Spring validation for Query parameters bound to collections in Controller methods wont fetch the correct values

Question

My PageSort Entity,

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class PageSort {
    private String sortBy;
    @SortValueConstraint
    private String sortDirection;
}

My ProjectPage Entity

@Data
@RequiredArgsConstructor
@Validated
public class ProjectPage {
    @Min(value = 1, message = "page number must be greater than zero")
    @IsNumberValidatorConstraint(message = "page number must be numeric")
    private String page = "1";

    @Min(value = 1, message = "page size must be greater than zero")
    @IsNumberValidatorConstraint(message = "page size must be numeric")
    private String size = "25";

    @Valid
    private List<PageSort> sort = Arrays.asList(PageSort.builder().sortBy("id").sortDirection("asc").build());
}

My RestController class

@Validated
@RestController
@RequestMapping("/api/projects")
public class ProjectController extends AbstractCRUDController<Project, ProjectPostDTO, ProjectPatchDTO, ProjectResponseDTO> {
    private ProjectApi projectApi;

    @GetMapping
    public ResponseEntity<ApiResponseDTO> getProjects(
            @Valid ProjectPage projectPage,
            @Valid ProjectSearchCriteria projectSearchCriteria){
        return new ResponseEntity<ApiResponseDTO>(null, HttpStatus.OK);
    }
}

I am trying to invoke the getProjects method as below

page and size parameter values are properly fetched inside the ProjectPage object but not the sort list in projectPage. But I tried using a single instance without the List and this worked perfectly.

Found a similar issue posted here Spring validation for RequestBody parameters bound to collections in Controller methods but did not solve the issue.

Any ideas on how to get this sorted?

Answer 1

RequestParam does not work on complex objects, only Strings. So you can have a List for all sortBy, and List for all sortDirection.

@GetMapping
    public ResponseEntity<ApiPageResponseDTO> getProjects(
            @Valid CustomPage page,
            @Valid @RequestParam(value = "sortBy", required = false) List<String> sortByList,
            @Valid @RequestParam(value = "sortDirection", required = false) @SortValueConstraint List<String> sortDirectionList,
            @Valid ProjectSearchCriteria projectSearchCriteria){
        final List<PageSort> sortList = new ArrayList<>();
        validateSortByAndSortDirectionsList(page, sortByList, sortDirectionList, sortList);
        ApiPageResponseDTO projectResponseDTO = this.projectApi.getProjects(page, projectSearchCriteria);
        return new ResponseEntity<ApiPageResponseDTO>(projectResponseDTO, HttpStatus.OK);
    }

Reference - Spring MVC @RequestParam a list of objects