Java, Spring Framework MVC - redirection

Question

I am using spring framework 3. I have a form for posting comments to the article. When the form is submitted, it is checked if there any errors. In case there is no errors, cont

Answer 1

bkent314 is right:

Have a look at this two method that is a way that defently works. I separate domain objects from form gui objects (FolderCreateCommand) but that is my style. And in this case I use ModelAndView for return instead of string, because so I have full controll to the model.

@RequestMapping(method = RequestMethod.GET, params = "form")
public ModelAndView createForm() {
    return modelAndViewForCreate(new FolderCreateCommand(..default values..));
}

@RequestMapping(method = RequestMethod.POST)
public ModelAndView create(@Valid FolderCreateCommand folderCreateCommand,
          BindingResult bindingResult) {

    if (bindingResult.hasErrors()) {
        return modelAndViewForCreate(folderCreateCommand);
    }
    Folder folder = this.folderService.createFolder(folderCreateCommand);
    return redirectToShow(folder);
}


private ModelAndView modelAndViewForCreate(FolderCreateCommand folderCreateCommand) {
    ModelMap uiModel = new ModelMap();
    uiModel.addAttribute("folderCreateCommand", folderCreateCommand);
    uiModel.addAttribute("parentFolders", this.folderDao.readAll());
    return new ModelAndView("folders/create", uiModel);
}

private ModelAndView redirectToShow(Folder folder) {
    return new ModelAndView(new RedirectView("/folders/" + folder.getId(), true));
}

Answer 2

Try using the view of the page of the "add comment" form instead of redirecting to the view that displays the new comment:

if(result.hasErrors()) {
    return "commentForm";
}

You may also have to add @ModelAttribute Comment in the method signature...

Answer 3

The display of errors in <form:errors path="author"/> works like this:

• During validation/binding, the Errors are saved as an attribute in the HttpServletResponse object
• The implementation of this JSP tag calls response.getAttribute(name) to find the Errors instance to display

When you use redirect:url, you are instructing Spring to send a 302 Found to the client's browser to force the browser to make a second request, to the new URL.

Since the redirected-to page is operating with a different set of request/response objects, the original Errors is lost.

The simplest way to pass "errors" to a page you want to redirect to in order for the new page to display it would be to handle it yourself, by adding a message to the Session object which the second page's controller can look at (or by passing an argument in the URL).