[weld-dev] How to make method injection when bean subclass is required in Weld?

[Alex Sviridov]

Hi Martin, hi Matej,

Thank you very much for your suggestions. 

Best regards, Alex


>Вторник, 29 августа 2017, 18:22 +03:00 от Martin Kouba <mkouba at redhat.com>:
>
>Hi Alex,
>
>that's an interesting question. Indeed, qualifiers are the way to go if 
>you need to keep the method signature.
>
>Another way could be to override the setFoo() method so that the Child 
>initializer is ignored and add a new method to inject AdvancedFoo:
>
>@Override
>protected void setFoo(SimpleFoo foo) { // Do nothing }
>
>@Inject
>void setAdvancedFoo(AdvancedFoo foo) {
>   super.setFoo(foo);
>}
>
>However, note that right now there are the following beans:
>
>SimpleFoo with bean types Object, SimpleFoo
>AdvancedFoo -> Object, SimpleFoo, AdvancedFoo
>
>So if you do @Inject SimpleFoo you get ambiguous dependency exception 
>because both SimpleFoo and AdvancedFoo are eligible for injection.
>
>To resolve this you need to use qualifiers or restrict the bean types of 
>AdvancedFoo:
>
>@Typed(AdvancedFoo.class)
>class AdvancedFoo extends SimpleFoo {}
>
>HTH
>
>Martin
>
>
>Dne 29.8.2017 v 15:09 Matej Novotny napsal(a):
>> Hi Alex,
>> 
>> no need to be sorry, you have come to the right place :)
>> As for your question, the simplest thing is probably to use qualifiers.
>> 
>> Create your own like this:
>> 
>> @Qualifier
>> @Retention(RetentionPolicy.RUNTIME)
>> @Target({ ElementType.TYPE, ElementType.PARAMETER, ElementType.FIELD, ElementType.METHOD })
>> public @interface MyQualifier {}
>> 
>> 
>> And then change your AdvancedFoo class to use the qualifier:
>> 
>> @Dependent
>> @MyQualifier
>> public class AdvancedFoo extends SimpleFoo {
>> }
>> 
>> And accordingly, the init method which uses injection should then look like this:
>> 
>> @Dependent
>> public class Parent extends Child {
>> 
>>    @Inject
>>    @Override
>>    protected void setFoo(@MyQualifier SimpleFoo foo) {
>>      super.setFoo(foo);
>>    }
>> }
>> 
>> Does this answer your question?
>> 
>> Matej
>> 
>> ----- Original Message -----
>>> From: "Alex Sviridov" < ooo_saturn7 at mail.ru >
>>> To: "weld-dev" < weld-dev at lists.jboss.org >
>>> Sent: Tuesday, August 29, 2017 1:46:23 PM
>>> Subject: [weld-dev] How to make method injection when bean subclass is required in Weld?
>>>
>>> Hi all,
>>>
>>> I am really sorry for writing to this mailing list, but I checked all user
>>> forums and chats and saw that they are very old.
>>>
>>> I would be very thankful if someone gives suggestion for solving the
>>> following problem.
>>> I have a child and parent class. Child has SimpleFoo, Parent needs Advaced
>>> foo. So,
>>>
>>> @Dependent
>>> public class SimpleFoo {
>>> }
>>>
>>> @Dependent
>>> public class AdvancedFoo extends SimpleFoo {
>>> }
>>>
>>> @Dependent
>>> public class Child {
>>>
>>> private SimpleFoo foo;
>>>
>>> @Inject
>>> protected void setFoo(SimpleFoo foo) {
>>> this.foo = foo;
>>> }
>>> }
>>>
>>> @Dependent
>>> public class Parent extends Child {
>>>
>>> @Inject
>>> @Override
>>> protected void setFoo(SimpleFoo foo) { //How to inject here AdvancedFoo?
>>> super.setFoo(foo);
>>> }
>>> }
>>>
>>> How to inject in Parent AdvancedFoo? I know that I can do it via constructor
>>> injection
>>> but I need method injection. How to do it? Can it be done without using names
>>> (like MyBean1)
>>> but only using classes (AdvancedFoo)?
>>>
>>> Best regards, Alex
>>>
>>>
>>>
>>>
>>>
>>> --
>>> Alex Sviridov
>>>
>>> _______________________________________________
>>> weld-dev mailing list
>>>  weld-dev at lists.jboss.org
>>>  https://lists.jboss.org/mailman/listinfo/weld-dev
>> _______________________________________________
>> weld-dev mailing list
>>  weld-dev at lists.jboss.org
>>  https://lists.jboss.org/mailman/listinfo/weld-dev
>> 
>
>-- 
>Martin Kouba
>Senior Software Engineer
>Red Hat, Czech Republic

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