MultipartFile + String as Request Param using RestTemplate in Spring

Question

In my spring boot Application, I need to pass String value along with MultipartFile as Requestparam. Controller is below where I'm converting MultipartFile to java.io.File and then passing it to DAO controller with help of restTemplate.

Request from Angular will hit Upload Controller first then UploadController is client(Java) and it will be calling server svs-ba-dao Controller with Base URL. csvUpload contains base URL: http://localhost:8082/svs-ba-dao/csvUpload?parentPkId=&file=multipartFile

@CrossOrigin
@RestController
public class UploadController {

    private static final Logger log = LogManager.getLogger(UploadController.class);

    @Value("${salama.dao.csvUpload.rest.url}")
    private String csvUpload;
    
    @Autowired
    UploadHelperService uploadHelperService;
    
    @PostMapping(value = "/csvUpload")
    public String csvUpload(@QueryParam("parentPkId") String parentPkId, @RequestParam("file") MultipartFile file ) throws IllegalStateException, IOException{
        
        log.info("Calling csvUpload :" + csvUpload);
        final HttpHeaders requestHeaders = new HttpHeaders();
        requestHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);

        File cnvFile = uploadHelperService.multipartToFile(file,file.getOriginalFilename());
        System.out.println("Converted File Name is -->"+cnvFile.getName());
        final MultiValueMap<String, Object> data = new LinkedMultiValueMap<>();
        
        data.add("parentPkId", parentPkId);
        data.add("file", new FileSystemResource(cnvFile));
        
    HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<MultiValueMap<String, Object>>(data, requestHeaders);
    
        RestTemplate restTemplate = new RestTemplate();
        
        ResponseEntity<String> obj =restTemplate.exchange(csvUpload, HttpMethod.POST,
            requestEntity, String.class);
        
        return obj.getBody();
}
    
    
}

In svs-ba-dao Controller catching it as below

@RequestMapping(value="/csvUpload", method=RequestMethod.POST)
    public String csvUpload(@RequestParam String parentPkId, @RequestParam MultipartFile file) throws IOException {
        log.info("Entered method csvUpload() of svs-ba-dao.class");
        return uploadService.csvUpload(parentPkId,file);
    }

I have included these properties into the application.properties file of my application: spring.servlet.multipart.maxFileSize=1MB spring.servlet.multipart.maxRequestSize=1MB

So I start my application and call the /csvUpload that generate the POST request. i'm getting below error.

Converted File Name is -->testInput_TxnMpMotSlv.csv
2019-01-24T15:12:41,217 ERROR [[localhost].[/svs-ba-dao].[dispatcherServlet]] [http-nio-8085-exec-2] Servlet.service() for servlet [dispatcherServlet] in context with path [/svs-ba-dao] threw exception [Request processing failed; nested exception is org.springframework.web.client.HttpServerErrorException: 500 null] with root cause
org.springframework.web.client.HttpServerErrorException: 500 null
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:97) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:79) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:766) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:724) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:680) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:600) ~[spring-web-5.0.6.RELEASE.jar:5.0.6.RELEASE]
    at com.svs-ba-dao.controller.UploadController.csvUpload(UploadController.java:59) ~[classes/:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_192]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_192]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_192]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_192]

Error is in resttemplate as it is taking null, but syntactically way of calling RestTemplate is correct as i'm not getting any error. am I calling Base URLproperly?by passing requestparam values. i.e parentPkId=?&file=multipartFile

http://localhost:8082/svs-ba-dao/csvUpload?parentPkId=&file=multipartFile
honestly i haven't worked on this before. Where i'm doing wrong, any leads or corrections welcomed. Thanks in advance

Answer 1

Here I found where I was wrong

csvUpload will hold the URL which should be passed in rest template

 @Value("${salama.dao.csvUpload.rest.url}")
        private String csvUpload;

I found that base URL: i.e csvUpload http://localhost:8082/svs-ba-dao/csvUpload?parentPkId=&file=multipartFile sending from UploadController was wrong.

No need to specify anything like multipartFile for mediaType in URL. it will automatically pick up. but for some of the URL's need to specify ?mediaType=json if sending JSON object.

Here is my updated base URL :http://localhost:8082/svs-ba-dao/csvUpload?parentPkId=&file=

Answer 2

There is no problem in calling. Look at your stack trace error carefully. In csvUpload method you print this:

System.out.println("Converted File Name is -->"+cnvFile.getName());

this line printed in log:

Converted File Name is -->testInput_TxnMpMotSlv.csv

So calling was ok. problem in here:

at com.svs-ba-dao.controller.UploadController.csvUpload(UploadController.java:59)

Just check at line number 59 in csvUpload method of UploadController. you will find your error.

Look at this. how to call multipart using rest template.

Answer 3

You can do a few things to understand what is actually happening:

1. Try calling your endpoint for csvUpload in svs-ba-dao Controller from postman to see if it is working independently. Also, update your csvUpload method to

   @RequestMapping(value="/csvUpload", method=RequestMethod.POST) public String csvUpload(@RequestParam("parentPkId") String parentPkId, @RequestParam("file") MultipartFile file) throws IOException { log.info("Entered method csvUpload() of svs-ba-dao.class"); return uploadService.csvUpload(parentPkId,file); }

2. Surround your RestTemplate call to try-catch

   ResponseEntity<String> obj =restTemplate.exchange(csvUpload, HttpMethod.POST, requestEntity, String.class);

in order to see an exception which is coming from svs-ba-dao Controller.