@ModelAttribute

[Shahid Pathan]

I have runnung example with @ModelAttribute in method param as follows

@Controller
@RequestMapping("login")
public class LoginControllerTest {
	//------------------------------ Working fine -----------------------------------
	@RequestMapping(value = "dologin.htm", method = RequestMethod.GET)
	public String getLoginpage(@ModelAttribute LoginForm loginForm,
			BindingResult result) {
		return "loginform1";
	}
	@RequestMapping(value = "dologin.htm", method = RequestMethod.POST)
	public String doLoginpage(@Valid @ModelAttribute LoginForm loginForm,
			BindingResult result, ModelMap model) {
		if(result.hasErrors()){
			return getLoginpage(loginForm, result);
		}
		model.addAttribute("message", loginForm.getUserName() + "-" + loginForm.getPassword());
		return "helloworld";
	}
	

I have just created one more class LoginFormDto as same like LoginForm (you can say duplicate class) and add 2 more method in same controller

	@RequestMapping(value = "dologin1.htm", method = RequestMethod.GET)
	public String getLoginpage1(@ModelAttribute LoginFormDto loginForm,
			BindingResult result) {
		return "loginform1";
	}
	@RequestMapping(value = "dologin1.htm", method = RequestMethod.POST)
	public String doLoginpage1(@Valid @ModelAttribute LoginFormDto loginForm,
			BindingResult result, ModelMap model) {
		if(result.hasErrors()){
			return getLoginpage1(loginForm, result);
		}
		model.addAttribute("message", loginForm.getUserName() + "-" + loginForm.getPassword());
		return "helloworld";
	}

When I hit url for dologin1.htm (GET) i am getting following error
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'loginForm' available as request attribute

Everything work fine for url dologin.htm

I am not getting what exactly i am missing?

Can anyone please point me...

[Shahid Pathan]

Now I got it why it was not working.
Following is my understanding about the above example.
I did not specified name for ModelAttribute ie(something like @ModelAttribute("loginForm")) . So the container assume name as a Class Name ( first character small)
for example
@ModelAttribute LoginForm => @ModelAttribute("loginForm")

In my second example i used @ModelAttribute LoginFormDto so the container by default looking for
attribute "loginFormDto" not for "loginForm"

If I give explicitly attribute name with ModelAttribute it works without any issue.

I dont know if this is documented somewhere.