如果为 null，Java Spring 不会返回 DTO 对象？

Question

我有一个 Java 实现 Override 方法，它根据输入的参数从 2 个微服务返回 DTO 对象结果。

我能够获得过滤的搜索结果，但是在不满足第二个服务条件的情况下我收到“空”我希望获得不返回空对象的结果。我如何能够返回满足所有条件的结果指定参数？

下面我提供了我使用“Swagger”收到的响应的屏幕截图以及执行所有魔力的代码片段。

我是否需要使用 ObjectMapper 或类似 @JsonInclude(Include.NON_NULL) 的东西，但是我可以在服务植入中和 DTO 对象中使用它吗？

任何进一步的建议或想法弹跳将不胜感激。

我在之前的问题 Java pass variable into mapped DTO method? 的基础上进一步发展

招摇回应:

代码片段:

    @Override
public Page<ProfileCreditDTO> findProfileBySelectedParameters(String username, Integer gender, Integer profileType, Integer orientation, Boolean online, Double profileCredit, Integer creditMode, Double creditTotal, Pageable pageable) {
    Page<Profile> searchData= profileRepository.findByAllParameters(username, gender, profileType, orientation, online, pageable);
    Page<ProfileCreditDTO> searchProfileData=null;
    if(searchData != null)
        searchProfileData = searchData.map(x -> this.convertProfileToProfileCreditDTO(x, profileCredit, creditMode, creditTotal));
    return searchProfileData;
}


public ProfileCreditDTO convertProfileToProfileCreditDTO(final Profile theProfile, Double profileCredit, Integer creditMode, Double creditTotal)  {
    if(theProfile == null)
        return null;
    ProfileCreditDTO theDTO= new ProfileCreditDTO();
    theDTO.setProfile(theProfile);
    CreditDTO theCreditDto = profileCreditClient.findClientByProfileId(theProfile.getId(), profileCredit, creditMode, creditTotal);
    log.error(String.valueOf(theCreditDto));
    if (theCreditDto != null)
        theDTO.setCredit(theCreditDto);
    else {
        return null;
    }

    return theDTO;
}

已更新

我尝试将 @JsonInclude(Ininclude.NON_NULL) 添加到 ProfileCredit DTO 中，但仍然没有任何结果，也在 CreditDTO 中添加了相同的内容。

ProfileCredit DTO:

 @Data
@AllArgsConstructor
@NoArgsConstructor
@ToString
@JsonInclude(JsonInclude.Include.NON_NULL)
public class ProfileCreditDTO {
    // profile fields
    private Long profileId;
    @Size(min = 2, max = 50)
    private String username;
    private Integer gender;
    private Integer profileType;
    private Integer orientation;
    private boolean online;


    // Credit fields
    private Long creditId;
    @Column(unique = true)
    private Double profileCredit;  //X
    private Integer creditMode;
    private Integer creditCheck;
private Double creditTotal;

/**
 * set the profile derived data
 * @param profile
 */
public void setProfile(final Profile profile){
    this.setProfileId(profile.getId());
    this.setUsername(profile.getUsername());
    this.setGender(profile.getGender());
    this.setProfileType(profile.getProfileType());
    this.setOrientation(profile.getOrientation());
    this.setOnline(profile.isOnline());
}

/**
 * Set the credit aspect
 * @param credit
 */
public void setCredit(final CreditDTO credit){
    this.setCreditId(credit.getId());
    this.setProfileId(credit.getProfileId());
    this.setProfileCredit(credit.getProfileCredit());
    this.setCreditMode(credit.getCreditMode());
    this.setCreditTotal(credit.getCreditTotal());

}

当我在实现中未指定 return null; 时，响应如下所示。正如您所看到的，所有满足条件 1 但不满足条件 2 的对象都会返回空对象字段。

Answer 1

作为元素的“对象”不能直接从页面中删除。您可以做的是，从页面中获取内容，该内容将是一个列表，然后根据您的条件从列表中删除元素，然后使用页面所需的数据字段创建一个新页面。

而不是

    @Override
public Page<ProfileCreditDTO> findProfileBySelectedParameters(String username, Integer gender, Integer profileType, Integer orientation, Boolean online, Double profileCredit, Integer creditMode, Double creditTotal, Pageable pageable) {
    Page<Profile> searchData= profileRepository.findByAllParameters(username, gender, profileType, orientation, online, pageable);
    Page<ProfileCreditDTO> searchProfileData=null;
    if(searchData != null)
        searchProfileData = searchData.map(x -> this.convertProfileToProfileCreditDTO(x, profileCredit, creditMode, creditTotal));
    return searchProfileData;
}

尝试

   @Override
public Page<ProfileCreditDTO> findProfileBySelectedParameters(String username, Integer gender, Integer profileType, Integer orientation, Boolean online, Double profileCredit, Integer creditMode, Double creditTotal, Pageable pageable) {
    Page<Profile> searchData= profileRepository.findByAllParameters(username, gender, profileType, orientation, online, pageable);
    Page<ProfileCreditDTO> searchProfileData=null;
    if(searchData != null)
        searchProfileData = searchData.map(x -> this.convertProfileToProfileCreditDTO(x, profileCredit, creditMode, creditTotal));

    List modifiedAppList = searchProfileData.getContent().stream().filter(v -> v !=null).collect(Collectors.toList()); //Will filter your search result and put it into a list

    Page<ProfileCreditDTO> filteredList = new PageImpl<>(modifiedAppList, new PageRequest(0, searchProfileData.getSize()), searchProfileData.getTotalElements()); //Will put your filtered list back into page

    return  filteredList; //Returns filtered result

}

从 Spring Data Rest - How to remove an element from a Page? 得到了这个问题的答案仅修改了代码和措辞的位，因为答案已经正确了;)