Question

In one of my controllers I have:

@RequestMapping(value = "search", method = RequestMethod.GET)
public ModelAndView searchUsers(HttpSession session, HttpServletRequest request) {
    UiUserSearchCriteria userSearchCriteria = (UiUserSearchCriteria) session
            .getAttribute("UsersController_userSearchCriteria");

    if (null == userSearchCriteria) {
        userSearchCriteria= defaultUserSearchCriteria;
    }

    // Here be dragons
    return searchUsers(userSearchCriteria, new BeanPropertyBindingResult(userSearchCriteria,
            "userSearchCriteria"), session, request);
}

@RequestMapping(value = "search", method = RequestMethod.POST)
public ModelAndView searchUsers(
        @ModelAttribute("userSearchCriteria") UiUserSearchCriteria userSearchCriteria,
        BindingResult bindingResult, HttpSession session, HttpServletRequest request) {

    userSearchCriteriaValidator.validate(userSearchCriteria, bindingResult);
    if (bindingResult.hasErrors()) {
        // Here be dragons
        return new ModelAndView("searchUsers");
    }

    ModelAndView result = new ModelAndView("redirect:listUsers");
    PagedListHolder<UiUser> userList = new PagedListHolder<UiUser>(
            usersService.searchUsers(userSearchCriteria));

    userList.setPageSize(10);
    userList.setSort(defaultSort);
    userList.resort();
    session.setAttribute("UsersController_userList", userList);
    session.setAttribute("UsersController_userSearchCriteria", userSearchCriteria);

    return result;
}

The logic is simple: when the user navigates to search page I actually perform a search with default criteria and return him a list (this is the result of requirements changing, huh).

I found a problem in this code, accidentally. When default search criteria is not valid the behavior is: navigate to search -> populate search criteria with invalid criteria -> call another method (the second one, with POST) -> perform validation -> errors are not empty, so return searchUsers view. But the BindingResult bindingResult is actually syntethic, from previous method (new BeanPropertyBindingResult(userSearchCriteria, "userSearchCriteria")). So I got an error No binding result is bound to session (I agree with this).

I cannot have @ModelAttribute and BindingResult parameters (that, which are bound by Spring) pair in GET method to call POST with them.

So what is the best solutions for this?

Answer 1

I think you can simply associate your new BeanPropertyBindingResult(userSearchCriteria,
"userSearchCriteria") with an appropriate Spring model attribute name, this way:

  BindingResult bindingResult = new BeanPropertyBindingResult(userSearchCriteria, "userSearchCriteria")

model.addAttribute(BindingResult.MODEL_KEY_PREFIX + "userSearchCriteria", bindingResult);

This is the default Spring MVC behavior of binding the validation results of a specific model attribute and should help you avoid the No binding result.. error