Java Spring 4 on failed validation, instead of rendering form it simply prints view name

Question

I am from PHP world and trying to learn Java Spring framework in spare time. I was doing good until I decided to add validation to a form. Below is my code.

package com.invokedynamic.spring;


import java.text.DateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;

import javax.validation.Valid;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;
import com.invokedynamic.spring.User;

/**
 * Handles requests for the application home page.
 */
@Controller
public class RestController {

  private static final Logger logger = LoggerFactory.getLogger(RestController.class);
  private Map<String, User> users = new HashMap<String, User>();

  public RestController() {
    // pre-initialize the list of issuers available ...

      users.put("pinkal", new User("pinkal", "pinkal123", "[email protected]", "USA"));
      users.put("mahesh", new User("mahesh", "mahesh123", "[email protected]", "USA"));
  }

  /**
   * Simply selects the home view to render by returning its name.
   */
  @RequestMapping(value = "/", method = RequestMethod.GET)
  public String home(Locale locale, Model model) {
    logger.info("Welcome home! The client locale is {}.", locale);

    Date date = new Date();
    DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, locale);

    String formattedDate = dateFormat.format(date);

    model.addAttribute("serverTime", formattedDate );

    return "status";
  }

  @RequestMapping(value="/users", method=RequestMethod.GET)
  @ResponseBody
  public Map<String, User> getAllUsers() {
    logger.info("Inside getAllUsers() method...");

    return users;
  }

  @RequestMapping(value="/user/{username}", method=RequestMethod.GET)
  @ResponseBody
  public User getUserByUsername(@PathVariable("username") String username) {
      User user = users.get(username);

    if (user != null) {
      logger.info("Inside sgetUserByUsername, returned: " + user.toString());
    } else {
      logger.info("Inside getUserByUsername, ticker: " + username + ", NOT FOUND!");
    }
    return user;
  }

  @RequestMapping(value="/user/delete/{username}", method=RequestMethod.GET)
  @ResponseBody
  public User deleteIssuerByTicker(@PathVariable("username") String username) {
      User user = users.remove(username);

    if (user != null) {
      logger.info("Inside deleteIssuerByTicker, deleted: " + user.toString());
    } else {
      logger.info("Inside deleteIssuerByTicker, ticker: " + username + ", NOT FOUND!");
    }
    return user;
  }

  @RequestMapping(value="/user/create", method=RequestMethod.GET)
  public ModelAndView addUser() {

    return new ModelAndView("addUser", "command", new User());
  }

  @RequestMapping(value="/user/addUser", method=RequestMethod.POST)
  @ResponseBody
  public String addUser(@Valid @ModelAttribute("user") User user, BindingResult result, Model model) {
      if (result.hasErrors()) {           
          return "addUser";
      }
    if (user != null) {
      logger.info("Inside addIssuer, adding: " + user.toString());
    } else {
      logger.info("Inside addIssuer...");
    }
    users.put(user.getUsername(), user);
    return "{\"success\":1}";
  }
}

On failed validation instead of rendering "addUser" view it simply prints "addUser" on screen. What am I doing Wrong? Full source can be seen here.

EDIT

If I remove @ResponseBody from addUser method as suggested by couple of answers below, I get

HTTP Status 500 - java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'command' available as request attribute

Answer 1

This is because you are using @ResponseBody annotation.

When you use this annotation the data returned from here would be treated as data to be present in the body rather then treated as view name and be resolved by the viewResolver.

Also add the below attributes to your form tag as shown below

<f:form method="POST" action="addUser" commandName="user">