problem in validation

[ganesh pol]

what is the recommended way of error handling(validations) when using the MultiActionController

problem
1]when my login page contains some empty field then it shouild show some
error message

but when flow coming out of the validate mathod of validator

Exception is thrown

as follows

INFO: Using JSP 2.0 ExpressionEvaluator
class com.dss.ems.models.UserModel
i am in support method
class com.dss.ems.models.UserModel
i am in support method
i am in i am in validate method
coming out from validator
20-Dec-2005 09:57:13 org.springframework.web.servlet.FrameworkServlet processRequest
SEVERE: Could not complete request
org.springframework.web.bind.ServletRequestBinding Exception: Errors binding onto object 'command'
at org.springframework.web.bind.ServletRequestDataBin der.closeNoCatch(ServletRequestDataBinder.java:14
5)
at org.springframework.web.servlet.mvc.multiaction.Mu ltiActionController.bind(MultiActionController.ja
va:448)
at org.springframework.web.servlet.mvc.multiaction.Mu ltiActionController.invokeNamedMethod(MultiAction
Controller.java:400)
at org.springframework.web.servlet.mvc.multiaction.Mu ltiActionController.handleRequestInternal(MultiAc
tionController.java:358)
at org.springframework.web.servlet.mvc.AbstractContro ller.handleRequest(AbstractController.java:139)
at org.springframework.web.servlet.mvc.SimpleControll erHandlerAdapter.handle(SimpleControllerHandlerAd



root cause is
org.springframework.validation.BindException: BindException: 2 errors; Field error in object 'command' on field 'userName': rejected value []; codes [UserName kept blank.command.userName,UserName kept blank.userName,UserName kept blank.java.lang.String,UserName kept blank]; arguments []; default message [null]; Field error in object 'command' on field 'userPassword': rejected value []; codes [Password kept blank.command.userPassword,Password kept blank.userPassword,Password kept blank.java.lang.String,Password kept blank]; arguments []; default message [null]
org.springframework.validation.DataBinder.createEr rors(DataBinder.java:126)
org.springframework.validation.DataBinder.<init>(D ataBinder.java:112)
org.springframework.web.bind.WebDataBinder.<init>( WebDataBinder.java:67)



my validation class's methods are

public boolean supports(Class clazz) {
System.out.println(clazz);
System.out.println(" i am in support method ");
return clazz.equals(UserModel.class);
}

public void validate(Object obj,Errors errors){
System.out.println(" i am in i am in validate method ");
UserModel um=(UserModel)obj;

ValidationUtils.rejectIfEmpty(errors,
"userName",Constants.ERROR_MESSAGE_FOR_BLANK_USERN AME);

ValidationUtils.rejectIfEmpty(errors,
"userPassword",Constants.ERROR_MESSAGE_FOR_BLANK_P ASSWORD);

System.out.println("coming out from validator");
}


my jsp page's part

<form method="POST"
action="auth.htm">
<table width="400"
border="0"
cellspacing="5"
cellpadding="0">

<tr>
<spring:hasBindErrors name="usermodel">
<b>invalid UserName/Password </b>
</spring:hasBindErrors >

</tr> <tr>
<td align="right" valign="middle">
<b>Login:</b>
</td>
<td align="left" valign="middle">
<spring:bind path="usermodel.userName">
<input type="text"
name="<c:out value="${status.expression}"/>" value="<c:out value="${status.value}"/>">
</spring:bind>
</td>
</tr>
<tr>
<td align="right" valign="middle">
<b>Password:</b>
</td>
<td align="left" valign="middle">
<spring:bind path="usermodel.userPassword">

<input type="password"
name="<c:out value="${status.expression}"/>" value="<c:out value="${status.value}"/>">

</spring:bind>
</td>
</tr>
<td colspan="2" align="center">
<INPUT type="image"
src="./images/Login.gif"
Onclick="javaScript:submitForm('Login')">
</td>
</table>
</form>


my controller code is

public class LoginController extends MultiActionController implements Controllable {

private Delegatable delegatableProxy=null;

public LoginController() {
System.out.println(" In LoginController ");
}

public void setDelegatableProxy(Delegatable delegatableProxy ) {
this.delegatableProxy=delegatableProxy;
}

public Delegatable getDelegatableProxy() {
return this.delegatableProxy;
}




/*this method is used to dispatch login page to user who wants to acess the system
*
**/
public ModelAndView showLoginPage(HttpServletRequest request,
HttpServletResponse response,
Object obj) throws ServletException {
System.out.println("i am giving login page");
ModelAndView mav=new ModelAndView("login");
mav.addObject("usermodel",new UserModel());
return mav;
}



public ModelAndView authenticateUser( HttpServletRequest request,
HttpServletResponse response,
UserModel command){
System.out.println(" iam in authentication "+command.getClass());
UserModel lc = command;
UserModel um =getDelegatableProxy().authenticateUser( lc.getUserName(),
lc.getUserPassword());


if(um==null) {
System.out.println(" user model is null");
ModelAndView mav=new ModelAndView("login");
mav.addObject("usermodel",new UserModel());

//mav.addObject("ErrorMessage",Constants.ERROR_MESSA GE_FOR_INVALID_USERNAME_PASSWORD);
return mav;
}else {
System.out.println("you are valid user");
return new ModelAndView("Expense");

}
}


}