Spring Form Validation
The Need for validation is to check the user input form for
- require fields
- Validate numbers in a range
- validate format (Postal code)
- custom business rule
Java standard bean Validation API
- Java has a standerd Bean validaton API
- Defines metadata model and API for entity validation
- Not tied to either the web tier or the persistence tier
- Available for server-side apps and also client-side javaFx/Swigns apps.
- Spring version 4 and higher supports Bean Validation API
- The preferred method for validation when building the spring app. that means only adding annotations provided by validation API.
- Simply add validation JAR to our Project.
Bean Validation Features:
- Required - to check filed is required
- validate length - to check the length of the input
- Validate numbers -
- Validate with regular expression
- custom validation
Validation Annotation:
- @NotNull - Checks that the annotation value is not null.
- @Min - Must be a number >= value
- @Max - Must be a number <= value
- @Size - Size must match the given size
- @Pattern - Must match a regular expression pattern,
- @Future /@Past - The date must be in the future or past of given
there are so many other annotations
Tricky things with version numbers
Tow release of Hibernate validator
- Hibernate Validator 7 is for Jakarta EE 9 project.
- Hibernate Validator 6.2 is compatible with spring 5.
Hibernate Validator 6.2 has the Same features as HIbernet Validator 7
Setup Hibernate validator in our project
Go to the https://hibernate.org/validator/releases/6.2/
Go to the https://hibernate.org/validator/releases/6.2/
Download the JAR Files
It will start the downloading
Add Validation Rule to customer class
public class Customer {
private String firstName;
@NotNull(message = "is required")
@Size(min=1)
private String lastName;
public String getFirstName() {
return firstName;
}
public String getLastName() {
return lastName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
Display the error message on the HTML form
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Customer Register Form</title>
<style>
.error {color:red}
</style>
</head>
<body>
<form:form action="processForm" modelAttribute="customer">
First Name : <form:input path="firstName" />
<br><br>
Last Name (*) : <form:input path="lastName" />
<form:errors path="lastName" cssClass="error"/>
<input type="submit" value="submit" />
</form:form>
</body>
</html>
Perform validation in the controller class
@Controller
@RequestMapping("/customer")
public class CustomerController {
@RequestMapping("/showForm")
public String showForm(Model theModel) {
theModel.addAttribute("customer",new Customer());
return "customer-form";
}
Create show form jsp file
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<h2>Spring Boot MVC - Home page</h2>
<hr>
<a href="showform">Hello word form</a>
<br><hr>
<a href="customer/showForm">Customer form</a>
</body>
</html>
Add process
@Controller
@RequestMapping("/customer")
public class CustomerController {
@RequestMapping("/showForm")
public String showForm(Model theModel) {
theModel.addAttribute("customer",new Customer());
return "customer-form";
}
@RequestMapping("/processForm")
public String processForm(@Valid @ModelAttribute("customer") Customer theCustomer,
BindingResult theBindingResult) {
if(theBindingResult.hasErrors()) {
return "customer-form";
}else {
return "customer-confirmaton";
}
}
}
Customer confiramtion
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>Customer confirmation</head>
<body>
the customer is conformed : ${customer.firstName} ${customer.lastName} }
</body>
</html>
Output :
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