jsf 2 - JSF lazy loading component value

Question

Consider a simple h:outputText component:

<h:outputText value="#{myBean.myValue}"/>

How can I lazy load that value after the page has been rendered, and display custom 'ajax loading' icon instead of the value while this is being done?

I am using PrimeFaces 3.5 in my project so any PF-specific implementation will be welcome.

Answer 1

A suggest to do this by calling remoteCommand after on page load (it is done by setting autoRun attribute to true) and update your outputText.

private String myValue;

// getter and setter

public void initMyValue() {
  // init myValue
}

On page you should have ajaxStatus component for viewing loading image, and your outputText. Also there should be p:remoteCommand component:

<p:ajaxStatus style="width:16px;height:16px;" id="ajaxStatusPanel">  
  <f:facet name="start">  
    <h:graphicImage value="ajaxloading.gif" />  
  </f:facet>
  <f:facet name="complete">  
    <h:outputText value="" />
  </f:facet>  
</p:ajaxStatus>

<h:outputText id="myText" value="#{myBean.myValue}"/>

<p:remoteCommand autoRun="true" actionListener="#{myBean.initMyValue}" update="myText"/>

EDIT: I supposed that you want to lazy load value of outputText because it contains some long running calculations, but if you want to completely deffer rendering of outputText first add boolean property in your backing bean, and set this property to true at the end of initMyValue method:

private boolean loaded;

// getter and setter

public void initMyValue() {
  // init myValue
  loaded = true;
}

on the page reorganize it as follows:

<h:panelGroup id="myPanel" layout="block">
  <h:graphicImage value="ajaxloading.gif" rendered="#{!myBean.loaded}"/>
  <h:outputText value="#{myBean.myValue}" rendered="#{myBean.loaded}"/>
</h:panelGroup>

<p:remoteCommand autoRun="true" actionListener="#{myBean.initMyValue}" update="myPanel"/>