CODEWITHSUNDEEP
spring-mvchibernate-validator
jax
jax

Reputation: 38573

Possible to modify @ModelAttribute before @Validated is run

Is is possible to modify a @ModelAttribute before it is validated via @Validated.

ie

@RequestMapping(value = "/doSomething", method = RequestMethod.POST)
public final ModelAndView save(
        @Validated(value = {myGroup.class}) @ModelAttribute("myObject") MyObject myObject)

I need to change the state of myObject before @Validated is executed

Upvotes: 1

Views: 1304

Answers (2)

Wim Deblauwe
Wim Deblauwe

Reputation: 26848

There are 2 ways to modify the model attribute object before the @Validated will trigger:

  1. Remove @Validated and autowire the validator and manually trigger the validator:
class MyController {

  private final Validator validator;

  class MyController(Validator validator) {
    this.validator = validator;
  }

  @PostMapping("/doSomething")
  public final ModelAndView save(
        @ModelAttribute("myObject") MyObject myObject, BindingResult result) {
    // edit MyObject here

    validator.validate(myObject, result)

    // original method body here
}
  1. Decorate the default validator and pre-process the myObject object inside the decorated validator.
class MyController {

    @InitBinder
    public void initBinder(WebDataBinder binder) {
        binder.setValidator(new PreProcessMyObjectValidator(binder.getValidator()));
    }

@PostMapping("/doSomething")
  public final ModelAndView save(
        @Validated(value = {myGroup.class}) @ModelAttribute("myObject") MyObject myObject, BindingResult result) {
    ...
  } 

private static class PreProcessMyObjectValidator implements Validator {
        private final Validator validator;

        public PreProcessMyObjectValidator(Validator validator) {
            this.validator = validator;
        }

        @Override
        public boolean supports(@Nonnull Class<?> clazz) {
            return validator.supports(clazz);
        }

        @Override
        public void validate(@Nonnull Object target, @Nonnull Errors errors) {
            if (target instanceof MyObject) {
                MyObject myObject = (MyObject) target;
                // manipulate myObject here

            }

            validator.validate(target, errors);
        }
    }

}

(This second tip is what I picked up from https://github.com/spring-projects/spring-framework/issues/11103)

Upvotes: 0

Yugang Zhou
Yugang Zhou

Reputation: 7283

What about add a ModelAttribute populate method?

@ModelAttribute("myObject")
public MyObject modifyBeforeValidate(
        @ModelAttribute("myObject") MyObject myObject) {
    //modify it here
    return myObject;
}

The side affect is this method will be invoked before every @RequestMapping method if I'm not mistaken.

Update1: example

@ModelAttribute("command")
public ChangeOrderCommand fillinUser(
        @ModelAttribute("command") ChangeOrderCommand command,
        HttpServletRequest request) {
    command.setUser(securityGateway.getUserFrom(request));
    return command;
}

@RequestMapping(value = "/foo/bar", method = RequestMethod.POST)
public String change(@ModelAttribute("command") ChangeOrderCommand command,
        BindingResult bindingResult, Model model, Locale locale) {
}

Upvotes: 1

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