MultipartFile with additional properties from Angular to Spring Boot

Question

I have the following spring-boot function that works and is able to read MultipartFiles that is sent from Angular front-end code.

@PostMapping(value = "/upload")
@Operation(summary = "Upload Files")
public ResponseEntity<Map<String, List<String>>> uploadFiles(@RequestParam("files") MultipartFile[] files) {

    List<String> exceptions = new ArrayList<>();
    List<String> fileNames = new ArrayList<>();
    
    for (MultipartFile file : files) {
        try {
            Path fileStorage = get(DIRECTORY, fileName).toAbsolutePath().normalize();
            copy(file.getInputStream(), fileStorage, true);
            fileNames.add(fileName);
        } catch (Exception e) {
            exceptions.add(e.getClass().getName() + ": " + e.getMessage());
        }
    }

    Map<String, List<String>> map = new HashMap<>();
    map.put("data", fileNames);
    map.put("errors", exceptions);
    return ResponseEntity.ok().body(map);

}

My problem is, I have a couple of properties (checksum and author) that I need to get on each file. This is the sample of the file object that gets added as FormData.

How will I be able to get them in my backend code?

Here's the Request Payload

Here's the Request Header coming from Angular

Can you show how does HTTP request look like? If it's in a request, it could be read somehow. Otherwise it's not possible. — Stefan Golubović, Nov 15 '22 at 12:35
@StefanGolubović I added a screenshot of the Payload and the Header. Is that what you're asking for? — ericute, Nov 15 '22 at 12:59
I don't see any information about hash and author in the screenshots you posted. You could try debugging your Spring method and check whether `MultipartFile` contains information you seek. Alternatively, you could try getting `MultipartHttpServletRequest` in your method and check if the request contains the information about hash and author. — Stefan Golubović, Nov 15 '22 at 14:31

score 0 · Accepted Answer · answered Nov 17 '22 at 05:41

I found this article that helped me fix my problem: https://blogs.perficient.com/2020/07/27/requestbody-and-multipart-on-spring-boot/

@PostMapping(value = "/upload", consumes = { MediaType.APPLICATION_JSON, MediaType.MULTIPART_FORM_DATA })
@Operation(summary = "Upload Files")
public ResponseEntity<Map<String, List<String>>> uploadFiles(@RequestPart("files") MultipartFile[] files,
        @RequestPart("fileUploadMetadataList") String inputFileUploadMetadataList) {

    ObjectMapper mapper = new ObjectMapper();
    CollectionType listType = mapper.getTypeFactory().constructCollectionType(ArrayList.class,
            FileUploadMetadataEntity.class);
    try {
        List<FileUploadMetadata> fileUploadMetadataList = mapper.readValue(inputFileUploadMetadataList, listType);
        /*** fileUploadMetadataList => CONTAINS EXACTLY WHAT I NEEDED ***/
    
    } catch (JsonMappingException jsonMappingError) {
        jsonMappingError.printStackTrace();
    } catch (JsonProcessingException jsonProcessingError) {
        jsonProcessingError.printStackTrace();
    }

    // ... some other statements

}

And in Angular, this is what I needed to do:

// ... some other statements

const formData = new FormData();
const fileUploadMetaDataList: FileUploadMetadata[] = [];

for (const file of this.files) {
  const fileUploadMetadata: FileUploadMetadata = {
    fileName: file.name,
    checksum: file.checksum,
    author: file.author,
    fileSize: file.size,
    lastModifiedDate: file.lastModifiedDate,
    uploadDate: new Date(),
  };
  formData.append('files', file);
  fileUploadMetaDataList.push(fileUploadMetadata);
}

formData.append(
  'fileUploadMetadataList',
  JSON.stringify(fileUploadMetaDataList)
);

// ... some other statements

MultipartFile with additional properties from Angular to Spring Boot

1 Answers1