My controller endpoint has a method which cannot be found:

@GetMapping("")
public ResponseEntity<PagedModel<PostModel>> findAll(
        @PageableDefault(sort = { "orderedOn" }, direction = Sort.Direction.ASC) Pageable pageable, Sort sort,
        PagedResourcesAssembler<PostModel> pagedResourcesAssembler, UriComponentsBuilder builder) {
    sort = RESTUtils.stripColumnsFromSorting(sort, nonSortableColumns);
    postService.addSortToPageable(pageable, sort);
    Page<Post> posts = postService.findAll(pageable);
    PagedModel<PostModel> pagedPostModels = pagedResourcesAssembler.toModel(posts, postModelAssembler);
    UriComponentsBuilder uriComponentsBuilder = builder.path(RESTUtils.SLASH);
    modelService.addPageableToUri(uriComponentsBuilder, pageable);
    HttpHeaders responseHeaders = new HttpHeaders();
    responseHeaders.setLocation(uriComponentsBuilder.buildAndExpand().toUri());
    return ResponseEntity.status(HttpStatus.OK).headers(responseHeaders).body(pagedPostModels);
}

The full error message is: The method toModel(Page<PostModel>, Link) in the type PagedResourcesAssembler<PostModel> is not applicable for the arguments (Page<Post>, PostModelAssembler)

The IDE contextual documentation shows the methods:

public <R extends RepresentationModel<?>> PagedModel<R> toModel(Page<T> page,
        RepresentationModelAssembler<T, R> assembler) {
    return createModel(page, assembler, Optional.empty());
}

public PagedModel<EntityModel<T>> toModel(Page<T> page, Link selfLink) {
    return toModel(page, EntityModel::of, selfLink);
}

It feels like it cannot find the first method and ends up defaulting on the second one.

The assembler class:

import static org.springframework.hateoas.server.mvc.WebMvcLinkBuilder.linkTo;
import static org.springframework.hateoas.server.mvc.WebMvcLinkBuilder.methodOn;

import org.springframework.beans.BeanUtils;
import org.springframework.hateoas.CollectionModel;
import org.springframework.hateoas.server.mvc.RepresentationModelAssemblerSupport;
import org.springframework.lang.NonNull;
import org.springframework.stereotype.Component;

import com.thalasoft.post.PostController;
import com.thalasoft.post.entity.Post;
import com.thalasoft.post.model.PostModel;
import com.thalasoft.post.service.ModelService;

@Component
public class PostModelAssembler extends RepresentationModelAssemblerSupport<Post, PostModel> {

    private final ModelService modelService;

    public PostModelAssembler(ModelService postService) {
        super(PostController.class, PostModel.class);
        this.modelService = postService;
    }

    @NonNull
    @Override
    public PostModel toModel(@NonNull Post entity) {
        PostModel model = createModelWithId(entity.getId(), entity);
        model.add(linkTo(methodOn(PostController.class)
                .findById(entity.getId()))
                .withSelfRel());
        BeanUtils.copyProperties(modelService.fromPost(entity), model);
        return model;
    }

    @NonNull
    @Override
    public CollectionModel<PostModel> toCollectionModel(@NonNull Iterable<? extends Post> entities) {
        CollectionModel<PostModel> postModels = super.toCollectionModel(entities);
        postModels.add(linkTo(methodOn(PostController.class).findAll()).withSelfRel());
        return postModels;
    }
}

The Post entity:

@Getter
@Setter
@Builder
@NoArgsConstructor
@AllArgsConstructor
@ToString
@Entity
@Table(name = "post")
public class Post extends AbstractEntity {

    @Column(name = "user_id", nullable = true)
    private Long userId;

    @Column(nullable = false)
    private String title;

    @Column(nullable = false)
    private String body;

    @NaturalId
    @Column(nullable = false, unique = true)
    private String isbn;

}

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
@ToString
@MappedSuperclass
public abstract class AbstractEntity implements Serializable {

    protected static final long serialVersionUID = 1L;

    @Id
    // Compatible with H2, MySQL, PostgreSQL, Oracle
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_generator")
    @Column(name = "id", updatable = false, nullable = false)
    private Long id;

    @Version
    @Column(nullable = false)
    private Integer version;

    @CreationTimestamp
    private LocalDateTime createdOn;

    @UpdateTimestamp
    private LocalDateTime updatedOn;

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }

        if (!(o instanceof AbstractEntity)) {
            return false;
        }

        AbstractEntity other = (AbstractEntity) o;

        return id != null && id.equals(other.getId());
    }

    // The equals() and hashCode() methods must behave consistently across all state
    // transitions of the entity
    // The hash code must remain the same accross all states of the persistence life
    // cycle
    // Thus the object address cannot be the hash code as a new object is created
    // after the entity is persisted
    // And the entity id cannot be the hash code as an entity not yet persisted has
    // no id and gets one after being persisted
    // As the hash code should always return the same value, the class name is used
    // as the hash code
    // See
    // https://vladmihalcea.com/how-to-implement-equals-and-hashcode-using-the-jpa-entity-identifier/
    @Override
    public int hashCode() {
        return getClass().hashCode();
    }
}

The PostModel model:

@Data
@Builder
@NoArgsConstructor
@AllArgsConstructor
@EqualsAndHashCode(callSuper = false)
@JsonRootName(value = "post")
@Relation(collectionRelation = "posts")
@JsonInclude(Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
public class PostModel extends RepresentationModel<PostModel> {

    @Id
    private Long id;

    private Long userId;

    @NotEmpty
    private String title;

    @NotEmpty
    private String body;

    @NotEmpty
    private String isbn;

    @Version
    private Integer version;

}

I’m on SpringBoot 3.3.0 and Java 21