How can I modify the object of a post call in filter. Spring boot

Question

I have a filter in my application

@Component
@Order(2)
public class RequestResponseLoggingFilter implements Filter {

    @Override
    public void doFilter(
      ServletRequest request, 
      ServletResponse response, 
      FilterChain chain) throws IOException, ServletException {

        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        // SET VALUE OF OBJECT
    }

    // other methods
}

I have a Restcall which uses a class.

@RequestMapping
Class Test{
  @PostMapping("/test")
  public void postEntry(@Valid @RequestBody Testing testing){
  }
}

Class Testing{
@NotNull(message="ERROR")  
String id;

....
}

I get the id in my filter and I would like to set the id of Testing class in my Filter. Is this possible?

score 4 · Accepted Answer · answered Jul 27 '18 at 04:59

You can use MockHttpServletRequest something like this

@Test
public void testAddEventWithWebAuthenticationDetails() {
    HttpSession session = new MockHttpSession(null, "test-session-id");
    MockHttpServletRequest request = new MockHttpServletRequest();
    request.setSession(session);
    request.setRemoteAddr("1.2.3.4");
    WebAuthenticationDetails details = new WebAuthenticationDetails(request);
    Map<String, Object> data = new HashMap<>();
    data.put("test-key", details);
    AuditEvent event = new AuditEvent("test-user", "test-type", data);
    customAuditEventRepository.add(event);
    List<PersistentAuditEvent> persistentAuditEvents = persistenceAuditEventRepository.findAll();
    assertThat(persistentAuditEvents).hasSize(1);
    PersistentAuditEvent persistentAuditEvent = persistentAuditEvents.get(0);
    assertThat(persistentAuditEvent.getData().get("remoteAddress")).isEqualTo("1.2.3.4");
    assertThat(persistentAuditEvent.getData().get("sessionId")).isEqualTo("test-session-id");
}

More examples here

or

if you want to do it filter way

few Points Before that

Request body can be read only once.
If you read the body in a filter, the target servlet will not be able to re-read it and this will also cause IllegalStateException.
You will need ServletRequestWrapper or its child: HttpServletRequestWrapper so that you can read HTTP request body and then the servlet can still read it later.

Workflow will be

The only way would be for you to consume the entire input stream yourself in the filter.
Take what you want from it, and then create a new InputStream for the content you read.

Put that InputStream in to a ServletRequestWrapper (or HttpServletRequestWrapper).

// Sample Wrapper class where you can read body and modify body content

 public class SampleHttpServletRequest 

        extends HttpServletRequestWrapper {

  private ByteArrayOutputStream cachedBytes;

  public SampleHttpServletRequest(HttpServletRequest request) {
    super(request);
  }

  @Override
  public ServletInputStream getInputStream() throws IOException {
    if (cachedBytes == null)
      cacheInputStream();

      return new CachedServletInputStream();
  }

  @Override
  public BufferedReader getReader() throws IOException{
    return new BufferedReader(new InputStreamReader(getInputStream()));
  }

  private void cacheInputStream() throws IOException {
    cachedBytes = new ByteArrayOutputStream();
    IOUtils.copy(super.getInputStream(), cachedBytes);
  }

  public class CachedServletInputStream extends ServletInputStream {
    private ByteArrayInputStream input;

    public CachedServletInputStream() {
      input = new ByteArrayInputStream(cachedBytes.toByteArray());
    }

    @Override
    public int read() throws IOException {
      return input.read();
    }
  }
}

Filter class

public class MyFilter implements Filter {
  @Override
  public void doFilter(ServletRequest request, ServletResponse response,
        FilterChain chain) throws IOException, ServletException {

    /* wrap the request in order to read the inputstream multiple times */
    MultiReadHttpServletRequest multiReadRequest = new MultiReadHttpServletRequest((HttpServletRequest) request);

    doMyThing(multiReadRequest.getInputStream());
    chain.doFilter(multiReadRequest, response);
  }
}

Refer these post for more detail

Http Servlet request lose params from POST body after read it once

HttpServletRequestWrapper, example implementation for setReadListener / isFinished / isReady?

Thank you that was super helpful – Shashank Jul 27 '18 at 16:39 — Shashank, Jul 27 '18 at 16:39

How can I modify the object of a post call in filter. Spring boot

1 Answers1