# Spring Boot Validation
- [영상 링크](https://youtu.be/b5rzOaDRdyY)
- JSR 380: Bean Validation 2.0
  - https://beanvalidation.org/2.0/spec/
- JSR 303: Bean Validation 1.0
  - https://beanvalidation.org/1.0/spec/

## Form
- Controller
  - `@ModelAttribute`

```java
@PostMapping("/greeting")
public String greetingSubmit(@ModelAttribute Greeting greeting, Model model) {
  model.addAttribute("greeting", greeting);
  return "result";
}
```

```java
public class Greeting {
  private long id;
  private String content;
  // getters and setters
}
```

```html
<form action="#" th:action="@{/greeting}" th:object="${greeting}" method="post">
    <p>Id: <input type="text" th:field="*{id}"/></p>
    <p>Message: <input type="text" th:field="*{content}"/></p>
    <p><input type="submit" value="Submit"/> <input type="reset" value="Reset"/></p>
</form>
```

## Validation

```java
public class PersonForm {

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

	@NotNull
	@Min(18)
	private Integer age;

  // getters and setters
}
```

```java
@PostMapping("/")
public String checkPersonInfo(@Valid PersonForm personForm, BindingResult bindingResult) {
  if (bindingResult.hasErrors()) {
    return "form";
  }
  return "redirect:/results";
}
```

```html
<form action="#" th:action="@{/}" 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>
```

## Validation Annotations JSR380
- `@NotNull`
- `@AssertTrue`
- `@Size`
- `@Min`
- `@Max`
- `@Email`
- `@NotEmpty`: not null, not empty of String, Collection, Map or Array values
- `@NotBlank`: not null or no whitespace
- `@Positive`, `@PositiveOrZero`
- `@Negative`, `@NegativeOrZero`
- `@Past`, `@PastOrPresent`: date value
- `@Future`, `@FutureOrPresent`

```java
List<@NotBlank String> preferences;
```

## ref
- https://www.baeldung.com/javax-validation
- https://spring.io/guides/gs/handling-form-submission/
- https://spring.io/guides/gs/validating-form-input/
- Customize Validation Error Message
  - https://www.baeldung.com/spring-custom-validation-message-source
  - https://www.baeldung.com/javax-validation