Concept of Two-Way data binding in Spring MVC - spring

Question

This is my login.jsp file.
<form:form method="POST" action="checklogin" modelAttribute="log">
<form:label path="username">UserName: </form:label>
<form:input path="username" id="username" /><br /><br />
<br />
<form:label path="pswd">Password: </form:label>
<form:password path="pswd" id="password" /><br /> <br />
<br />
<input type="submit" id="btnLogin" value=login class="login" />
</form:form>
This is my controller
#RequestMapping(value = "/checklogin", method=RequestMethod.POST)
public String chklogin(#ModelAttribute Login login, Model mod) {
if (login.getUsername().equals("subro") && login.getpswd().equals("ss")) {
mod.addAttribute("log",login);
return "Home";
}
else {
return "Login";
}
}
Still I am getting the error as
Neither BindingResult nor plain target object for bean name 'log' available as request attribute

Answer 1

Change
#ModelAttribute Login login
To
#ModelAttribute Login log

Answer 2

Two way data binding in spring allows user inputs to be dynamically bound to the beans. It is two-way in a sense that it can get the inputs from the beans and it can post the user inputs to the beans using GET and POST api.
Using the #ModelAttribute annotation you can bind the user inputs with the beans.
#RequestMapping(value = "/login", method=RequestMethod.GET)
public String login(#ModelAttribute Login log){ //one-way binding
return "Login";
}
#RequestMapping(value = "/checklogin", method=RequestMethod.POST)
public String chklogin(#ModelAttribute Login log, Model mod) { //two-way binding
if (login.getUsername().equals("subro") && login.getpswd().equals("ss")) {
mod.addAttribute("log",login);
return "Home";
}
else return "Error";
}
Earlier I haven't written the login method which is mapped with the url /login.
When you are getting an error as "Neither BindingResult nor plain target object for bean name 'log' available as request attribute", it means that the beans ('log' in my case) is not able to bind with the view page.