Add Form Verification hibernate-validator in spring boot and display the error message in the freemarker template (recommended ),

Add Form Verification hibernate-validator in spring boot and display the error message in the freemarker template (recommended ),

Create a project

Use IDEA to create a spring-boot project. Select web, validation, and freemarker for dependencies.

First look at the effect

 

Create object class

Create and add annotations. The Code is as follows:

Public class Person implements Serializable {@ NotNull @ Length (min = 3, max = 10) // The Length of username is between 3 and 10 private String username; @ NotNull @ Min (18) // The minimum age is 18 years old. private Integer age; @ NotNull // use the regular expression to verify the field. message: set the verification Failure Information @ Pattern (regexp = "[\ w-\.] + @ ([\ w-] + \\.) + [a-z] {2, 3} ", message =" Incorrect email format ") private String email; public String getEmail () {return email ;} public void setEmail (String email) {this. email = email;} public String getUsername () {return username;} public void setUsername (String username) {this. username = username;} public Integer getAge () {return age;} public void setAge (Integer age) {this. age = age ;}}

Configure controller

Code:

@ Controllerpublic class WebController extends WebMvcConfigurerAdapter {@ Override public void addViewControllers (ViewControllerRegistry registry) {// Add a route and set the Page name registry. addViewController ("/results "). setViewName ("results") ;}@ GetMapping ("/") public String showForm (Person person) {return "form" ;}@ PostMapping ("/") public String checkPersonInfo (@ Valid Person person, BindingResult bindingResult, RedirectAttributes redirectAttributes) {// use BindingResult to verify the correctness of form data if (bindingResult. hasErrors () {// returns the submitted Form content to the page and displays redirectAttributes. addFlashAttribute ("person", person); return "form" ;}return "redirect:/results ";}}

Note: Do not forget the @ Valid annotation

Form page

The form page uses the spring label to retrieve data that fails verification. To use the spring label in spring-boot, you can use spring. the ftl file is placed in resources, and then in application. add the following configuration to yml:

Spring. ftl file path: org.springframework.web.servlet.view.freemarker.spring.ftl

spring: freemarker:  settings:   auto_import: /spring.ftl as spring

Form Page code

<form action="/" method="post"> <div class="form-group">  <label for="username">username</label>  <@spring.bind "person.username"/>  <input type="text" id="username" name="username" value="${person.username!}" class="form-control"      placeholder="username"/>  <span class="text-danger"><@spring.showErrors ""/></span> </div> <div class="form-group">  <label for="age">age</label>  <@spring.bind "person.age"/>  <input type="number" id="age" name="age" value="${person.age!}" class="form-control" placeholder="age"/>  <span class="text-danger"><@spring.showErrors ""/></span> </div> <div class="form-group">  <label for="email">email</label>  <@spring.bind "person.email"/>  <input type="text" id="email" name="email" value="${person.email!}" class="form-control"      placeholder="email"/>  <span class="text-danger"><@spring.showErrors ""/></span> </div> <input type="submit" value="submit" class="btn btn-sm btn-primary"/></form>

Note: you must first use<@spring.bind "person.username"/>Bind the field, and then use<@spring.showErrors ""/> To retrieve the error message.

Reference

Https://spring.io/guides/gs/validating-form-input/

Summary

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