Same form in multiple locations in Thymeleaf 3 & Spring 4 - spring

Question

I'd like to have my login form (for example) on multiple pages, and I want to pre-populate it with the current user's login (assuming that user is recognized via cookie). But I don't want every controller method for every possible page to have to provide a LoginForm bean for the form. I do want all the validation magic when the form is submitted, and then of course I want the result of the form to the same page the user was on when they submitted it.
I can't quite figure out how to accomplish this right now. Is it even possible?
EDIT:
I've got a Thymeleaf form like this:
<form action="#" data-th-action="#{/users/login}" data-th-object="${loginForm}" method="post">
<input type="text" placeholder="Email or Username" data-th-field="${loginForm.login}">
<input type="password" placeholder="Password" data-th-field="${loginForm.password}">
<button type="submit" name="login">Sign in</button>
<button type="submit" name="register">Register</button>
</form>
If I don’t create a LoginForm (my class) bean and stick it in the model under loginForm, then I get an exception on GET, when rendering the page.

Answer 1

You don't need to pass the LoginForm to multiple controllers, rather, you can centralize your code at a single place with a http filter by validating the Login form for the required urls as below:
LoginFormValidationFilter class:
#Component
public class LoginFormValidationFilter implements Filter {
#Override
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
String url = request.getRequestURL();
if(url.equals(YOUR_LOGIN_URL)) {
//validate the request here for the required urls
//If request is invalid, send an error message back
}
chain.doFilter(req, res);
}
#Override
public void init(FilterConfig filterConfig) {
}
#Override
public void destroy() {
}
}
Web.xml filter mapping:
<filter>
<filter-name>LoginFormValidationFilter </filter-name>
<filter-class>xyz.LoginFormValidationFilter </filter-class>
</filter>
<filter-mapping>
<filter-name>LoginFormValidationFilter </filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>