[weld-dev] [cdi-dev] How to skip CDI injection if a property is not configured in batch application?

[Jozef Hartinger]

Moving the thread back to weld-dev

On 03/09/2015 10:32 AM, Jozef Hartinger wrote:
> How do you obtain the current value of a field from an InjectionPoint?
> Do you use proprietary APIs for that?
>
> Jozef
>
> On 03/09/2015 09:52 AM, Mark Struberg wrote:
>> There is an easy trick though which we do at BatchEE:
>> The producer is @Dependent. So you can simply inject the InjectionPoint and inspect the current value in case it is not yet set.
>>
>> LieGrue,
>> strub
>>
>>
>>> Am 09.03.2015 um 07:25 schrieb Jozef Hartinger <jharting at redhat.com>:
>>>
>>> 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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