How to update data in PortalController

Hello, How can I update and delete data from database in Portal Controller using Spring MVC and html form?

This is how I save and show my firstName, lastName list in Controller:

public String add(Model model){
    John john = new John();
    model.addAttribute("john", john);
    return "add";

public String save(Model model, @ModelAttribute("john") John john){

        String firstName = john.getFirstName();
        String lastName = john.getLastName();
        John newJohn = new John(firstName, lastName);

        John standardEntity = metadata.create(John.class);

        return "redirect:/allPersons";

@RequestMapping(value = "/allPersons", method = RequestMethod.GET)
public String getPersons(Model model) {
        LoadContext loadJohn = new LoadContext(John.class);
        loadJohn.setQueryString("select u from test6$John u");
        model.addAttribute("users", dataService.loadList(loadJohn));
        return "list";


Use DataManager’s commit() and remove() methods.