I have a page with a very simple form which submits ajax requests targeted only at components in that same form. In the same page (but outside the form), there is also a ui:repeat which iterates over an array returned from a request scoped managed bean (suppose a list of product categories). This bean has no properties bound in the form and is not accessed in any other way apart from the value attribute of the ui:repeat tag. I don't understand why JSF needs to recreate the request scoped bean on every ajax postback, just as if I asked to render this external ui:repeat (which has nothing to do with the form) along with some component inside the form.
Is it a bug? Or is it an expected behavior? Of course I could annotate the bean as ViewScoped but I don't see the reason to have categories stored in the view scope as they are completely static between postbacks.
Another solution/workaround I found is to render the ui:repeat only in case of non-ajax requests:
<ul>
<ui:repeat value="#{someRequestScopedBean.categories}" var="category" rendered="#{not facesContext.partialViewContext.ajaxRequest}">
<li>#{category.name}</li>
</ui:repeat>
</ul>
but I don't know if this could cause problems and looks not very clear.
TEST CASE
index.xhtml:
<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
xmlns:f="http://xmlns.jcp.org/jsf/core">
<h:head>
<title>Facelet Title</title>
</h:head>
<h:body>
<h1>Test page</h1>
<p>Random jokes</p>
<ul>
<ui:repeat value="#{oneLiners.list}" var="oneliner">
<li>#{oneliner}</li>
</ui:repeat>
</ul>
<h:form>
<h:selectOneMenu value="#{backingBean.greeting}" hideNoSelectionOption="true">
<f:selectItem value="#{null}" itemLabel="Select a greeting..." noSelectionOption="true"/>
<f:selectItems value="#{backingBean.greetings}"/>
<f:ajax render="@this btn"/>
</h:selectOneMenu>
<h:commandButton id="btn" value="Say Hello!" disabled="#{empty backingBean.greeting}">
<f:ajax render="otxt"/>
</h:commandButton>
<h:outputText id="otxt" value="#{backingBean.greeting}, Maurizio!" style="display: #{empty backingBean.greeting ? 'none' : 'block'}"/>
</h:form>
</h:body>
</html>
Request scoped bean:
package testuirepajax;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
/**
*
* @author maurizio
*/
@ManagedBean
@RequestScoped
public class OneLiners {
private String[] list;
public OneLiners() {
System.out.println("testuirepajax.OneLiners.<init>()");
list = new String[] {
"Life is wonderful. Without it we'd all be dead.",
"Daddy, why doesn't this magnet pick up this floppy disk?",
"Daddy, what does FORMATTING DRIVE C mean?",
"Never forget: 2 + 2 = 5 for extremely large values of 2.",
"C:\\ is the root of all directories."
};
}
public String[] getList() {
System.out.println("testuirepajax.OneLiners.getList()");
return list;
}
}
Form backing bean:
package testuirepajax;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ViewScoped;
/**
*
* @author maurizio
*/
@ManagedBean
@ViewScoped
public class BackingBean {
private String[] greetings;
private String greeting;
public BackingBean() {
System.out.println("testuirepajax.BackingBean.<init>()");
greetings = new String[] {
"Hello", "Hi", "Good morning", "Good evening", "Good night"
};
}
public String[] getGreetings() {
return greetings;
}
public void setGreeting(String greeting) {
this.greeting = greeting;
}
public String getGreeting() {
return greeting;
}
}
Check the output of your container. Using the Payara Server (which ships Mojarra 2.2.12), I see lines like these:
Informazioni: testuirepajax.OneLiners.<init>()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.<init>()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
Informazioni: testuirepajax.OneLiners.getList()
when selecting elements from the menu or clicking the "Say Hello!" button.
