Objects binding in Spring MVC form

Question

I'm working on a test application using Spring MVC. I have a `Person` class and a `Group` class. Every `Person` object references a `Group` object. Now I implemented a jsp that show Person data and allow editing. Inside my form i put a select control to select the pearson's group: ``` ``` It shows the correct group when I load the page, but I cannot save changes, because in the controller I get only the string representing the group id. So, my question is: how can I obtain a `Group` object instead of its id in my controller? UPDATE Here my controller code: ``` @RequestMapping(value = "/details", params = "save", method = RequestMethod.POST) public String save(@ModelAttribute("person") Person p, BindingResult result) { this.personManager.savePerson(p); return "redirect:/people/details?id=" + p.getId(); } ```

Accepted Answer

Create your own GroupEditor (that will populate the group object instance correcty) by extending PropertyEditorSupport. Then bind that in your controller :

```
@InitBinder
protected void initBinder(WebDataBinder binder)     {
      binder.registerCustomEditor(Group.class, new GroupEditor(groupService));
}
```

and your actual editor could look somethign like this :

```
public class GroupEditor extends PropertyEditorSupport{

private final GroupService groupService;

public GroupEditor(GroupService groupService){
        this.groupService= groupService;
    }

@Override
    public void setAsText(String text) throws IllegalArgumentException {
      Group group = groupService.getById(Integer.parseInt(text));
      setValue(group);
    }
}
```

Spring docs

Objects binding in Spring MVC form

Solution

Problem