Unable to repopulate values after xml validation in Struts2

Question

I was recently working with a login page with Struts2 framework and for validating the fields i used XML Validation feature provided by Struts2. And the fields are validated but the problem is that, if any of the field is not empty after validation the those field values are not repopulated in the corresponding field.The Example code is given.The version of the framework is 2.5.x.

Login.jsp

<s:form method="post" action="authenticate">
    <div class="form-group">
        <span class="input-icon"> 
                <s:textfield name="strUserName" id="strUserName" cssClass="form-control" placeholder="Username or Email"></s:textfield> 
                <i class="fa fa-user"></i>
                </span> 
                <span>
                    <s:fielderror fieldName="strUserName"/>
                </span>
                </div>
        <div class="form-group">
           <span class="input-icon"> 
                <s:password name="strPassword" id="strPassword" cssClass="form-control" placeholder="Password"></s:password> <i class="fa fa-lock"></i>
           </span> 
            <span>
                <s:fielderror fieldName="strPassword"/>
            </span>
        </div>
</s:form>

struts.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.5//EN"
    "http://struts.apache.org/dtds/struts-2.5.dtd">
<struts>
    <constant name="struts.enable.DynamicMethodInvocation" value="false" />   
    <constant name="struts.action.extension" value=",json"/>

    <!--    Set to false before deploying the application -->
    <constant name="struts.devMode" value="true" /> 
    <constant name="struts.enable.SlashesInActionNames" value="true"/>
    <constant name="struts.mapper.alwaysSelectFullNamespace" value="false"/>

    <constant name="struts.configuration.xml.reload" value="false" />
    <!-- constant to define global resource bundle -->
    <constant name="struts.custom.i18n.resources" value="globalMessages" />
    <constant name="struts.ui.theme" value="simple" />

<package name="<package_name>" namespace="/" extends="struts-default">
<action name="authenticate" class="<Action_class_name>" method="<method_name>">
            <interceptor-ref name="store">
                <param name="operationMode">STORE</param>
            </interceptor-ref>
            <interceptor-ref name="defaultStack" />
            <result type="redirectAction">Successpage</result>
            <result name="input" type="redirectAction">login</result>
</action>   
<action name="login">
            <interceptor-ref name="store">
                <param name="operationMode">RETRIEVE</param>
            </interceptor-ref>
            <result>login.jsp</result>
</action>
</package>
</struts>

Action_name-validation.xml

<!DOCTYPE validators PUBLIC "-//Apache Struts//XWork Validator 1.0.3//EN"
        "http://struts.apache.org/dtds/xwork-validator-1.0.3.dtd">
<validators>
 <validator type="requiredstring">
    <param name="fieldname">strUserName</param>
    <param name="trim">true</param>
    <message key="errors.required"></message>
 </validator>
  <validator type="requiredstring">
    <param name="fieldname">strPassword</param>
    <param name="trim">true</param>
    <message key="errors.required"></message>
 </validator>
</validators>

Action_name.java

public class Action_name extends ActionSupport implements ModelDriven<UserModel> {
    private UserModel user;

    public String method_name() {
     if(success){
        return SUCCESS;
     }else{
       return INPUT;
     }
    }
    @Override
    public UserModel getModel() {
        user = new UserModel();
        return user;
    }
}

Applicatin - intial run

Application - After Validation

value "xyz" is not repopulated after the validation.

Answer 1

There are two problems:

1. your login action

   <action name="login">
       <interceptor-ref name="store">
           <param name="operationMode">RETRIEVE</param>
       </interceptor-ref>
       <result>login.jsp</result>
   </action>
   

   has only a single interceptor, the MessageStore one.

   It should have instead at least the ModelDriven and the Parameters Interceptors to work correctly. For example

   <action name="login">
       <interceptor-ref name="store">
           <param name="operationMode">RETRIEVE</param>
       </interceptor-ref>
       <interceptor-ref name="defaultStack" />
       <result>login.jsp</result>
   </action>
   

   But note that this would lead to infinite recursion due to the MessageStore Interceptor always adding errors and the Workflow Interceptor always returning "input"; to avoid it you should define a secondary defaultStack in your struts.xml with all the intercpetors except the Workflow one, otherwise the MessageStore with RETRIEVE will make it loop or, if you haven't defined an input result for your login action, complaining about a missing input result.

2. The second error is that you are redirecting, and hence losing the parameters. You're using the MessageStore Interceptor to preserve Action Messages, Action Errors and Field Errors across the redirection, but every other parameter is lost. If you want to preserve a parameter across a redirectAction you must explicitly send it, or store it in session in the source action and retrieving it in the destination action. In your case, it would be better to simply return the JSP in case of input result, instead of redirecting:

   <action name="authenticate" class="<Action_class_name>" method="<method_name>">
       <interceptor-ref name="store">
           <param name="operationMode">STORE</param>
       </interceptor-ref>
       <interceptor-ref name="defaultStack" />
       <result type="redirectAction">Successpage</result>
       <result name="input" >login.jsp</result>
   </action>
   <action name="login">
       <interceptor-ref name="defaultStack" />
       <result>login.jsp</result>
   </action>