet-core/src/main/java/org/jberet/creation/BatchCDIExtension.java

[2] https://github.com/jberet/jsr352/blob/master/jberet-core/src/main/java/org/jberet/creation/BatchBeanProducer.java

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