[weld-dev] Fwd: Re[2]: How to make method injection when bean subclass is required in Weld?
Martin Kouba
mkouba at redhat.com
Tue Sep 5 02:43:50 EDT 2017
This is expected. See also assignability rules [1].
You need to use TypeLiteral [2]:
instance.select(new TypeLiteral<Temp<Foo>>() {})
Martin
[1]
https://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#assignable_parameters
[2]
https://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#annotationliteral_typeliteral
Dne 4.9.2017 v 20:47 Alex Sviridov napsal(a):
> Hi Martin,
>
> I am back with question about your solution. I have class Temp<Foo> and I
> create CDI bean using Instance.select(Temp.class).get().
>
> However, I get Caused by:
> org.jboss.weld.exceptions.UnsatisfiedResolutionException: WELD-001334:
> Unsatisfied dependencies for type Temp with qualifiers @Default.
>
> Could you say, how your solution can be used to create bean with generic?
>
> Best regards, Alex
>
>
>
> Четверг, 31 августа 2017, 12:50 +03:00 от Martin Kouba
> <mkouba at redhat.com>:
>
> 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 at redhat.com <mailto:manovotn at redhat.com>
> <mailto:manovotn at redhat.com <mailto:manovotn at 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 at mail.ru
> <mailto:ooo_saturn7 at mail.ru>
> > <mailto:ooo_saturn7 at mail.ru <mailto:ooo_saturn7 at mail.ru>>>
> > > To: "weld-dev" <weld-dev at lists.jboss.org
> <mailto:weld-dev at lists.jboss.org>
> > <mailto:weld-dev at lists.jboss.org <mailto:weld-dev at 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 at redhat.com <mailto:mkouba at redhat.com>
> <mailto:mkouba at redhat.com <mailto: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
> <mailto:ooo_saturn7 at mail.ru>
> > <mailto:ooo_saturn7 at mail.ru <mailto:ooo_saturn7 at mail.ru>> >
> > > >> To: "weld-dev" < weld-dev at lists.jboss.org
> <mailto:weld-dev at lists.jboss.org>
> > <mailto:weld-dev at lists.jboss.org <mailto: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 <mailto:weld-dev at lists.jboss.org>
> <mailto:weld-dev at lists.jboss.org <mailto:weld-dev at lists.jboss.org>>
> > > >> https://lists.jboss.org/mailman/listinfo/weld-dev
> > > > _______________________________________________
> > > > weld-dev mailing list
> > > > weld-dev at lists.jboss.org <mailto:weld-dev at lists.jboss.org>
> <mailto:weld-dev at lists.jboss.org <mailto:weld-dev at 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 at lists.jboss.org <mailto:weld-dev at lists.jboss.org>
> <mailto:weld-dev at lists.jboss.org <mailto:weld-dev at lists.jboss.org>>
> > > https://lists.jboss.org/mailman/listinfo/weld-dev
> >
> >
> >
> >
> ------------------------------------------------------------------------
> >
> > --
> > Alex Sviridov
>
> --
> Martin Kouba
> Senior Software Engineer
> Red Hat, Czech Republic
>
>
>
> --
> Alex Sviridov
--
Martin Kouba
Senior Software Engineer
Red Hat, Czech Republic
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