OpenApi send MultipartFile request with JSON get 'application / octet-stream' error not supported

Question

I'm using Spring Boot and I want to send MultipartFile with json using Swagger UI but I receive the error 'application/octet-stream' error not supported,if I use Postman work very well.

@ResponseBody
@RequestMapping(value = "/upload", method = RequestMethod.POST,
produces = { "application/json" },
consumes = { "multipart/form-data" })
public String hello(
   @RequestPart(value = "file") MultipartFile file,
   @RequestPart("grupo") Grupo grupo) {
      if (file != null) {
        logger.info("File name:  " + file.getOriginalFilename());
      }
      logger.info(grupo.toString());
   return grupo.toString();
 }

How do I solve this?

• springdoc-openapi-ui 1.4.4
• Spring Boot 2.3.2.RELEASE
• spring-boot-starter-web
• Maven
• spring-boot-starter-data-jpa

Caprine

Answer 1

To send a json with multipartFile, use the annotation @Parameter with type "string" and format "binary", so that you can send a file with format json.

@Parameter(schema =@Schema(type = "string", format = "binary"))

And then it will be like this.

@PostMapping(value = "/test", consumes = MediaType.MULTIPART_FORM_DATA_VALUE )
public ResponseEntity<Void> saveDocu2ment(
        @RequestPart(value = "personDTO") @Parameter(schema =@Schema(type = "string", format = "binary")) final PersonDTO personDTO,
        @RequestPart(value = "file")  final MultipartFile file) {
    return null;
}

Reference - Multipart Request with JSON - GitHub Springdoc openApi

Caprine

How can this be an accepted answer, why would i send a json as a file !! – Torn

@Torn No, JSON you send your data who is "personDTO"* like: name, age, email, etc, and the "file" you send your file, so this is mixed json with file sharing on an endpoint – Caprine

it's not an actual answer but maybe workaround, it's accepting json as well as a binary file: check this prnt.sc/X90pOyBMBaJ9 – Maypole

This is right solution actually, github.com/swagger-api/swagger-ui/issues/… – Maypole

Answer 2

Following the link provided by @Vishal Zanzrukia

I added this configuration:

import java.util.ArrayList;

import org.springframework.boot.info.BuildProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.http.MediaType;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;



@Configuration
public class OpenApiConfig {

    /**
     * 
     * This method is needed to allow sending multipart requests. For example, when an item is 
     * created together with an image. If this is not set the request will return an exception with:
     * 
     * Resolved [org.springframework.web.HttpMediaTypeNotSupportedException: Content-Type 
     * 'application/octet-stream' is not supported]
     * 
     * @param converter
     */
    public OpenApiConfig(MappingJackson2HttpMessageConverter converter) {
        var supportedMediaTypes = new ArrayList<>(converter.getSupportedMediaTypes());
        supportedMediaTypes.add(new MediaType("application", "octet-stream"));
        converter.setSupportedMediaTypes(supportedMediaTypes);
    }
...

And now it seems to be working as expected with a code like this: Controller.java

    @PostMapping(path = "/", consumes = MediaType.APPLICATION_JSON_VALUE)
    public ResponseEntity<Item> createItemWithoutImage(@Valid @RequestBody Item item) {
        Item createdItem = itemService.createItem(item);
        return ResponseEntity.status(HttpStatus.CREATED).body(createdItem);
    }

    @PostMapping(path = "/", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public ResponseEntity<Item> createItem(@Valid @RequestPart Item item,
            @RequestPart(name = "image", required = false) MultipartFile imageFile) {

        // DO Something with the image

        Item createdItem = itemService.createItem(item);
        return ResponseEntity.status(HttpStatus.CREATED).body(createdItem);
    }

This is how it looks in swagger:

Ashwell