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

[Jozef Hartinger]

Other than this I am not aware of any other way of suppressing CDI/Weld 
injection. Since you have control over the producer methods you could 
perhaps implement this on the JBeret side using thread locals to pass 
the injected instance/default values around?

On 03/09/2015 03:43 PM, Cheng Fang wrote:
> (I just subscribed to cdi-dev, and tried to post to it several times, 
> but bounced back, so send to you)
>
> Thanks, Jozef.
>
> I'm mostly concerned with user-supplied default field values.  For JVM 
> default field values, we currently just let CDI inject null, or 
> primitive defaults to it.
>
> I just tried your suggestion, adding the following method to 
> BatchCDIExtension class:
> public<T>voidprocessAnnotatedType(@ObservesProcessAnnotatedType<T> pat,
>                                       BeanManager beanManager) {...}
>
> and found batch properties are not yet available when it is called.  This method seems to be called during scanning, which is
> pretty early stage.
>
> Cheng
>
> On 3/9/15 2:39 AM, Jozef Hartinger wrote:
>> You can actually work around by listening to ProcessAnnotatedType and 
>> removing the @Inject annotation from injection points for which there 
>> is no value to inject. Is the set of defined key-value pairs known at 
>> the time when the CDI extension is called?
>>
>> Jozef
>>
>> On 03/09/2015 07:25 AM, Jozef Hartinger wrote:
>>> 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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>>
>

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