Building Spring MVC application, Controller "Cannot find symbol" Model

Question

I first built my Spring MVC project with gradle bootRun with the following controller class successfully:

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class HelloController {

  @RequestMapping("/")
  public String hello() {
    return "resultPage";
  }
}

Then I changed it to pass data to my view class:

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class HelloController {

  @RequestMapping("/")
  public String hello(Model model) {
    model.addAttribute("message", "Hello from the controller");
    return "resultPage";
  }
}

When I build my project now, I get the following error:

HelloController.java:13: error: cannot find symbol
    public String hello(Model model) {
                        ^
  symbol:   class Model
  location: class HelloController
1 error
:compileJava FAILED

FAILURE: Build failed with an exception.

Any ideas what I'm doing wrong?

Solution

I figured out the problem.

If we want the DispatcherServlet to inject the Model into the function, one of the things we should do is import the Model class.

import org.springframework.ui.Model;

So, I changed my controller class to the following and it worked!

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.ui.Model;

@Controller
public class HelloController {

  @RequestMapping("/")
  public String hello(Model model) {
    model.addAttribute("message", "Hello from the controller");
    return "resultPage";
  }
}

Comments

[sanluck]

Why the author must use it? It fixes the problem?