Passing an object from view to controller - spring-mvc

Question

I want to add new message to database from my .jsp inputs via controller. I tried to just create new object of message in controller and put it in database and it works fine. But when I try to do it using inputs i receive error like this:
SEVERE [http-nio-8080-exec-2]org.springframework.web.servlet.tags.form.InputTag.doStartTag Neither BindingResult nor plain target object for bean name 'message' available as request attribute
java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'message' available as request attribute
My code:
#Controller
public class DemoController {
#Autowired
UserService userService;
#Autowired
MessageService messageService;
#PostMapping("/messages/sendNewMessage")
public String sendNewMessage(#ModelAttribute("message") MessagesEntity tempMessage) {
Authentication auth = SecurityContextHolder.getContext().getAuthentication();
tempMessage.setFromUsername(userService.getUser(auth.getName()));
messageService.sendNewMessage(tempMessage);
return "redirect:/messages";
}
}
JSP here
<form:form action="sendNewMessage" modelAttribute="message" method="POST">
<table>
<tbody>
<tr>
<td><label>Username:</label></td>
<td><form:input path="toUsername" /></td>
</tr>
<tr>
<td><label>Subject:</label></td>
<td><form:input path="subject" /></td>
</tr>
<tr>
<td><label>Content:</label></td>
<td><form:input path="content" /></td>
</tr>
<tr>
<td><label></label></td>
<td><input type="submit" value="Send" class="save" /></td>
</tr>
</tbody>
</table>
</form:form>

Answer 1

you are using action url as sendNewMessage in jsp view but in the controller, it is /messages/sendNewMessage.

Answer 2

You need to put MessagesEntity object in ModelAttribute.
Either define the ModelAttribute while loading the form page like below.
#RequestMapping(value = "/", method = RequestMethod.GET)
public String messageForm(Model model) {
model.addAttribute("message", new MessagesEntity());
return "messageFormPageName";
}
or Put below method in the controller which will be common for complete controller so ModelAttribute will be available always.
#ModelAttribute("message")
public MessagesEntity createModel() {
return new MessagesEntity();
}