Validating Form Input

Spring MVC, Sptring boot/spring-io-guides

Validating Form Input

고인돌개발자 2021. 8. 22. 23:54

Spring guide (스프링 가이드 실습) https://spring.io/guides/gs/validating-form-input/

▶ 학습목표
1. 멤버변수를 갖는 클래스를 파라메터로 하여 템플릿코드에 해당 클래스의 값을 사용하도록 한다.
2. @Valid 어노테이션을 통해 파라메터값의 validation 을 체크하도록 한다.

▶ Dependency - build.gradle

plugins {
id 'org.springframework.boot' version '2.5.4'
id 'io.spring.dependency-management' version '1.0.11.RELEASE'
id 'java'
}

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'

repositories {
mavenCentral()
}

dependencies {
implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
implementation 'org.springframework.boot:spring-boot-starter-validation'
implementation 'org.springframework.boot:spring-boot-starter-web'
testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

test {
useJUnitPlatform()
}

▶ 자바코드
1. Controller
2. 멤버변수를 갖는 클래스 , validation 체크 진행

package com.example.spring;

import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import javax.validation.Valid;

@Controller
public class WebController implements WebMvcConfigurer {

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/results").setViewName("results");
    }

    @GetMapping("/form")
    public String showForm(PersonForm personForm) {
        /*
           PersonForm 클래스를 파라메터로 하여, form.html 에서 해당 클래스를 사용할 수 있도록 해준다.
         */
        System.out.println("form1");
        return "form";
    }

    @PostMapping("/form")
    public String checkPersonInfo(@Valid PersonForm personForm, BindingResult bindingResult) {
        /*
           PersonForm 클래스를 파라메터로 하며, 해당 파라메터의 validation 체크를 하도록 한다.
           validation 체크의 결과는 BindingResult 를 사용하며,
           해당값이 오류가 있을경우  form.html 에 오류를 전달한다.
         */

        System.out.println("form2");
        if (bindingResult.hasErrors()) {
            return "form";
        }

        return "redirect:/results";
    }
}

package com.example.spring;

import javax.validation.constraints.Min;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

public class PersonForm {

    @NotNull
    @Size(min = 2, max = 30)
    private String name="Hong";

    @NotNull
    @Min(18)
    private Integer age=30;

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

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

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String toString() {
        return "Person(Name: " + this.name + ", Age: " + this.age + ")";
    }
}

▶ templates (Thymeleaf)
1. form.html
2. results.html

form.html

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<body>
<form action="#" th:action="@{/form}" th:object="${personForm}" method="post">
  <table>
    <tr>
      <td>Name:</td>
      <td><input type="text" th:field="*{name}" /></td>
      <td th:if="${#fields.hasErrors('name')}" th:errors="*{name}">Name Error</td>
    </tr>
    <tr>
      <td>Age:</td>
      <td><input type="text" th:field="*{age}" /></td>
      <td th:if="${#fields.hasErrors('age')}" th:errors="*{age}">Age Error</td>
    </tr>
    <tr>
      <td><button type="submit">Submit</button></td>
    </tr>
  </table>
</form>
</body>
</html>

results.html

<html>
<body>
Congratulations! You are old enough to sign up for this site.
</body>
</html>

▶ 실행화면