Why not receiving pageable details in spring boot?

Question

I am working in a spring boot project. I am required to return a list with pagination. Currently I can choose the page and size in parameters but i am not receiving page details like:

"last": false,
"totalElements": 20,
"totalPages": 7,
"size": 3,
"number": 0,
"sort": null,
"first": true,
"numberOfElements": 3

I am just receiving a normal response without that. I think I need to change method response type to ResponseEntity or Resources. Any ideas?

Controller:

public List<PostOutputDTO> getTopicPosts(@PathVariable("id") UUID topicId, Pageable pageable) {
   return postService.getActivePosts(topicId, pageable);

Service:

 public List<PostOutputDTO> getActivePosts(UUID topicId, Pageable pageable) throws AccessDeniedException {
    Topic topic = topicRepo.findByIdAndDeactivatedAtIsNull(topicId).orElseThrow(() -> new EntityNotFoundException("This topic doesn't exist."));
    if (topic.getType() != TopicType.GLOBAL) {
        throw new AccessDeniedException("This is not a global topic.");
    }
    return postAssembler.toResources(postRepo.findPostsByTopicAndDeactivatedAtIsNull(topic, pageable));
}

Assembler:

@Service
public class PostAssembler extends ResourceAssemblerSupport<Post, PostOutputDTO> {

    @Autowired
    private ForumUserAssembler forumUserAssembler;

    @Autowired
    private TopicAssembler topicAssembler;

    @Autowired
    private ContentRepo contentRepo;

    public PostAssembler() {
        super(PostController.class, PostOutputDTO.class);
    }

    public PostOutputDTO toResource(Post post) {
        return PostOutputDTO.builder()
                .uuid(post.getId())
                .topic(topicAssembler.toResource(post.getTopic()))
                .text(contentRepo.findByPostAndDeactivatedAtIsNull(post).orElseThrow(() -> new EntityNotFoundException("This post doesn’t have content")).getText())
                .createdAt(post.getCreatedAt())
                .createdBy(forumUserAssembler.toResource(post.getCreatedBy()))
                .build();
    }
}

Repository:

@Repository
public interface TopicRepo extends JpaRepository<Topic, UUID> {

    Page<Topic> findAllByTypeAndDeactivatedAtIsNull(TopicType topicType, Pageable pageable);

}

Andrew Tobilko · Accepted Answer · 2018-10-03T17:38:13.897

3

Adjust the return type to Page<PostOutputDTO> instead of List<PostOutputDTO>.

The easiest way to convert a List<PostOutputDTO> to a Page<PostOutputDTO> is

public Page<PostOutputDTO> getTopicPosts(@PathVariable("id") UUID topicId, Pageable pageable) {
    return new PageImpl<>(postService.getActivePosts(topicId, pageable));
}

Update:

I still don't see the whole picture, but I hope the repository methods return Page instances,

Page<Post> findPostsByTopicAndDeactivatedAtIsNull(...);
Page<Topic> findAllByTypeAndDeactivatedAtIsNull(...);

so the problem comes from PostAssembler#toResources which returns a List, which we inaccurately transform into a Page back.

If I get you correctly, you are utilising ResourceAssemblerSupport to map an Iterable<Post> (more precisely, a Page<Post>) to a List<PostOutputDTO>.

What I am suggesting is to not use PostAssembler#toResources and stick to PostAssembler#toResource and Page#map:

postRepo.findPostsByTopicAndDeactivatedAtIsNull(topic, pageable)
        .map(postAssembler::toResource);

edited Oct 03 '18 at 17:38

answered Oct 03 '18 at 14:15

Andrew Tobilko

48,120
14
91
142

1

Worked! Thank you! – Chefk5 Oct 03 '18 at 14:18
@Chefk5 happy to help – Andrew Tobilko Oct 03 '18 at 14:21
Do you have an idea why "totalElements" does not show all the elements. It shows only in current page – Chefk5 Oct 03 '18 at 14:26
@Chefk5 look here: https://stackoverflow.com/questions/26720768/spring-data-pageimpl-not-returning-page-with-the-correct-size – Andrew Tobilko Oct 03 '18 at 14:34
@Chefk5 you may not use `PageImpl` but return a `Page` directly from the repository – Andrew Tobilko Oct 03 '18 at 14:36
@Chefk5 it's hard to say because I don't know what your repository returns and what `postAssembler.toResources` does – Andrew Tobilko Oct 03 '18 at 14:37
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/181230/discussion-between-chefk5-and-andrew-tobilko). – Chefk5 Oct 03 '18 at 14:54
I didnt use the assembler at all and it worked..I tried that in a mock project. Will see tmrw if it works like that...because the issue is in the assembler as you pointed. Thanks alot for your time – Chefk5 Oct 03 '18 at 17:48

score 1 · Answer 2 · answered Oct 03 '18 at 14:42

1

You must return Interface Page from spring:

A page is a sublist of a list of objects. It allows gain information about the position of it in the containing.

See the example:

public Page<PostOutputDTO>  getActivePosts(UUID topicId, Pageable pageable) {

    Page<PostOutputDTO>  list=postService.getActivePosts(topicId, pageable);

      return  list;

}

for more info see the reference

answered Oct 03 '18 at 14:42

Fernix

361
3
10

its an interface Page – Fernix Oct 03 '18 at 16:27
you don't need to return an implementation new PageImpl<> because your repository must return a Pageable like this : public interface ExampleRepository extends PagingAndSortingRepository { public Page findAllExampleObjects( Pageable pageable);} – Fernix Oct 03 '18 at 16:32
ok..now i have a problem in last line of service with the assembler...eventhough i changed return type to page – Chefk5 Oct 03 '18 at 17:03

Why not receiving pageable details in spring boot?

2 Answers2