REST API Query with a parameter

Question

I am trying to query a server that looks like this:

Server Code

@RequestMapping(value = "/query_user", method = RequestMethod.GET)
public String queryUser(@RequestParam(value="userId", defaultValue="-1") String userId)
{
    int id = Integer.parseInt(userId);
    User user = this.service.getUser(id);
    ...
    return userJson;
}

This method works when I test with PostMan

Client Code

private synchronized void callServer(int id)
{
     final String URI = "http://localhost:8081/query_user";
     RestTemplate restTemplate = new RestTemplate();
     MultiValueMap<String, Object> map = new LinkedMultiValueMap();
     map.add("userId", id);

     restTemplate.getMessageConverters()
            .add(new MappingJackson2HttpMessageConverter());

     // Modified to use getForEntity but still this is not working.
     ResponseEntity<String> response 
          = restTemplate.getForEntity(URI, String.class, map); 
}

How can I fix this? It is important that I receive the userJson from the Server side.

---

EDIT

After changing to getForEntity() method I keep getting the defaultValue of -1 on the server side. There must be something else wrong with my code. I am definitly sending a userId that is NOT -1.

Answer 1

I was able to solve it by using a UriComponentsBuilder.

UriComponentsBuilder builder = UriComponentsBuilder.fromUriString(URI)
        .queryParam("userId", id);

Essentially it is appending the parameter to the URI which is what I believe PostMan is doing (that is how I thought about it).

Reference: https://www.oodlestechnologies.com/blogs/Learn-To-Make-REST-calls-With-RestTemplate-In-Spring-Boot