Passing an action listener method as tagfile attribute

StackOverflow https://stackoverflow.com/questions/20242506

Question

I am creating a tagfile that contains a primefaces 3.5 dialog. the dialog contains a commandbutton and this button is parameterized with an actionlistener. The question is wether or not i can pass the actionlistener method as an attribute to the tagfile.

To clarify the quetsion I have prepared a testcase (using maven) with following dependencies

<dependency>
  <groupId>org.primefaces</groupId>
  <artifactId>primefaces</artifactId>
  <version>3.5</version>
</dependency>

<dependency>
  <groupId>com.sun.faces</groupId>
  <artifactId>jsf-api</artifactId>
  <version>2.2.4</version>
</dependency>

<dependency>
  <groupId>com.sun.faces</groupId>
  <artifactId>jsf-impl</artifactId>
  <version>2.2.4</version>
</dependency>

i define a taglib:

<?xml version="1.0" encoding="UTF-8"?>
<facelet-taglib version="2.0" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facelettaglibrary_2_0.xsd">
<namespace>http://demo.de/jsf/facelets</namespace>
<tag>
    <tag-name>DemoDialog</tag-name>
    <source>DemoDialog.xhtml</source>
</tag>  
</facelet-taglib>

and the DemoDialog.xhtml is like this:

<ui:composition 
   xmlns="http://www.w3.org/1999/xhtml"
   xmlns:h="http://java.sun.com/jsf/html"
   xmlns:ui="http://java.sun.com/jsf/facelets"
   xmlns:p="http://primefaces.org/ui"
   xmlns:c="http://java.sun.com/jsp/jstl/core">

  <c:if test="${empty dlgId}">
    <c:set var="dlgId" value="${id}" />
  </c:if>

  <c:if test="${empty widgetVar}">
    <c:set var="widgetVar" value="testDlg" />
  </c:if>

  ABC: #{okButtonActionListener}

  <p:dialog id="#{dlgId}" header="#{header}" widgetVar="#{widgetVar}">
    <h:form id="testForm" style="width: 400px;">
      <p:panelGrid>
        <p:row>
          <p:column>        
            <p:commandButton oncomplete="#{widgetVar}.hide()" value="Cancel" />
          </p:column>
          <p:column>
            <p:commandButton
               actionListener="${okButtonActionListener}"
               oncomplete="#{widgetVar}.hide()"
               value="Ok" />
          </p:column>
        </p:row>
      </p:panelGrid>
    </h:form>
  </p:dialog>
</ui:composition>

finally the DemoDialog tag is in use in a sample xhtml page

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:h="http://java.sun.com/jsf/html"
      xmlns:f="http://java.sun.com/jsf/core"
      xmlns:ui="http://java.sun.com/jsf/facelets"
      xmlns:p="http://primefaces.org/ui"
      xmlns:li="http://demo.de/jsf/facelets">
  <f:view contentType="text/html">
    <h:head>
      <f:facet name="first">
        <meta http-equiv="X-UA-Compatible" content="EmulateIE8" />
        <meta content='text/html; charset=UTF-8' http-equiv="Content-Type"/>
        <title>Dialog Template test</title>
      </f:facet>
    </h:head>
    <h:body>
      <h:form id="demoForm">
      <p:commandButton onclick="testDlg.show()"/>
      </h:form>
      <li:DemoDialog id="lidemo" onclick="alert('hello')" okButtonActionListener="\${dialogBean.action_listener()}">
      </li:DemoDialog>
    </h:body>
  </f:view>
</html>

To test the page I start jetty via maven (mvn jetty:run-war).

Was it helpful?

Solution

You need to declare the tag attribute as a method expression attribute in the .taglib.xml by explicitly declaring a <method-signature>. It indeed defaults to a value expression.

<tag>
    <tag-name>DemoDialog</tag-name>
    <source>DemoDialog.xhtml</source>
    <attribute>
        <name>okButtonActionListener</name>
        <method-signature>void actionListener(javax.faces.event.ActionEvent)</method-signature>
    </attribute>
</tag>

(the method name actionListener is fully free to your choice; what counts are the return type and parameter types, those have to be fully qualified names)

Additional bonus, explicitly declaring tag attribtues in .taglib.xml enables IDE autocompletion on those.

Licensed under: CC-BY-SA with attribution
Not affiliated with StackOverflow
scroll top