Java, Spring Framework MVC - redirection

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, controller returns string

"redirect:entryView/"+comment.getEntryId();

And everything is okay.

But when there are some errors, if controller returns

"redirect:entryView/"+comment.getEntryId();

The errors should be displaed near the form with spring-form.tld tags:

<form:errors path="author"/>

But there are no displayed errors! When i am trying to return

"entryView/"+comment.getEntryId();

Without redirect: prefix, then it is going to /rus/WEB-INF/jsp/entryView/8.jsp and there is HTTP Status 404. But it must go to http://example.com/rus/entryView/8, i.e page where the article and form for comments are!

This is view resolver:

<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <开发者_StackOverflow社区property name="suffix" value=".jsp"/>
</bean>

What should i do?

Rest of controller:

@Controller
public class CommentController {
private RusService rusService;
private CommentValidator commentValidator;
@Autowired
public CommentController(RusService rusService,CommentValidator commentValidator){
    this.rusService = rusService;
    this.commentValidator = commentValidator;
}
@RequestMapping(value="/addComment",method=RequestMethod.POST)
public String addComment(Comment comment,BindingResult result){
    commentValidator.validate(comment, result);
    if(result.hasErrors()){
        return "redirect:entryView/"+comment.getEntryId();
    }else{
        rusService.postComment(comment);
        return "redirect:entryView/"+comment.getEntryId();
    }
}
}

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).

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...

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));
}