On Sun, Oct 31, 2021 at 9:56 AM 遗迹 <[email protected]> wrote:
> Are there any solution for this? In my case, I use it for OAS
> discriminator annotation. It looks like:
That thread is from 2017. Please start a new one with your question...
-+ Tatu +-
>
> ```kotlin
> class Pet(val pet: Discriminator("petType") OneOf2<Dog, Cat>)
> ```
>
> Without TYPE_USE annotation support, I can't get the discriminator
> information.
> Or are there any better choice to storage the information?
>
> Thank you.
> 在2017年12月29日星期五 UTC+8 上午5:08:49<Tatu Saloranta> 写道：
>
>> On Thu, Dec 28, 2017 at 2:16 AM, Bojan Tomic <[email protected]> wrote:
>> > Yes, TYPE_USE annotations and AnnotatedType were added in Java 8.
>> > As you noted, processing these can get quite hairy, but at least some
>> > support in Jackson would be very welcome.
>> > I am intimately familiar with the complexities involved, as I am the
>> > developer behind GeAnTyRef, a fork of GeTyRef (a library similar to
>> > ClassMate), that deeply supports working with AnnotatedTypes.
>>
>> Ah. Yes, your help here is appreciated and we could use your expertise.
>> Especially since you have an actual use case -- it's much easier to
>> add support for existing
>> use case, as opposed to expected or potential one.
>>
>> > I'm of the opinion Jackson would greatly gain in versatility if this
>> style
>> > of annotations was supported (as it makes it possible to convey
>> > (de)serialization hints on a very granular level).
>> > As I've mentioned, I'd be happy to contribute in order to get this
>> feature
>> > faster, if you'd be interested.
>>
>> Yes, I think that would make sense.
>>
>> As I said, `master` branch would be the the way to go at this point.
>> Code has been refactored quite a bit
>> since 2.9 in some places, but not so much wrt functionality for this,
>> I think. But code for 3.0 requires Java 8,
>> and 2 out of 3 modules (parameter names, Optional and other new types)
>> are part of `jackson-databind` now.
>>
>> -+ Tatu +-
>>
>>
>> >
>> >
>> >
>> > On Thursday, December 28, 2017 at 6:42:28 AM UTC+1, Tatu Saloranta
>> wrote:
>> >>
>> >> On Wed, Dec 27, 2017 at 9:33 AM, Bojan Tomic <[email protected]>
>> wrote:
>> >> > Just for the sake of experimentation, I've cobbled together the
>> >> > following
>> >> > wrapper class:
>> >> >
>> >> > class AnnotatedJavaType extends JavaType implements AnnotatedElement
>> {
>> >> >
>> >> > private final JavaType base;
>> >> > private final Annotation[] annotations;
>> >> >
>> >> > AnnotatedJavaType(JavaType base, Annotation[] annotations) { ... }
>> >> >
>> >> > //all methods simply delegate to this.base
>> >> > }
>> >> >
>> >> >
>> >> >
>> >> > And the corresponding TypeFactory wrapper:
>> >> >
>> >> > class AnnotatedTypeFactory {
>> >> >
>> >> > JavaType construct(AnnotatedType type, TypeFactory typeFactory) {
>> >> > if (type instanceof AnnotatedParameterizedType) {
>> >> > JavaType[] args = Arrays.stream(((AnnotatedParameterizedType)
>> >> > type).getAnnotatedActualTypeArguments())
>> >> > .map(arg -> fromJavaType(arg, typeFactory))
>> >> > .toArray(JavaType[]::new);
>> >> >
>> >> > TypeBindings bindings =
>> >> > TypeBindings.create(ClassUtils.getRawType(type.getType()), args);
>> >> >
>> >> > return new
>> >> > AnnotatedJavaType(typeFactory.constructType(type.getType(),
>> >> > bindings), type.getAnnotations());
>> >> > }
>> >> >
>> >> > //handle wildcards, arrays, variables in the similar fashion
>> >> >
>> >> > return new
>> >> > AnnotatedJavaType(typeFactory.constructType(type.getType()),
>> >> > type.getAnnotations());
>> >> > }
>> >> > }
>> >> >
>> >> > Amusingly enough, it works! I'd never keep it in my code base, but
>> it
>> >> > was an
>> >> > interesting experiment.
>> >> >
>> >> > If the functionality I'm after is impossible (and I really hope it
>> is
>> >> > not),
>> >> > would you be open to a contribution? I'd of course need some
>> >> > consultation/guidance on the approach, but would be happy to develop
>> it.
>> >>
>> >> As per my other note, this would need to be in Jackson 3.0 I think,
>> >> due to multiple reasons.
>> >>
>> >> I am bit hesitant to say much more since I really fear all complexity
>> >> that would come from trying
>> >> to create parallel annotation processing system. I can see some
>> >> benefits from type annotations,
>> >> but it wouldn't come for free, if we are talking about whole
>> >> AnnotationIntrospector style system.
>> >>
>> >> However: if the idea would be to do something simpler -- I don't
>> >> really see need for full AnnotationIntrospector
>> >> in this case, to be honest -- for example, simply keep track of
>> >> annotations for type, offer access... well,
>> >> that seems quite doable and useful. If so, `JavaType` could just have
>> >> `findAnnotation(Class<?> type)` method
>> >> or something?
>> >>
>> >> -+ Tatu +-
>> >>
>> >>
>> >>
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > On Wednesday, December 27, 2017 at 11:34:37 AM UTC+1, Bojan Tomic
>> wrote:
>> >> >>
>> >> >> I have a rather exotic use-case that I have to support. Types
>> annotated
>> >> >> with @Id need custom deserialization logic, e.g. the value should
>> be
>> >> >> Base64
>> >> >> decoded before deserializing it (not the only case).
>> >> >>
>> >> >> This means a type such as List<@Id Key> will be represented as a
>> list
>> >> >> of
>> >> >> Base64 Strings that I deserialize using my custom logic.
>> >> >>
>> >> >> I originally have an AnnotatedType that I convert to JavaType using
>> >> >> TypeFactory.constructType(annotatedType.getType()) prior to
>> >> >> deserialization,
>> >> >> which of course looses all the annotations.
>> >> >> Later, in my custom Deserializers instance, in its various
>> >> >> findXXXDeserializer methods, I have no way to find the correct
>> >> >> deserializer
>> >> >> as the annotations needed for the decision are gone...
>> >> >>
>> >> >> I was hoping the JDK8 module would have it's own TypeFactory-like
>> >> >> mechanism to construct JavaType subclasses that preserve the
>> >> >> annotations
>> >> >> from AnnotatedTypes (e.g.
>> >> >> AnnotatedTypeFactory.constructType(annotatedType)), but it doesn't
>> seem
>> >> >> to
>> >> >> be the case.
>> >> >>
>> >> >> Is there any way at all to implement what I'm after?
>> >> >
>> >> > --
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