BAEL-112 | Spring MVC Validation - a Custom Validator (#934)

* BAEL-112 | Spring MVC Validation - a Custom Validator

### Implementation of a custom validator in Employee class using
Validator interface

* BAEL-112 | Spring MVC Validation - a Custom Validator

Implementation of a custom validator in Employee class using Validator
interface

* BAEL-112 | Spring MVC Validation - a Custom Validator

Reverting changes made for a previous module

* BAEL-112 | Spring MVC Validation - a Custom Validator

Reverting changes to module ‘spring-mvc-java’

* BAEL-112 | Spring MVC Validation - a Custom Validator

Reverting changes to module ‘spring-mvc-java’

* BAEL-112 | Spring MVC Validation - a Custom Validator

Final reversion of changes to previous module used

* BAEL-112 | Spring MVC Validation - a Custom Validator

formats the EmployeeValidator class

* BAEL-112 | Spring MVC Validation - a Custom Validator

Modification from @RequestMapping POST to @PostMapping as per Final
Review

* BAEL-112 | Spring MVC Validation - a Custom Validator

Reverts the changes made to Employee and Employee Controller. Created a
new class, Customer as implementation for custom validation

* BAEL-112 | Spring MVC Validation - a Custom Validator

Reverting EmployeeController

* BAEL-112 | Spring MVC Validation - a Custom Validator

Reverting EmployeeHome

spring-mvc-forms/src/main/java/com/baeldung/springmvcforms/controller/CustomerController.java

@@ -0,0 +1,42 @@
+package com.baeldung.springmvcforms.controller;
+
+import javax.validation.Valid;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.ModelMap;
+import org.springframework.validation.BindingResult;
+import org.springframework.web.bind.annotation.ModelAttribute;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.servlet.ModelAndView;
+
+import com.baeldung.springmvcforms.domain.Customer;
+import com.baeldung.springmvcforms.validator.CustomerValidator;
+
+@Controller
+public class CustomerController {
+
+    @Autowired
+    CustomerValidator validator;
+
+    @RequestMapping(value = "/customer", method = RequestMethod.GET)
+    public ModelAndView showForm() {
+        return new ModelAndView("customerHome", "customer", new Customer());
+    }
+
+    @PostMapping("/addCustomer")
+    public String submit(@Valid @ModelAttribute("customer") final Customer customer, final BindingResult result, final ModelMap model) {
+        validator.validate(customer, result);
+        if (result.hasErrors()) {
+            return "customerHome";
+        }
+        model.addAttribute("customerId", customer.getCustomerId());
+        model.addAttribute("customerName", customer.getCustomerName());
+        model.addAttribute("customerContact", customer.getCustomerContact());
+        model.addAttribute("customerEmail", customer.getCustomerEmail());
+        return "customerView";
+    }
+
+}

spring-mvc-forms/src/main/java/com/baeldung/springmvcforms/domain/Customer.java

@@ -0,0 +1,45 @@
+package com.baeldung.springmvcforms.domain;
+
+public class Customer {
+    private String customerId;
+    private String customerName;
+    private String customerContact;
+    private String customerEmail;
+
+    public Customer() {
+        super();
+    }
+
+    public String getCustomerId() {
+        return customerId;
+    }
+
+    public void setCustomerId(String customerId) {
+        this.customerId = customerId;
+    }
+
+    public String getCustomerName() {
+        return customerName;
+    }
+
+    public void setCustomerName(String customerName) {
+        this.customerName = customerName;
+    }
+
+    public String getCustomerContact() {
+        return customerContact;
+    }
+
+    public void setCustomerContact(String customerContact) {
+        this.customerContact = customerContact;
+    }
+
+    public String getCustomerEmail() {
+        return customerEmail;
+    }
+
+    public void setCustomerEmail(String customerEmail) {
+        this.customerEmail = customerEmail;
+    }
+
+}

spring-mvc-forms/src/main/java/com/baeldung/springmvcforms/validator/CustomerValidator.java

@@ -0,0 +1,28 @@
+package com.baeldung.springmvcforms.validator;
+
+import org.springframework.stereotype.Component;
+import org.springframework.validation.Errors;
+import org.springframework.validation.ValidationUtils;
+import org.springframework.validation.Validator;
+
+import com.baeldung.springmvcforms.domain.Customer;
+
+@Component
+public class CustomerValidator implements Validator {
+
+    @Override
+    public boolean supports(Class<?> clazz) {
+        return Customer.class.isAssignableFrom(clazz);
+    }
+
+    @Override
+    public void validate(Object target, Errors errors) {
+
+        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "customerId", "error.customerId", "Customer Id is required.");
+        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "customerName", "error.customerName", "Customer Name is required.");
+        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "customerContact", "error.customerNumber", "Customer Contact is required.");
+        ValidationUtils.rejectIfEmptyOrWhitespace(errors, "customerEmail", "error.customerEmail", "Customer Email is required.");
+
+    }
+
+}

spring-mvc-forms/src/main/webapp/WEB-INF/views/customerHome.jsp

@@ -0,0 +1,47 @@
+<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
+<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
+<html>
+<head>
+<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
+<title>Form Example - Add Customer</title>
+<style>
+.error {
+	color: #ff0000;
+	font-weight: bold;
+}
+</style>
+</head>
+<body>
+	<h3>Welcome, Enter The Customer Details</h3>
+
+	<form:form method="POST" action="${pageContext.request.contextPath}/addCustomer" modelAttribute="customer">
+		<table>
+			<tr>
+				<td><form:label path="customerId">Customer Id</form:label></td>
+				<td><form:input path="customerId" /></td>
+				<td><form:errors path="customerId" cssClass="error" /></td>
+			</tr>
+			<tr>
+				<td><form:label path="customerName">Customer Name</form:label></td>
+				<td><form:input path="customerName" /></td>
+				<td><form:errors path="customerName" cssClass="error" /></td>
+			</tr>
+			<tr>
+				<td><form:label path="customerContact">Customer Contact</form:label></td>
+				<td><form:input path="customerContact"/></td>
+				<td><form:errors path="customerContact" cssClass="error" /></td>
+			</tr>
+			<tr>
+				<td><form:label path="customerEmail">Customer Email</form:label></td>
+				<td><form:input path="customerEmail" /></td>
+				<td><form:errors path="customerEmail" cssClass="error" /></td>
+			</tr>
+			<tr>
+				<td><input type="submit" value="Submit" /></td>
+			</tr>
+		</table>
+	</form:form>
+
+</body>
+
+</html>

spring-mvc-forms/src/main/webapp/WEB-INF/views/customerView.jsp

@@ -0,0 +1,28 @@
+<%@taglib uri="http://www.springframework.org/tags/form" prefix="form"%>
+<html>
+<head>
+<title>Spring MVC Form Handling</title>
+</head>
+<body>
+
+	<h2>Submitted Customer Information</h2>
+	<table>
+		<tr>
+			<td>Customer Id :</td>
+			<td>${customerId}</td>
+		</tr>
+		<tr>
+			<td>Customer Name :</td>
+			<td>${customerName}</td>
+		</tr>
+		<tr>
+			<td>Customer Contact :</td>
+			<td>${customerContact}</td>
+		</tr>
+		<tr>
+			<td>Customer Email :</td>
+			<td>${customerEmail}</td>
+		</tr>
+	</table>
+</body>
+</html>