java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast or BeanUtils.copyProperties not working

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am new to JPA and springboot unable to get the api response when am using @Query param(I try achieve the inner join)

Repositoty class:

 @Transactional(rollbackFor = Exception.class)
    @Modifying
    @Query("select A.id, A.position ,A.title,A.shortdescription,A.thumbnailimage, A.linkactions, A.last_updated_date, A.last_updated_by, B.countryName " +
            "from ContentManage as A inner join Country as B on A.countryid=B.countryId")
    List<ContentManage> fetchDataInnerJoin();

Service class:

public ContentManageListResponse queryAllActions() {
        List<ContentManage> contentManageList = contentManageRepository.fetchDataInnerJoin();
        List<ContentManageVO> contentManageVOList = new ArrayList<>();
        for (ContentManage contentManage : contentManageList) {
            ContentManageVO contentManageVO = new ContentManageVO();
            BeanUtils.copyProperties(contentManage,contentManageVO);
            contentManageVOList.add(contentManageVO);
        }
        return ContentManageListResponse.builder().contents(contentManageVOList).build();
    }

am getting the ” [Ljava.lang.Object; cannot be cast ” exception after that I have changed to as below:

service class

public ContentManageListResponse queryAllActions() {
        List<ContentManage> contentManageList = contentManageRepository.fetchDataInnerJoin();
        List<ContentManageVO> contentManageVOList = new ArrayList<>();
        for (Object contentManage : contentManageList) {
            ContentManageVO contentManageVO = new ContentManageVO();
            BeanUtils.copyProperties(contentManage,contentManageVO);
            contentManageVOList.add(contentManageVO);
        }
        return ContentManageListResponse.builder().contents(contentManageVOList).build();
    }

foreach added the Object but for the above code am getting null values BeanUtils.copyProperties is not working

please any one suggest how to fix this.

Answer

Your statement

@Query("select A.id, A.position ,A.title,A.shortdescription,A.thumbnailimage, A.linkactions, A.last_updated_date, A.last_updated_by, B.countryName " +
            "from ContentManage as A inner join Country as B on A.countryid=B.countryId")

contains parts from ContentManage and Country in select. But your result is only a List<ContentManage>

To solve this you can create a new Dto class containing all the fields from A and from B you need. This Dto class must have an all-args constructor. Then instead of

 "select A.id, A.position ,A.title,A.shortdescription,A.thumbnailimage, A.linkactions, A.last_updated_date, A.last_updated_by, B.countryName " +
            "from ContentManage as A inner join Country as B on A.countryid=B.countryId"

you can write:

"select new com.you.package.YourDtoClass (A.id, A.position ,A.title,A.shortdescription,A.thumbnailimage, A.linkactions, A.last_updated_date, A.last_updated_by, B.countryName) " +
            "from ContentManage as A inner join Country as B on A.countryid=B.countryId"


Source: stackoverflow