应用@valid之前的spring mvc进程对象

Question

我有一个如下所示的 spring mvc Controller

@RequestMapping(value="/new", method=RequestMethod.POST)
public String createBooking(@Valid Booking booking, BindingResult bindingResult, Model model, Principal principal)
{
    if(bindingResult.hasErrors()) {
        return "booking/edit";
    }
    //Store Booking in db...
    ...

问题是我从 POST 获取的 Booking 对象是由 Spring 构造的，但无法填充验证器所需的属性之一，因为该属性不存在于表单中。所以我的问题是，有没有办法让我在 @Valid 标记处理程序处理 Booking 之前拦截 Booking 以添加此必需属性？

干杯!网络功能虚拟化

Answer 1

在@Valid触发之前，有两种方法可以修改模型属性对象:

1. 删除 @Valid 并 Autowiring 验证器并手动触发验证器:

class MyController {

  private final Validator validator;

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

  @PostMapping("/new")
  public String createBooking(Booking booking, BindingResult bindingResult, Model model, Principal principal) {
    // edit booking here

    validator.validate(booking, result)

    // original method body here
  }
}

装饰默认验证器并在装饰后的验证器内预处理 booking 对象。

class MyController {

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

  @PostMapping("/new")
  public String createBooking(@Valid Booking booking, BindingResult bindingResult, Model model, Principal principal) {
    ...
  }

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

        public PreProcessBookingValidator(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 Booking) {
                Booking booking = (Booking) target;
                // manipulate booking here

            }

            validator.validate(target, errors);
        }
    }

}

(第二个技巧是我从 https://github.com/spring-projects/spring-framework/issues/11103 中学到的)