RestTemplate.exchange doesn't work properly. Missing params thrown

Question

I've got 2 aplication one calling another. In the first one I have

RestTemplate restTemplate = new RestTemplate();
                HttpHeaders headers = new HttpHeaders();
                MultiValueMap<String, Object> parameters = new LinkedMultiValueMap<>();
                parameters.add("stationFrom", stationfrom);
                parameters.add("stationTo", stationto);
                parameters.add("operator", 5);
                parameters.add("dateTimeFrom", sdfnative.format(sdfeskm.parse(departuredate)));
                parameters.add("dateTimeTo", sdfnative.format(sdfeskm.parse(departuredate).getTime() + 60*60*1000));
                HttpEntity<MultiValueMap<String, Object>> request = new HttpEntity<>(parameters, headers);
                jsonTrain = restTemplate.exchange(url, HttpMethod.GET, request, String.class).toString();

the url is defined as global http://ip:8090/connection/search When I'm looking at the request I can see that every parameter has it's proper value, but in the restTemplate.exchange line I got error "Parameter stationFrom is missing"

My endpoint on provided IP looks like :

@GetMapping(value = "/connection/search")
public ResponseEntity<String> getConnection(@RequestParam(value = "stationFrom") int stationFrom,
                                @RequestParam(value = "stationTo") int stationTo,
                                @RequestParam(value = "operator") int operator,
                                @RequestParam(value = "dateTimeFrom") String dateTimeFrom,
                                @RequestParam(value = "dateTimeTo") String dateTimeTo) throws JSONException

I don't know why it throws me this error if stationFrom has for example value 40 and I can see it in debug/logs

Of course calling provided endpoint from postman, with the same data gives me expected result :)

Answer 1

You are passing the query parameters (RequestParams) as headers.

Check the following example how to pass RequestParams:

public void findUserById() 
{
        String username = "chathuranga";
        String password = "123";
        Integer userId = 1;

        String url = "http://localhost:" + port + "/users/" + userId;

        //setting up the HTTP Basic Authentication header value
        String authorizationHeader = "Basic " + DatatypeConverter.printBase64Binary((username + ":" + password).getBytes());

        HttpHeaders requestHeaders = new HttpHeaders();
        //set up HTTP Basic Authentication Header
        requestHeaders.add("Authorization", authorizationHeader);
        requestHeaders.add("Accept", MediaType.APPLICATION_JSON_VALUE);

        //request entity is created with request headers
        HttpEntity<AddUserRequest> requestEntity = new HttpEntity<>(requestHeaders);

        //adding the query params to the URL
        UriComponentsBuilder uriBuilder = UriComponentsBuilder.fromHttpUrl(url)
                .queryParam("name", "chathuranga")
                .queryParam("email", "chathuranga.t@gmail.com");

        ResponseEntity<FindUserResponse> responseEntity = restTemplate.exchange(
                uriBuilder.toUriString(),
                HttpMethod.GET,
                requestEntity,
                FindUserResponse.class
        );

        if (responseEntity.getStatusCode() == HttpStatus.OK) {
            System.out.println("response received");
            System.out.println(responseEntity.getBody());
        } else {
            System.out.println("error occurred");
            System.out.println(responseEntity.getStatusCode());
        }
}