Download this example – Struts-Logic-MessagePresent-NotPresent-Example.zip

Struts <logic:messagesPresent> tag is used to check the given message or error message exists on the current request.

  • “Messages” are ActionMessages , under the key Globals.MESSAGE_KEY in the current request.
  • “Error Messages” are ActionErrors , under the key Globals.ERROR_KEY in the current request.

Here’s few examples to show the use of the <logic:messagesPresent> and <logic:messagesNotPresent>.

  1. If there is any error messages or messages exists under key “Globals.ERROR_KEY” or “Globals.MESSAGE_KEY”, the body of the tag will be execute.
    <logic:messagesPresent>
	There are errors on this page!
</logic:messagesPresent>
<logic:messagesNotPresent>
	There are no errors on this page!
</logic:messagesNotPresent>
  2. If there is any error messages or messages named “common.email.err” exists under key “Globals.ERROR_KEY”, the body of the tag will be execute.
    <logic:messagesPresent property="common.email.err">
	Email address has error messages! Globals.ERROR_KEY
</logic:messagesPresent>
<logic:messagesNotPresent property="common.email.err">
	Email address has no error messages! - Globals.ERROR_KEY
</logic:messagesNotPresent>
  3. If there is any error messages or messages named “common.email.err” exists under key “Globals.MESSAGE_KEY”, the body of the tag will be execute.
    <logic:messagesPresent property="common.email.err" message="true">
	Email address has error messages! - Globals.MESSAGE_KEY
</logic:messagesPresent>
<logic:messagesNotPresent property="common.email.err" message="true">
	Email address has no error messages! - Globals.MESSAGE_KEY
</logic:messagesNotPresent>

LogicExampleAction.java

package com.mkyong.common.action;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
 
public class LogicExampleAction extends Action{
 
	public ActionForward execute(ActionMapping mapping,ActionForm form,
		HttpServletRequest request,HttpServletResponse response) 
        throws Exception {
 
		//do nothing
 
	    return mapping.findForward("success");
	}
 
}

EmailForm.java – ActionForm to return an error message – ActionErrors.

package com.mkyong.common.form;
 
import javax.servlet.http.HttpServletRequest;
 
import org.apache.struts.action.ActionErrors;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionMessage;
 
public class EmailForm extends ActionForm{
 
	String email; 
 
	public String getEmail() {
		return email;
	}
 
	public void setEmail(String email) {
		this.email = email;
	}
 
	@Override
	public ActionErrors validate(ActionMapping mapping,
	HttpServletRequest request) {
 
	   ActionErrors errors = new ActionErrors();
 
	   errors.add("common.email.err",
		new ActionMessage("error.common.email.required"));
 
	   return errors;
 
	}
}

Common.properties

#common module error message
error.common.email.required = Email is required.

LogicExample.jsp

<%@taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>
<%@taglib uri="http://struts.apache.org/tags-logic" prefix="logic"%>
<html>
<head>
</head>
<body>
 
<h2>Struts - &lt;logic:messagesPresent&gt; & &lt;logic:messagesNotPresent&gt;</h2>
 
<logic:messagesPresent>
	There are errors on this page!
</logic:messagesPresent>
<logic:messagesNotPresent>
	There are no errors on this page!
</logic:messagesNotPresent>
 
<br/><br/>
 
<logic:messagesPresent property="common.email.err">
	Email address has error messages! Globals.ERROR_KEY
</logic:messagesPresent>
<logic:messagesNotPresent property="common.email.err">
	Email address has no error messages! - Globals.ERROR_KEY
</logic:messagesNotPresent>
 
<br/><br/>
 
<logic:messagesPresent property="common.email.err" message="true">
	Email address has error messages! - Globals.MESSAGE_KEY
</logic:messagesPresent>
<logic:messagesNotPresent property="common.email.err" message="true">
	Email address has no error messages! - Globals.MESSAGE_KEY
</logic:messagesNotPresent>
 
<br/><br/>
 
</body>
</html>

struts-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC 
"-//Apache Software Foundation//DTD Struts Configuration 1.3//EN" 
"http://jakarta.apache.org/struts/dtds/struts-config_1_3.dtd">
 
<struts-config>
 
	<form-beans>
 
		<form-bean name="emailForm" 
			type="com.mkyong.common.form.EmailForm"></form-bean>
 
	</form-beans>
 
	<action-mappings>
 
	 	<action
			path="/LogicTest"
			type="com.mkyong.common.action.LogicExampleAction"
			name="emailForm"
			validate="true"
			input="/pages/LogicExample.jsp"
			>
 
			<forward name="success" path="/pages/LogicExample.jsp"/>
 
		</action>
 
	</action-mappings>
 
	<message-resources
		parameter="com.mkyong.common.Common" />
 
 
</struts-config>

Result

http://localhost:8080/StrutsExample/LogicTest.do

Struts-logic-messages-present-notpresent-example
Struts - <logic:messagesPresent> & <logic:messagesNotPresent>
There are errors on this page!
 
Email address has error messages! Globals.ERROR_KEY
 
Email address has no error messages! - Globals.MESSAGE_KEY
Any Java questions or problems? please post at this JavaNullPointer.com forum, see you there ~
[ Read More ] You can find more similar articles at Struts 1.x Tutorials