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POWhy is validation not working?
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  1. POWhy is validation not working?
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    copied!<p>I am writing Web app in java using Spring Web MVC framework. Somehow validation does not work. Below is depicted the controller class:</p> <pre><code>@Controller public class UserNameController { @InitBinder() protected void initBinder(WebDataBinder binder) { binder.setValidator(new UserNameValidator()); } // @RequestMapping(value="userName.htm", method=RequestMethod.POST) public String doForm(@ModelAttribute("user") @Valid User user, BindingResult result, Model model) { System.out.println("------------ "+ user.getuName()+" ---------"); if (result.hasErrors()) { System.out.print("===== errors ======"); } model.addAttribute("user",user); return "registration"; } public class UserNameValidator implements Validator { public boolean supports(Class clazz) { System.out.println("========== "+User.class.isAssignableFrom(clazz)+" ==================="); return User.class.isAssignableFrom(clazz); } public void validate(Object target, Errors errors) { System.out.println("======================="); User newUser = (User) target; ValidationUtils.rejectIfEmptyOrWhitespace(errors, "uName", "field.required", "Required field"); if(errors.hasFieldErrors("uName")) { // if(user.existUser() == true) // { //} System.out.print("===== errors 2 ======"); } } } } </code></pre> <p>Method 'supports' is invoked what gives true value, though 'validate' method stays idle. What is the problem?</p> <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt; &lt;beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd"&gt; &lt;context:component-scan base-package="forum.web" /&gt; &lt;bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" /&gt; &lt;/beans&gt; </code></pre> <p>User.java source file:</p> <pre><code>public class User { private String uName; public User(){} public User(String uName) { System.out.println("=== Constructor==== " + uName); this.uName= uName; } public String toString() {System.out.println("=====toString()==== " + uName); return this.uName; } public String getuName() { return uName; } public void setuName(String uName) { this.uName = uName; } } </code></pre> <p>Main part of jsp page:</p> <pre><code>&lt;form id="userName" action="userName.htm" method="post" accept="text/plain" accept-charset="UTF-8" enctype="application/x-www-form-urlencoded"&gt; &lt;td&gt; &lt;label for&gt; User Name: &lt;/td&gt; &lt;td&gt; &lt;/td&gt; &lt;td&gt; &lt;/td&gt; &lt;td&gt; &lt;form:errors path="uName"/&gt; &lt;input type="text" name="uName" maxlength="20" size="40" onmouseout="submitUName()" value="${user}"/&gt; &lt;/p&gt; &lt;/p&gt; &lt;/td&gt; &lt;td&gt;*&lt;/td&gt; &lt;/form&gt; &lt;/tr&gt; </code></pre> <p>This is my updated Controller (new version):</p> <pre><code>@Controller public class UserNameController { private Validator validator; public void setValidator(Validator validator) { this.validator= validator; } @InitBinder("user") protected void initBinder(WebDataBinder binder) { binder.setValidator(new UserNameValidator()); System.out.println("A binder for object: =============== " + binder.getObjectName()); } @RequestMapping(value="userName.htm", method=RequestMethod.POST) public String userName(@ModelAttribute("user") User user, BindingResult result, Model model) { this.validator.validate(user, result); System.out.println("------------ "+ user.getuName()+" ---------"); if (result.hasErrors()) { System.out.print("===== errors ======"); } model.addAttribute("user",user); return "registration"; } public class UserNameValidator implements Validator { public boolean supports(Class clazz) { System.out.println("========== "+User.class.isAssignableFrom(clazz)+" ==================="); return User.class.isAssignableFrom(clazz); } public void validate(Object target, Errors errors) { System.out.println("======================="); User newUser = (User) target; ValidationUtils.rejectIfEmptyOrWhitespace(errors, "uName", "field.required", "Required field"); if(errors.hasFieldErrors("uName")) { // if(user.existUser() == true) // { //} System.out.print("===== errors 2 ======"); } } } } </code></pre> <p>Though for some reasons this line <code>this.validator.validate(user, result);</code> causes NullPointerException. Anyway, 'validate' method is not invoked as above. Best regards</p>
 

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