将一个空的多部分文件从 angular 6 发送到 spring boot

Question

我想将图像文件发送到 spring 引导后端。上传图片时，post 请求工作 fine.But 如果没有上传图片文件，它会给我一个错误。

如果用户没有上传任何图片，我尝试发送 null。但是它给了我一个错误。

这是我的 onSubmit 函数

onSubmit() {
    // tslint:disable-next-line:max-line-length
    if ( this.addEntityForm.value.entityCode !== '' &&  this.addEntityForm.value.entity !== '' && this.addEntityForm.value.eDisplayName !== '') {

      const formData: FormData = new FormData();
      formData.append('name',this.addEntityForm.value.entityCode);
      formData.append('description',this.addEntityForm.value.entity);
      formData.append('displayName',this.addEntityForm.value.eDisplayName);
      if (this.selectedFile != null){
        formData.append('logo', this.selectedFile);
      }
      else {
        formData.append('logo', null);
      }
      formData.append('status','ACTIVE');

      console.log(formData);

      this.profileServise.addNewEntity(formData).subscribe( result => {

        if (result) {
          this.globalService.updateEntityTable(result);
        }
        this.openSnackbar('New Entity Created Successfully');
        this.matDialogRef.close();
      }, error => {
        this.openSnackbar('An Error in Creating a New Entity');
      });
    } else {
      this.openSnackbar('Please fill all required fileds !!!');
    }

  }

这是我用来选择图片的函数。

onFileChanged(event) {
    this.selectedFile = event.target.files[0];
  }

这是我的后端控制器方法

@ResponseStatus(HttpStatus.OK)
    @RequestMapping(value = "/addNewEntity", method = RequestMethod.POST)
    public ResponseEntity<CompanyDTO> photoUploaded(@RequestParam(value = "name", required = true) String name,
                                                    @RequestParam(value = "description", required = true) String desc,
                                                    @RequestParam(value = "displayName", required = true) String displayName,
                                                    @RequestParam(value = "logo", required = true) MultipartFile logo,
                                                    @RequestParam(value = "status", required = true) String status
    ) {

        // getting file extension
        String fileExtension = logo.getOriginalFilename().substring(logo.getOriginalFilename().lastIndexOf(".")+1);

        //convert to bytes
        byte[] image = new byte[0];

        try {
             image = logo.getBytes();
        } catch (IOException e) {
            e.printStackTrace();
        }


        Company company = new Company();
            company.setName(name);
            company.setDescription(desc);
            company.setDisplayName(displayName);
            company.setLogo(image);
            company.setStatus(status);
            this.companyService.saveCompany(company);
            log.debug("edited entity"+company.getName());


        CompanyDTO newrow = new CompanyDTO(company.getId(),company.getName(),company.getDescription(),company.getDisplayName(),company.getLogo(),company.getStatus());

        return new ResponseEntity<>( newrow,HttpStatus.OK);

    }

如果用户没有选择图片，我将发送 'null'。它给了我这个错误

org.springframework.web.bind.MissingServletRequestParameterException: Required MultipartFile parameter 'logo' is not present```

Answer 1

您将 API POST 参数标记为 required=true，如果参数是可选的并且可以包含 null 值，则需要将其标记为 required=false

@RequestMapping(value = "/addNewEntity", method = RequestMethod.POST)
    public ResponseEntity<CompanyDTO> photoUploaded(@RequestParam(value = "name", required = true) String name,
                                                    @RequestParam(value = "description", required = true) String desc,
                                                    @RequestParam(value = "displayName", required = true) String displayName,
                                                    @RequestParam(value = "logo", required = false) MultipartFile logo,
                                                    @RequestParam(value = "status", required = true) String status
    )

将一个空的多部分文件从 angular 6 发送到 spring boot

Sending an empty multipart file from angular6 to springboot

multipartform-data

spring-boot

angular6