File upload spring cloud feign client

After few days searching a solution I found this. You should start to add feign form for spring dependency :

<dependency>
   <groupId>io.github.openfeign.form</groupId>
   <artifactId>feign-form-spring</artifactId>
   <version>3.3.0</version>
</dependency

Then your feign client need this spring form encoder :

@FeignClient(
    name="attachment-service",  
    configuration = {AttachmentFeignClient.MultipartSupportConfig.class}
    fallback=AttachmentHystrixFallback.class)
public interface AttachmentFeignClient {

@RequestMapping(value= {"upload"}, consumes = {"multipart/form-data"})
void upload(
    @RequestPart(name="file") MultipartFile file, 
    @RequestParam(name="attachableId") Long attachableId, 
    @RequestParam(name="className") String className,
    @RequestParam(name="appName") String appName);

 public class MultipartSupportConfig {
    @Bean
    @Primary
    @Scope("prototype")
    public Encoder feignFormEncoder() {
        return new SpringFormEncoder();
    }
  }
}

I hope it will help someone.

Update 13/01/2020
Configure FeignClient to handle MultiPartFile with @RequestPart
Note that this approach is suitable only if you have one RequestPart that represents the whole body. Having multiple RequestPart is another problem with FeignClient.

The configuration of the feignclient is similar to what @marting-choraine did, but by adding the extra Encoder Configuration in the FeignConfigurationClass.

So with the same example that I provide below, instead of implementing a custom mapper, you will need to do something like this

@Configuration
@EnableFeignClients(basePackages = "YourPackage")
public class FeignConfiguration {

  @Bean
  public Encoder feignFormEncoder(ObjectFactory<HttpMessageConverters> messageConverters) {
      return new SpringFormEncoder(new SpringEncoder(messageConverters));
  }
}

TL;DR
Transform your MultiPartFile to MultiValueMap. See example below

The answer mentioned by @martin-choraine is the proper and the best answer to have your FeignClient method signature, the same as the actual endpoint signature that you are trying to call. However, there is a way around that does not require you to define a FormEncoder or add any extra dependency because in some applications you are not allowed to do that (enterprise shit); all what you need is to transform your MultipartFile to a MultiValueMap and it will perfectly work as the standard encoder will be able to serialize it.

Actual EndPoint to be called

@PostMapping(path = "/add", consumes = MULTIPART_FORM_DATA_VALUE, produces = APPLICATION_JSON_VALUE)
 public MyResponseObject add(@RequestParam(name = "username") String username,
                             @RequestPart(name = "filetoupload") MultipartFile file) {
              Do something
}

The POST method in your FeignClient should look like this

@PostMapping(path = "/myApi/add", consumes = MULTIPART_FORM_DATA_VALUE, 
              produces = APPLICATION_JSON_VALUE)
 public MyResponseObject addFile(@RequestParam(name = "username") String username,
                           @RequestPart(name = "filetoupload") MultiValueMap<String, Object> file);

Then when you call the addFile you should provide MultiValueMap like this

public MyResponseObject addFileInAnotherEndPoint(String username, MultipartFile file) throws IOException {

    MultiValueMap<String, Object> multiValueMap = new LinkedMultiValueMap<>();
    ByteArrayResource contentsAsResource = new ByteArrayResource(file.getBytes()) {
        @Override
        public String getFilename() {
            return file.getOriginalFilename();
        }
    };
    multiValueMap.add("filetoupload", contentsAsResource);
    multiValueMap.add("fileType", file.getContentType());
    return this.myFeignClient.addFile(username, multiValueMap);
}

i have added consumes = MediaType.MULTIPART_FORM_DATA_VALUE in the post and it works for me. this is my feign client method and in the front i worked with formdata

@PostMapping(path=Urls.UPLOAD_FILE_IN_LIBELLE, consumes = MediaType.MULTIPART_FORM_DATA_VALUE )
    public void uploadFileInLibelle(
            @RequestParam String processus,
            @RequestParam String level0Name,
            @RequestParam String nomFichier,
            @RequestParam String nomLibelle,
            @RequestParam String anneeFolderName,
            @RequestParam String semaineFolderName,
            @RequestPart   MultipartFile fichier);

this is my angular frontent

public uploadFiles(
        nomFichier: string,
        nomLibelle: string,
        processus: string,
        level0Name: string,
        semaineFolderName: string,
        anneeFolderName: string,
        byte: File
    ): Observable<any> {
        const formData = new FormData();
        formData.set('processus', processus);
        formData.set('level0Name', level0Name);
        formData.set('nomLibelle', nomLibelle);
        formData.set('anneeFolderName', anneeFolderName);
        formData.set('semaineFolderName', semaineFolderName);
        formData.set('nomFichier', nomFichier);
        formData.set('fichier', byte);

        return this.httpClient.post(this.urlUploadFile, formData);
    }