Error on generating self link on pageable resource - spring

Question

Make a simple RestController
#RestController
public class Controloler
#Value
class MyData {
int value;
}
#GetMapping(value = "/datas", produces = MediaTypes.HAL_JSON_VALUE)
public PagedResources<Resource<MyData>> getMyData(PagedResourcesAssembler<MyData> assembler,
#RequestParam(required = false) String param,
#PageableDefault Pageable pageRequest)
{
MyData data = new MyData(1);
Page<MyData> page = new PageImpl<>(Collections.singletonList(data), pageRequest, 100);
Link selfLink = linkTo(methodOn(Controloler.class).getMyData(assembler, param, pageRequest)).withSelfRel();
return assembler.toResource(page, selfLink);
}
}
When I try to get page curl "http://localhost:8080/datas?param=12&page=2" have a problem with self link generation
{
"_embedded": {
"myDataList": [
{
"value": 1
}
]
},
"_links": {
"first": {
"href": "http://localhost:8080/datas?param=12&page=0&size=10"
},
"prev": {
"href": "http://localhost:8080/datas?param=12&page=1&size=10"
},
"self": {
"href": "http://localhost:8080/datas?param=12"
},
"next": {
"href": "http://localhost:8080/datas?param=12&page=3&size=10"
},
"last": {
"href": "http://localhost:8080/datas?param=12&page=9&size=10"
}
},
"page": {
"size": 10,
"totalElements": 100,
"totalPages": 10,
"number": 2
}
}
In my opinion, self link should be http://localhost:8080/datas?param=12&page=2&size=10.
Just now I can solve this problem without using pageable in arguments, just exact params page and size. But, I hope there is some solution with pageable
I've seen that in case of spring-data-rest self have a type of template. But I'd like to get the url I've requested

Answer 1

In my opinion, self link should be http://localhost:8080/datas?param=12&page=2&size=10.
I agree. In fact, it seems to be a bug. The most recent version of PagedResourcesAssembler does it differently:
Link selfLink = link.map(it -> it.withSelfRel())//
.orElseGet(() -> createLink(base, page.getPageable(), Link.REL_SELF));
(source)
Buggy versions of that class are doing this:
resources.add(createLink(base, null, Link.REL_SELF));
The createLink method is never passed the needed Pageable, but null as the second argument.
So, if you can't upgrade to the most recent version you can still work-around it:
Link selfLink = linkTo(methodOn(Controloler.class).getMyData(assembler, param, pageRequest)).withSelfRel();
UriComponentsBuilder builder = UriComponentsBuilder.fromUriString(selfLink.expand().getHref());
new HateoasPageableHandlerMethodArgumentResolver().enhance(builder, null, pageRequest);
Link newSelfLink = new Link(builder.build().toString());

Answer 2

According to Oliver's comment in an issue opened to address this, the self link should not contain template information, and this is not a bug.