Spring ModelAndView Attribute is null - spring

Question

I have one simple controller and one interceptor.
Within interceptor in postHandle-method I am checking user.
Problem: My user-model is sometimes null, between controller-handles.
postHandle invoked by home-handle==> User-Model is not null
postHandle invoked by check_user-handle ==> User-model is null
postHandle invoked by redirectToErrorPage-handle ==> User-model is
not null anymore and contains everything, what i've expected by
check_user-PostHandle Invocation.
Here is my controller
#Controller
#SessionAttributes("user")
public class HomeController {
#RequestMapping(value = "/", method = RequestMethod.GET)
public ModelAndView home(Model model, HttpServletRequest request, HttpSession session) {
User user = new User();
return new ModelAndView("login", "user", user);
////now User-Model was saved in the session
}
//now i'am redirectring user in the "check_user"-handle
#RequestMapping(value = "/check_user", method = RequestMethod.POST)
public ModelAndView checkUser(#Valid #ModelAttribute("user") User user, BindingResult bindingResult, Model model,
HttpServletRequest request, RedirectAttributes redirectAttr) {
RedirectView redirectView = null;
ModelAndView mav=null;
try {
if(!bindingResult.hasErrors()){
redirectView = new RedirectView("home");
redirectView.setStatusCode(HttpStatus.FOUND);
redirectAttr.addFlashAttribute("httpStatus", HttpStatus.FOUND);
mav = new ModelAndView(redirectView);
return mav; //at next i entry post-handle from interceptor,
//which says to me, that user-model is null.
}
}
//My interceptor redirects me to this handle.
//After this handle within interceptor method "postHandle", i see, that
//user-object exists
#RequestMapping(value = "/error", method = RequestMethod.GET)
public String redirectToErrorPage(HttpServletRequest request){
return "error";
}
}
And my Interceptor:
public class UserInterceptor extends HandlerInterceptorAdapter {
#Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
User user = (User) modelAndView.getModel().get("user");
if(user == null || !user.isAdmin()){
response.sendRedirect(request.getContextPath()+"/failed");
}
}
}
While I retrive, which keys my model has, when postHandle was invoked by "check_user", I have only one key "totalTime". Whats going on with my model?

Answer 1

Try modifying your postHandle() as below:
...
#Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
User user = (User) request.getSession().getAttribute("user");
...