Generics bounds too strict in RepresentationModelAssemblerSupport

[Bert-R]

With Spring Hateoas 0.25, we had code like this:

public class StatisticsResource extends Resource<StatisticsDto>
{
    :
}

public class StatisticsResourceAssembler
        extends ResourceAssemblerSupport<StatisticsDto, StatisticsResource>
{
    :
}

Now I'm migrating it to 1.0, like this:

public class StatisticsResource extends EntityModel<StatisticsDto>
{
    :
}

public class StatisticsResourceAssembler
        extends RepresentationModelAssemblerSupport<StatisticsDto, StatisticsResource>
{
    :
}

This however doesn't compile:

extends RepresentationModelAssemblerSupport<StatisticsDto, StatisticsResource>
                                                           ^
where D is a type-variable:
    D extends RepresentationModel<D> declared in class RepresentationModelAssemblerSupport

Any idea what's going wrong here?

P.S. I asked this on StackOverflow first and got the suggestion to use SimpleRepresentationModelAssembler, but that only works for this simple case. We have more complex cases too.

[odrotbohm]

This is glitch in our generics declarations. Will be fixed ASAP.

[Bert-R]

Thanks a lot for the quick fix!

[Bert-R]

I have tested with the snapshot build and this is fixed. Thanks!

[margfernan]

Please, I'm having the same issue with spring boot 2.2.2 and spring Hateoas v1. What is the version of Spring Hateoas with this issue solved?

[gregturn]

@margfernan If you use Spring Boot 2.3.0.BUILD-SNAPSHOT with <spring-hateoas.version> configured for 1.1.0.BUILD-SNAPSHOT, you can take it out for a spin.

I'm a little vague on whether or not 1.1.0.BUILD-SNAPSHOT works with current release of Boot 2.2.2.RELEASE or not.

[margfernan]

@odrotbohm and @gregturn thank you for your response but I tried with the version 1.1.0.BUILD-SNAPSHOT but the error still appears.
1)When is released the new version of the spring hateoas with this fix? or,
2)What version of the Spring Boot ( version > 2.x.x) recommend you to me to use Hateoas?
Last it, I attached a screenshot with the error.

Even, if I extend the assembler class to RepresentationModelAssemblerSupport, it happen the same issue.
Dependencies:
Spring Boot --> 2.2.2.RELEASE
groupId: org.springframework.boot -> artefactId : spring-boot-starter-hateoas (tried to 1.0.2.RELEASE and 1.1.0.BUILD-SNAPSHOT versions.)

Please, I need a urgent solution.
Best Regards
Martin

[odrotbohm]

As indicated by the error message you need to properly type ClientResourceDto to extends RepresentationModel<ClientResourceDto>.

The 1.1.0.BUILD-SNAPSHOTs should actually work with current Boot 2.2 as well. We could issue a first milestone of the former pretty soon if that helps. I'm afraid a GA release of Spring HATEOAS 1.1 is still a bit far out.

[Bert-R]

When I'm not mistaken, this is a compile-time fix that has no side-effects. Is it possible to backport this to 1.0.x and release it earlier?

[odrotbohm]

It changes API, which is why I was hesitant to back port it. On the other hand, IIUC it's completely unusable in the 1.0.x branch anyway, which means that there's nothing in there we can break even more than it already is broken, right?

[Bert-R]

Indeed, that's how I see it.

[odrotbohm]

Looks like we've already done this with #1126.

[Bert-R]

#1126 was included in 1.0.2. I've tested this on 1.0.2 and can confirm it is fixed.
@odrotbohm Thanks!

[margfernan]

As indicated by the error message you need to properly type ClientResourceDto to extends RepresentationModel<ClientResourceDto>.

The 1.1.0.BUILD-SNAPSHOTs should actually work with current Boot 2.2 as well. We could issue a first milestone of the former pretty soon if that helps. I'm afraid a GA release of Spring HATEOAS 1.1 is still a bit far out.

It works! Thanks a lot!!