[FIXED] javax.validation.ConstraintViolationException: name is null even though it shouldn't

Issue

I am creating a simple webapp with CRUD. However I am stuck with the create method, when ever I am creating a Host, I get ConstraintViolationException because the attribute name is null eventhough it shouldn't be null.

Host:

@Builder
@AllArgsConstructor(access = AccessLevel.PRIVATE)
@NoArgsConstructor(access = AccessLevel.PROTECTED)
@Entity
@Table(name = "hosts")
public class Host extends AbstractPersistable<Long> {

    @Getter
    @NotNull
    private String name;
    @Getter
    private String homepage;

    @Getter
    @ManyToMany(cascade = CascadeType.PERSIST)
    private Set<Show> shows;
}

HostDto:

public class HostDto {

    private String name;
    private String homepage;
    private Set<ShowDto> shows;
}

HostController:

@Controller
@RequestMapping(path = "/webapp/hosts")
public class HostController {

    private final HostService hostService;

    @RequestMapping("/new")
    public ModelAndView newHost() {

        ModelAndView mav = new ModelAndView("host-new");
        HostDto dto = new HostDto();
        mav.addObject("hostDto", dto);

        return mav;
    }

    @PostMapping("/save")
    public ModelAndView insertHost(@ModelAttribute("hostDto") HostDto hostDto) {

        hostService.insert(hostDto);
        return new ModelAndView("redirect:/");
    }
}

thymeleaf host-list:

<h1>Hosts</h1>
<a href="/webapp/hosts/new">Create new Host</a>

thymeleaf host-new:

<h1>Create new Host</h1>

<form action="#" th:action="@{/webapp/hosts/save}" th:object="${hostDto}" method="post">
    <input type="text" th:field="*{name}" id="name" placeholder="Name">
    <input type="text" th:field="*{homepage}" id="email" placeholder="homepage">
    <input type="submit" value="Add Host">
</form>

Exception:

javax.validation.ConstraintViolationException: Validation failed for classes [at.spengergasse.qaa18988.model.Host] during persist time for groups [javax.validation.groups.Default, ]
List of constraint violations:[
    ConstraintViolationImpl{interpolatedMessage='must not be null', propertyPath=name, rootBeanClass=class at.spengergasse.qaa18988.model.Host, messageTemplate='{javax.validation.constraints.NotNull.message}'}

HostService:

    public HostDto insert(HostDto host) {
        return Optional.ofNullable(host)
                .map(dto -> dto.toHost())
                .map(entity -> hostRepository.save(entity))
                .map(entity -> HostDto.valueOfHost(entity))
                .get();
    }

hostRepository extends the CrudRepository.

I believe that I've got the connection between HostController and Thymeleaf wrong, because I was debugging the insertHost() in HostController and all the attributes in hostDto were null.

Solution

Make sure you have @Setter above your class HostDto

Answered By - Naik
Answer Checked By - Pedro (JavaFixing Volunteer)