验证Thymeleaf中的输入 [英] validate input in Thymeleaf

问题描述

我有这个输入:

Masa: <input type="number"  class="form-control form-text"   name="masa"/>
    <div class="text col-sm-12 error" th:if="${wzrost}" >
        <p class="text text-center">
            To pole jest wymagane
        </p>
    </div>
    Wzrost: <input type="number" class="form-control form-text "   name="wzrost"/>
    <div class="text col-sm-12 error" th:if="${wzrost}" >
        <p class="text text-center">
            To pole jest wymagane
        </p>
    </div>

还有这个控制器；

String x = String.valueOf(masa);
        String y = String.valueOf(wzrost);


        if(x==null ){
        model.addAttribute("wzrost",true);
        return"views/success";
    }
        if(y==null ){
            model.addAttribute("wzrost",true);
            return"views/success";
        }

当我单击表单提交按钮时，总是出现错误nullpointerexception.

When I click form submit button I always get error nullpointerexception.

如何验证输入，以便在输入为空时弹出消息

How do I validate input, so that when it is empty the message pops up

推荐答案

似乎您要实现服务器端验证.为此，最好的方法是使用验证器及其bindingResult.实施服务器端验证的步骤是

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. 需要模型

1. Have for model

public class PersonForm {
  private String name;

 public String getName() {
    return this.name;
}

 public void setName(String name) {
    this.name = name;
}
}

在html中使用表单模型

Use form model in html

<form action="#" th:action="@{/personForm}" th:object="${personForm}" method="post">
<table>
    <tr>
        <td><label th:text="#{label.name}+' :'"></label></td>
        <td><input type="text" th:field="*{name}" /></td>
        <td th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Generic Error</td>
    </tr>
    <tr>
        <td><button type="submit">Submit</button></td>
    </tr>
</table>
</form>

1. 具有验证器类

@Component

@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");
    }
}}

1. 将验证器绑定到控制器，然后让spring做魔术.

@Controller

@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";
}
}

这篇关于验证Thymeleaf中的输入的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！