Question

With ModelAttribute annotation, we can feed many thing like listbox.

Is it better to feed each lisbox with a different method in the controler or to use a form and have a list of object for every listbox?

Answer 1

If the controller class is used for different requests where some have this listboxes and some not, (for example the Controller handles the show, create and update functions for an entity, where only the create and update pages have that list boxes) then popluating the model with the @ModelAttribute annotated method would mean, that this methods will be executed even if there values are not needed. — I my humble opinnion this would be bad.

I hope I understand your question right, if not please add a example for each of the two choises you want to compare.

@RequestMapping("/users")
@Controller
TheWayIPreferController() {

@RequestMapping(params = "form", method = RequestMethod.GET)
public ModelAndView createForm() {
  ModelMap uiModel = new ModelMap();
  uiModel.addAttribute("userCreateCommand", new UserCreateCommand());
  uiModel.addAttribute("securityRoles", this.securityRoleDao.readAll()));
  uiModel.addAttribute("salutations", this.salutationDao.readAll()));
  uiModel.addAttribute("locales", this.localeDao.readAll());
  return new ModelAndView("users/create", uiModel);
}

@RequestMapping(method = RequestMethod.POST)
public ModelAndView create(final @Valid UserCreateCommand userCreateCommand, final BindingResult bindingResult) {
...
}


@RequestMapping(value = "/{id}", method = RequestMethod.GET)
public ModelAndView show(@PathVariable("id") final User user) {
...
}
}

instead of:

@RequestMapping("/users")
@Controller
TheWayIDiscourageController(){


@ModelAttribute("securityRoles")
public List<SecurityRoles> getSecurityRoles(){
   return this.securityRoleDao.readAll();
}

@ModelAttribute("salutations")
public List<SecurityRoles> getSalutations(){
   return this.salutationDao.readAll());
}

@ModelAttribute("locales")
public List<SecurityRoles> getLocals(){
   return this.localeDao.readAll();
}

@RequestMapping(params = "form", method = RequestMethod.GET)
public ModelAndView createForm() {
  return new ModelAndView("users/create", "userCreateCommand", new UserCreateCommand());
}

@RequestMapping(method = RequestMethod.POST)
public ModelAndView create(final @Valid UserCreateCommand userCreateCommand, final BindingResult bindingResult) {
...
}

@RequestMapping(value = "/{id}", method = RequestMethod.GET)
public ModelAndView show(@PathVariable("id") final User user) {
...
}
}