on submit, model object returning null

[vikas sharmaa]

I am using Spring 3.0.

I am setting "position" attribute as model object. but, property of position model objects are returning null on submit. how to resolve it?

Please find below the code, with comments:

Model class:

public class MyPosition {

	private Board board;

	private List<User> myList;

	private User user;

               // setter - getter methods
}

Controller class:

public class UserController {

	@RequestMapping(method = RequestMethod.GET)
	public String show(ModelMap model) {

		MyPosition position = new MyPosition();

    position.setBoard(board);
    position.setMyList(myList); // board and myList are processed somewhere else

		model.addAttribute(myList);
		model.addAttribute("position", position);

    // return to jsp view 

	}

	@RequestMapping(method = RequestMethod.POST)
	public String onSubmit(@ModelAttribute("position") MyPosition position, ModelMap model) {

               position.getBoard(); // why this is returning a null value?
               position.getUser(); // why this is returning a null value?

	}

jsp page:

<form:form commandName="position">   
  
<form:radiobuttons path="user" items="${myList}"/>   
 
<input type="submit" value="Submit">

</form:form> 

[vikas sharmaa]

i also tried to add attributes of "position" into model object as follows:

 @RequestMapping(method = RequestMethod.GET)   
    public String show(ModelMap model) {

		model.addAttribute("user", new User());
		model.addAttribute("board", board);
		model.addAttribute(myList);
		model.addAttribute("position", position);
	}

	@RequestMapping(method = RequestMethod.POST)
	public String onSubmit(@ModelAttribute("position") MyPosition position,
						   @ModelAttribute("user") User user,
						   @ModelAttribute("board") Board board,
						   @ModelAttribute("myList") List<User> myList, ModelMap model) {

}

and added the below line in jsp

<form:hidden path="position" />

but this time i am getting below error:

 
org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 2 errors
Failed to convert property value of type 'java.lang.String' to required type 'com.Board' for property 'board'
Failed to convert property value of type 'java.lang.String' to required type 'com.User' for property user'
   

please help.

[vikas sharmaa]

i guess, i required Built-in PropertyEditor implementations to resolve the issue. i am going through the article on spring website http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/validation.html

will get back to here, if not able to resolve the problem.

[vikas sharmaa]

After going through many tutorials on net, i modified my controller class by adding InitBinder as shown below:

Controller class:

@RequestMapping(method = RequestMethod.GET)      
    public String show(ModelMap model) {   
  
        model.addAttribute("user", new User());
        model.addAttribute("board", board);
        model.addAttribute(myList);
        model.addAttribute("position", position);
    }   
  
    @InitBinder
    protected void initBinder(WebDataBinder binder){
		
          binder.registerCustomEditor(User.class, new UserEditor());
          binder.registerCustomEditor(Board.class, new BoardEditor());
    }

    @RequestMapping(method = RequestMethod.POST)   
    public String onSubmit(@ModelAttribute("position") MyPosition position,   
                           @ModelAttribute("user") User user,   
                           @ModelAttribute("board") Board board,   
                           @ModelAttribute("myList") List<User> myList, ModelMap model) {   
  

		System.out.println("user = " + user); // getting default value instead of the bind value 

// process user


		model.addAttribute(user);
		model.addAttribute(board);
		model.addAttribute(myList);
		model.addAttribute("position", position);
}  

i also created UserEditor and BoardEditor classes under the same directory where User and Board class resides. and implemented getAsText and setAsText methods as shown below for UserEditor class:

public class UserEditor extends PropertyEditorSupport {

	public String getAsText() { // converts User into String

		User user = (User) getValue();
		if (user == null) {
			return "";
		}

		return user.getClass().getName() + "," +
			   user.getName() + "," +
			   user.getSalary();
	}

	public void setAsText(String text) throws IllegalArgumentException { // converts String back into User

System.out.println("setAsText user is " + text); // displaying correctly

		String []parts = text.split(",");
		try	{
			User user = (User) Class.forName(parts[0]).newInstance();
			user.setName(parts[1]);
			user.setSalary(Integer.parseInt(parts[2]));
		}
		catch (Exception e) {
			throw new IllegalArgumentException(e);
		}
	}
}

my jsp code, as it is:

<form:form commandName="position">      
     
<form:radiobuttons path="user" items="${myList}"/>      
    
<input type="submit" value="Submit">   
  
</form:form>

the value in path="user" is showing correctly on click of submit button in the setAsText() method of UserEditor class... but this value is not getting copied to model object of the onSubmit method call in controller class...

please help me in resolving it. Thank you.

[vikas sharmaa]

at last, am able to resolve the issues!! i was not calling setValue() inside setAsText() method.