Четверг, 31 августа 2017, 12:50 +03:00 от Martin Kouba <mkouba(a)redhat.com&gt;: Hi Alex, 1) should work but looks a little bit cumbersome. WRT 2) you should avoid using BeanManager to create a bean instance whenever possible. And in this particular case, if SimpleFoo is @Dependent it wouldn't be destroyed correctly (@PreDestroy) when Parent or Child is destroyed. The following should also work (no need to have two Instance IPs): public class Parent {        @Inject        private Instance<SimpleFoo> fooInstance;        private SimpleFoo foo;        protected SimpleFoo newFoo() {              return fooInstance.get();        }        @PostConstruct        private void doPostConstruct() {            foo = newFoo();        }   }   public class Child extends Parent {        @Override        protected AdvancedFoo newFoo() {              return fooInstance.select(AdvancedFoo.class).get();        }   } Martin Dne 31.8.2017 v 11:07 Alex Sviridov napsal(a): > Hi Martin, > > > Could you comment the following solutions? > > 1) > public class Parent { > > @Inject > private Instance<SimpleFoo> fooInstance; > > private SimpleFoo foo; > > protected SimpleFoo newFoo() { > return fooInstance.get(); > } > > @PostConstruct > private void doPostConstruct() { > foo = newFoo(); > } > } > > public class Child extends Parent { > > @Inject > private Instance<AdvancedFoo> fooInstance; > > @Override > protected AdvancedFoo newFoo() { > return fooInstance.get(); > } > } > > > 2) > > public class Parent { > > @Inject > protected BeanManager beanManager; > > private SimpleFoo foo; > > protected SimpleFoo newFoo() { > SimpleFoo foo = constructing bean with BM; > return foo; > } > > @PostConstruct > private void doPostConstruct() { > foo = newFoo(); > } > } > > public class Child extends Parent { > > @Override > protected AdvancedFoo newFoo() { > AdvancedFoo foo = constructing bean with BM; > return foo; > } > } > > > Best regards, Alex > > Среда, 30 августа 2017, 10:51 +03:00 от Matej Novotny > < manovotn(a)redhat.com <mailto: manovotn(a)redhat.com >>: > > 1) If you inject Instance<T>, you still have the ambiguous > dependency issue for any class which does have a subclass. > E.g. from your sample: > > @Inject > Instance<SimpleFoo> instance; > > //within some method > instance.get(); -> this will blow up because you have two beans > which have SimpleFoo type (SimpleFoo and AdvancedFoo) > > 2) I don't understand what you mean by this. How does BM help here? > > > Sidenote: > You might want to try and use what Martin said - limiting the types > of a bean with @Typed(MyClass.Foo). > That way you have control over the bean types and can further > manupulate the injection. > Limit all your children to only the actual subclass type they have: > > @Dependent > @Typed(AdvancedFoo.class) > public class AdvancedFoo extends SimpleFoo { > // this ben now only has a bean of AdvancedFoo, e.g. it does not > fit into injection point for SimpleFoo > } > > And then override the initializer methods like this: > > @Dependent > public class Parent extends Child { > > @Inject > @Override > protected void setFoo(AdvancedFoo foo) { > this.foo = foo; // assuming foo is a protected field > } > } > > Matej > > > ----- Original Message ----- > > From: "Alex Sviridov" < ooo_saturn7(a)mail.ru > <mailto: ooo_saturn7(a)mail.ru >> > > To: "weld-dev" < weld-dev(a)lists.jboss.org > <mailto: weld-dev(a)lists.jboss.org >> > > Sent: Tuesday, August 29, 2017 8:54:47 PM > > Subject: Re: [weld-dev] How to make method injection when bean > subclass is required in Weld? > > > > I thought here, and would like to share my ideas hoping to get > comments from > > more experienced people. > > > > First of all I came to conclusion that CDI works badly with cases > when we > > need > > to change field values in super classes. If there is a lot of > inheritance as > > in my case: > > ParentA, ChildA0, ChildA1.., ParentB, ChildB0, ChildB1..,... then > situation > > is > > becoming very bad. Maybe in future there will be other solutions > in CDI > > specs. > > > > I found two additional ways that can be used. 1) Inject not beans but > > instances, > > + method SimpleFoo newFoo {return Instance<SimpleFoo>.get} + > overriding. > > 2) Inject BeanManager + method SimpleFoo newFoo() {beanManager...} + > > overriding. > > > > Maybe such ways can be named lazy/postponed initialization with > overriding > > support.... > > > > Best regards, Alex > > > > > > > > > > Вторник, 29 августа 2017, 18:22 +03:00 от Martin Kouba > < mkouba(a)redhat.com <mailto: mkouba(a)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(a)mail.ru > <mailto: ooo_saturn7(a)mail.ru > > > > >> To: "weld-dev" < weld-dev(a)lists.jboss.org > <mailto: weld-dev(a)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(a)lists.jboss.org <mailto: weld-dev(a)lists.jboss.org > > > >> https://lists.jboss.org/mailman/listinfo/weld-dev > > > _______________________________________________ > > > weld-dev mailing list > > > weld-dev(a)lists.jboss.org <mailto: weld-dev(a)lists.jboss.org > > > > https://lists.jboss.org/mailman/listinfo/weld-dev > > > > > > > -- > > Martin Kouba > > Senior Software Engineer > > Red Hat, Czech Republic > > > > > > _______________________________________________ > > weld-dev mailing list > > weld-dev(a)lists.jboss.org <mailto: weld-dev(a)lists.jboss.org > > > https://lists.jboss.org/mailman/listinfo/weld-dev > > > > ------------------------------------------------------------------------ > > -- > Alex Sviridov -- Martin Kouba Senior Software Engineer Red Hat, Czech Republic