How to receive JSON data with relation to existing master record in Spring MVC/REST creation

I am new in Spring MVC / REST. My aim is to create REST endpoint that provide CRUD features and will be utilized by AngularJS. I faced problem when trying to handle creation of new Entity that has relation to other existing record that provided by HTML select (by its id).

@Entity
@Table(name="goal")
public class Goal {

    private String title;

    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name="categoryId")
    private Category category;

    //getter setter ommited
}

@Entity
@Table(name="category") 
public class Category {

    private Long id;
    private String name;

    //getter setter ommited
}

//Controller
@RequestMapping(value = "/goals", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
@ResponseStatus(HttpStatus.CREATED)
public MasterGoal create(@RequestBody Goal goal) {
  goal = masterGoalService.saveGoal(goal);
  return goal;
}

And here is the JSON from Angular:

//assumed that categoryId: 1 -> "Personal", already exist in the database 
{
  "title": "My Goal",
  "categoryId": 1
}

This did not work. I also try to implement the suggestion from here, but it didn't work either. the conversion process wasn't triggered.

public class CategoryEditor extends PropertyEditorSupport {

    private CategoryRepository repo;


    public CategoryEditor(CategoryRepository repo) {
        this.repo = repo;
    }

    @Override
    public String getAsText() {
        return super.getAsText();
    }

    @Override
    public void setAsText(String text) throws IllegalArgumentException {
        Category category = null;

        try {
            Long id = (long) Integer.parseInt(text);
            category = repo.findOne(id);            
        } catch (NumberFormatException e) {
            logger.debug("*** " + e.getMessage());
        } catch (Exception e) {
            logger.debug("*** " + e.getMessage());
        }

        this.setValue(category);
    }

}

//In Controller
@InitBinder
protected void initBinder(HttpServletRequest request, ServletRequestDataBinder binder) {
    binder.registerCustomEditor(Category.class, new CategoryEditor(categoryRepo));
}

Are there any best practice to handle this kind of issue?