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

[Mark Struberg]

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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