Java 使用Spring数据REST管理枚举

我有一个关于SpringBoot1.5.7、SpringDataREST、Hibernate、HATEOAS和SpringValidation的项目

我真的很难管理枚举。我需要两件简单的事情：

获取特定枚举的项列表（HTTP REST）

将枚举作为参数发送到HTTP REST调用中

我使用的是SpringDataREST，所以应该从中做很多工作

我的枚举是基本的，如：

public enum TransitCertificateStatus {
    PENDING, USED, CANCELED, ARCHIVED
}

此枚举用于bean：

@Entity
@EntityListeners(TransitCertificateListener.class)
public class TransitCertificate extends AbstractEntity {
    private static final long serialVersionUID = 5978999252424024545L;

    @NotNull(message = "{NotNull.transitcertificate.status}")
    @Column(nullable = false)
    @Enumerated(EnumType.STRING)
    private TransitCertificateStatus status = TransitCertificateStatus.PENDING;

要向客户端公开枚举项，我创建了一个自定义控制器：

@Api(tags = "TransitCertificate Entity")
@RepositoryRestController
@RequestMapping(path = "/api/v1/transitCertificates")
public class TransitCertificateController {
    private Logger log = LogManager.getLogger();

@RequestMapping(method = RequestMethod.GET, path = "/states", produces = "application/json")
    public @ResponseBody ResponseEntity<?> getTransitCertificateStates() {
        Resources<TransitCertificateStatus> resources = new Resources<TransitCertificateStatus>(
                Arrays.asList(TransitCertificateStatus.values()));
        return ResponseEntity.ok(resources);
    }

注意，这些项被转换是因为我将这些值设置为rest-messages.properties和Spring数据，rest负责转换

server.model.enums.TransitCertificateStatus.PENDING = In attesa
server.model.enums.TransitCertificateStatus.USED = Utilizzato
server.model.enums.TransitCertificateStatus.CANCELED = Annullato
server.model.enums.TransitCertificateStatus.ARCHIVED = Archiviato

到目前为止，一切都如预期的那样。 现在，我需要获得一个按bean

TransitCertificate

筛选的存储库列表，并将存储库作为REST资源直接公开：

@RepositoryRestResource
@Transactional
@PreAuthorize("isAuthenticated()")
public interface TransitCertificateRepository extends PagingAndSortingRepository<TransitCertificate, Long> {

 @Transactional(readOnly = true)
@Query("SELECT t FROM TransitCertificate t WHERE (:code IS NULL OR code=:code) AND (:date IS NULL OR DATE(createdDate)=DATE(:date)) AND (:text IS NULL OR text LIKE CONCAT('%',:text,'%')) AND (:from IS NULL OR t.from LIKE CONCAT('%',:from,'%')) AND (:customerName IS NULL OR customerName LIKE CONCAT('%',:customerName,'%')) AND (:states IS NULL OR status IN (:states)) ")
public Page<TransitCertificate> findAllByParameters(@Param("code") @RequestParam(value = "code", required = false) String code,
        @Param("date") @RequestParam(value = "date", required = false) Instant date,
        @Param("text") @RequestParam(value = "text", required = false) String text,
        @Param("from") @RequestParam(value = "from", required = false) String from,
        @Param("customerName") @RequestParam(value = "customerName", required = false) String customerName,
        @Param("states") @RequestParam(value = "states", required = false) List<TransitCertificateStatus> states, Pageable pageable);


@Transactional(readOnly = true)
@Query("SELECT t FROM TransitCertificate t WHERE (:#{#filter} IS NULL OR t.status=:#{#filter.status}) ")
public Page<TransitCertificate> findAllByParameters2(@RequestBody @RequestParam(value="filter") @Param("filter") TransitCertificateFilter filter,
        Pageable pageable);

所以我尝试了另一种方法

第二种方法

这次我创建了一个bean作为过滤器，它包含了查询中应该过滤的所有参数

    public class TransitCertificateFilter implements Serializable {

    private TransitCertificateStatus status;

    public TransitCertificateStatus getStatus() {
        return status;
    }

    public void setStatus(TransitCertificateStatus status) {
        this.status = status;
    }

}

在方法

findAllByParameters2

中，我使用SpEL从客户端发送的bean中获取属性

status

请求如下：

{
"status":"Annullato"
}

这是我回来的一个例外：

{
  "timestamp": "2017-10-12T15:46:20.292+0000",
  "status": 500,
  "error": "Internal Server Error",
  "exception": "org.springframework.expression.spel.SpelEvaluationException",
  "message": "EL1007E: Property or field 'status' cannot be found on null",
  "path": "/api/v1/transitCertificates/search/findAllByParameters2"
}

我搜索了一些关于这个的信息，但没有找到任何有用的。有人能让我走上正确的道路吗

{
"status":"Annullato"
}

{
  "timestamp": "2017-10-12T15:46:20.292+0000",
  "status": 500,
  "error": "Internal Server Error",
  "exception": "org.springframework.expression.spel.SpelEvaluationException",
  "message": "EL1007E: Property or field 'status' cannot be found on null",
  "path": "/api/v1/transitCertificates/search/findAllByParameters2"
}