Replace only selected fields using binding - spring

Question

I'm building simple twitter clone in Spring MVC. I want to provide edit functionality to posted messages.
Message domain object looks like this (simplified)
public class Message {
long id;
String text;
Date date;
User user;
}
I created jps form
<form:form action="edit" method="post" modelAttribute="message">
<table>
<tr>
<td><label for="text">Message: </label></td>
<td><form:textarea path="text" id="text"/></td>
</tr>
<tr>
<td><input type="submit" name="commit" value="Save" /></td>
</tr>
</table>
</form:form>
and added those method in controller class
#RequestMapping(value = "/edit", method = RequestMethod.GET)
public String showEditMessage(#RequestParam long id, Model model) {
Message message = messageService.findMessage(id);
if (message == null) {
return "404";
}
model.addAttribute("message", message);
return "users/editMessage";
}
#RequestMapping(value = "/edit", method = RequestMethod.POST)
public String editMessage(#Valid #ModelAttribute Message message, BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
return "/users/editMessage";
}
messageService.updateMessage(message);
return "/users/editMessage";
}
The problem is that the Message received in editMessage() contains only text field. I assume that this is expected behaviour. Can it be configured to replace fields that are only in jsp form?
I know this is only one field and I could just use #RequestParam String message, but sooner or later I will face similar problem with more than just one field.
I also have side question.
Are attributes added in showEditMessage() are passed to editMessage() method? I tried to add "id" attribute in first method, but I couldn't retrive it using "#RequestParam long id" in second.

Answer 1

#SessionAttributes("message")
On top of controller class solved it.