[FIXED] Passing HttpServletRequest to another API controller

Issue

I have a controller that receives HttpServletRequest with body form-data with some key-value

I want to pass this HttpServletRequest to another API. That another API controller receives HttpServletRequest

So far, I've tried this in my service class.

public void saveApi(HttpServletRequest request) throws Exception {
    System.out.println(request.getCode());
    RestTemplate restTemplate = new RestTemplate();         
    HttpServletRequest result = restTemplate.postForObject( "http:localhost:8080/save", request, HttpServletRequest .class);
}

The result is the other API java.lang.NullPointerException: null, other API didn't receive my post.

How to do that? Is it possible?

Another service, for example: GET method, I use the RestTemplate to call to another API with some parameter, it succeeds.

UPDATE

the answer is:

HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.setContentType(MediaType.MULTIPART_FORM_DATA);

MultiValueMap<String, Object> form = new LinkedMultiValueMap<>();
form.add("name", request.getParameter("name"));
form.add("blabla", request.getParameter("blabla"));
form.add("blabla", request.getParameter("blabla"));

HttpEntity<MultiValueMap<String, Object>> requestEntity = new HttpEntity<>(form, httpHeaders);
restTemplate.postForEntity("http:localhost:8080/save", requestEntity, String.class);

Solution

Using RestTemplate::postForObject and this class in general you have to pass the correct request object:

The request parameter can be a HttpEntity in order to add additional HTTP headers to the request, that is HttpEntity with body and headers.

Note the HttpServletRequest extends ServletRequest.

1. Extract body using either ServletRequest::getInputStream or ServletRequest::getReader. In case of multipart/form-data use HttpServletRequest::getParts
2. Serialize the bytes of body to an object that is required for POST http:localhost:8080/save.
3. Use the object and create new HttpEntity(T body).
4. Pass it as request inside the RestTemplate::postForObject method.

The exact steps might differ regarding what data you need, the point is you cannot pass HttpServletRequest directly but use an instance of HttpEntity.

Answered By - Nikolas Charalambidis
Answer Checked By - Senaida (JavaFixing Volunteer)