在可分页资源上生成自链接时出错 [英] Error on generating self link on pageable resource

问题描述

制作一个简单的 RestController

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);
    }

}

当我尝试获取页面时 curl "http://localhost:8080/datas?param=12&page=2" 自链接生成有问题

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
  }
}

在我看来，自链接应该是 http://localhost:8080/datas?param=12&page=2&size=10.

In my opinion, self link should be http://localhost:8080/datas?param=12&page=2&size=10.

刚才我可以在不使用 pageable 参数的情况下解决这个问题，只需精确的参数页面和大小.但是，我希望有一些可分页的解决方案

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

我已经看到在 spring-data-rest self 的情况下有一种模板.但我想得到我请求的网址

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

推荐答案

在我看来，自链接应该是 http://localhost:8080/datas?param=12&page=2&size=10.

我同意.事实上，这似乎是一个错误.PagedResourcesAssembler 的最新版本做了不同的处理:

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));

(来源)

该类的 Buggy 版本正在这样做:

Buggy versions of that class are doing this:

resources.add(createLink(base, null, Link.REL_SELF));

createLink 方法永远不会传递所需的 Pageable，而是将 null 作为第二个参数传递.

The createLink method is never passed the needed Pageable, but null as the second argument.

因此，如果您无法升级到最新版本，您仍然可以解决这个问题:

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());

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