java发送文件和json Spring引导和角度

Question

我想将一个表单数据对象从角度“front”发送到spring boot“back” 我犯了以下错误

Bad Request: Failed to convert value of type 'java.lang.String' to required type 'java.lang.Long'; nested exception is java.lang.NumberFormatException: For input string: "null"

create(document: IDocument, fichier: File | undefined): Observable<EntityResponseType> {
    const formData: FormData = new FormData();

    const documentDTO = new Blob([JSON.stringify({document})], {type: 
    formData.append('documentDTO', documentDTO);
    if (fichier !== undefined) {
      formData.append('fichier', fichier);
    }
    return this.http.post(this.resourceUrl, formData, { observe: 'response' });
  }
  
  
  
  
   @PostMapping(value = "/documents",
        produces = MediaType.APPLICATION_JSON_VALUE,
        consumes = {MediaType.APPLICATION_JSON_VALUE, MediaType.MULTIPART_FORM_DATA_VALUE})
    public ResponseEntity<DocumentDTO> createDocument(@RequestPart("documentDTO") DocumentDTO documentDTO,
                                                      @RequestPart("fichier") MultipartFile fichier) throws URISyntaxException, SQLException {
        log.debug("=========================", documentDTO.toString());
        log.debug("+++++++++++++++++++++++++++++++++", fichier.getName());
        this.documentService.init();
        try {
            Files.copy(fichier.getInputStream(), this.root.resolve(fichier.getOriginalFilename()));
        } catch (Exception e) {
            throw new RuntimeException("Could not store the file. Error: " + e.getMessage());
        }
        if (documentDTO.getId() != null) {
            throw new BadRequestAlertException("A new document cannot already have an ID", ENTITY_NAME, "idexists");
        }
        DocumentDTO result = documentService.save(documentDTO);
        return ResponseEntity
            .created(new URI("/api/documents/" + result.getId()))
            .headers(HeaderUtil.createEntityCreationAlert(applicationName, true, ENTITY_NAME, result.getId().toString()))
            .body(result);
    }