I'm trying to store images in MySQL using Spring boot, I have a user entity and I want to create a Many To One relationship between my FileUpload entity.

I'm using react on the front end and the purpose of this upload service is to have profile pictures that a user can set themselves but I'd first like to get the relationship between the User and FileUpload entities correct.

The issue I have is that the joinColumn in the FileUpload table does not save the User Entities id when a user uploads an image. It just returns a null value in the foreign key field.

FileUpload.java

@Entity
@Table(name="file_upload")
public class FileUpload {

    @Id
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @GeneratedValue(generator = "uuid")
    private String id;

    private String name;

    private String type;

    @Lob
    private byte[] data;

    @ManyToOne
    @JoinColumn( name="user_id")
    private User user;

    public FileUpload() {

    }

    public FileUpload(String name, String type, byte[] data) {
        this.name = name;
        this.type = type;
        this.data = data;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public byte[] getData() {
        return data;
    }

    public void setData(byte[] data) {
        this.data = data;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }
}

FileUploadService.java

• I also have a repository for this, with no custom methods inside.

@Service
public class FileUploadService {
    @Autowired
    private FileUploadRepository fileUploadRepository;

    public FileUpload store(MultipartFile file) throws IOException {
        String fileName = StringUtils.cleanPath(file.getOriginalFilename());
        FileUpload fileDB = new FileUpload(fileName, file.getContentType(), file.getBytes());

        return fileUploadRepository.save(fileDB);
    }

    public FileUpload getFile(String id) {
        return fileUploadRepository.findById(id).get();
    }

    public Stream<FileUpload> getAllFiles() {
        return fileUploadRepository.findAll().stream();
    }
}

FileUploadController.java

@Controller
@CrossOrigin()
public class FileUploadController {

    @Autowired
    private FileUploadService fileUploadService;

    @PostMapping("/upload")
    public ResponseEntity<?> uploadFile(@RequestParam("file")MultipartFile file) {
        String message = "";
        try {
            fileUploadService.store(file);

            message = "Uploaded the file successfully: "   file.getOriginalFilename();
            return ResponseEntity.status(HttpStatus.OK).body(new ApiResponse(true, message));
        } catch (Exception e) {
            message = "Could not upload the file: "   file.getOriginalFilename()   "!";
            return ResponseEntity.status(HttpStatus.EXPECTATION_FAILED).body(new ApiResponse(true, message));
        }
    }


    @GetMapping("/files")
    public ResponseEntity<List<?>> getListFiles() {
        List<FileUploadResponse> files = fileUploadService.getAllFiles().map(dbFile -> {
            String fileDownloadUri = ServletUriComponentsBuilder
                    .fromCurrentContextPath()
                    .path("/files/")
                    .path(dbFile.getId())
                    .toUriString();

            return new FileUploadResponse(
                    dbFile.getName(),
                    fileDownloadUri,
                    dbFile.getType(),
                    dbFile.getData().length);
        }).collect(Collectors.toList());

        return ResponseEntity.status(HttpStatus.OK).body(files);
    }

    @GetMapping("/files/{id}")
    public ResponseEntity<byte[]> getFile(@PathVariable String id) {
        FileUpload fileUpload = fileUploadService.getFile(id);

        return ResponseEntity.ok()
                .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\""   fileUpload.getName()   "\"")
                .body(fileUpload.getData());
    }

}

Postman POST request

MySQL Tables User

FileUpload

I have the same relationship with a confirmation token entity i have to confirm a users email which does work properly with the ManyToOne relationship but this doesn't. I am using the same relationship mapping but it gives me null values as seen above.

   @ManyToOne
    @JoinColumn( name="user_id")
    private User user;

I can upload the file fine but I want to be able to keep track of a user and their files.

CodePudding user response：

You need to assign a user to this entity:

        FileUpload fileDB = new FileUpload(fileName, file.getContentType(), file.getBytes());
        fileDB.setUser(userThatSentImage); // you need to set user
        return fileUploadRepository.save(fileDB);

How do you authenticate users? If you are using spring security, here you can find how to retrieve user from session: https://www.baeldung.com/get-user-in-spring-security