validate input in Thymeleaf

Question

I have this input:

Masa: 
    


        
      

Answer 1

It seems like you want to implement server side validation. For this the best approach is to use validators and its bindingResult. Steps to implement server side validation is

1. Have for model

   public class PersonForm {
     private String name;
   
    public String getName() {
       return this.name;
   }
   
    public void setName(String name) {
       this.name = name;
   }
   }
   

2. Use form model in html

   
   
       
   
           
   
           
   
           
   Generic Error
       
       
   
           
   Submit
       
   
   
   

   3. Have validator class

   @Component

   public class PersonFormValidator implements Validator {
   @Override
   public boolean supports(Class clazz) {
       return PersonForm.class.equals(clazz);
   }
   
   @Override
   public void validate(Object target, Errors errors) {
       ValidationUtils.rejectIfEmpty(errors, "name", "field.name.empty");
       PersonForm p = (PersonForm) target;
   
       if (p.getName().equalsIgnoreCase("XXX")) {
           errors.rejectValue("name", "Name cannot be XXX");
       }
   }}
   

   4. Bind validator to controller and let spring do the magic.

   @Controller

   public class WebController {
   @Autowired
   PersonFormValidator personFormValidator;
   
   
   @InitBinder("personForm")
   protected void initPersonFormBinder(WebDataBinder binder) {
   binder.addValidators(personFormValidator);
   }
   
   @PostMapping("/personForm")
   public String checkPersonInfo(@Validated PersonForm personForm, BindingResult bindingResult, final RedirectAttributes redirectAttributes) {
   if (bindingResult.hasErrors()) {
       return "personForm";
   }
   redirectAttributes.addFlashAttribute("personResult",  apiClientService.getPersonResult(personForm));
   return "redirect:/spouseForm";
   }
   }