primefaces dont validate ajax rendered component - ajax

Question

<h:form id="formEdit">
<p:selectOneMenu value="#{testView.selection}"
required="true">
<f:selectItem itemValue="noMenu" itemLabel="selectOneMenu not rendered"/>
<f:selectItem itemValue="haveMenu" itemLabel="selectOneMenu rendered"/>
<p:ajax update="formEdit"/>
</p:selectOneMenu>
<p:panel>
<p:selectOneMenu id="conditionallyRnedered" value="#{testView.value}"
rendered="#{testView.selection eq 'haveMenu'}"
required="true">
<f:selectItem itemValue="#{null}" itemLabel="-" noSelectionOption="true"/>
</p:selectOneMenu>
</p:panel>
<p:messages id="messages"/>
<p:commandButton value="Submit"/>
</h:form>
Component "conditionallyRnedered" is required, and rendered on page after i select "haveMenu" value in first menu. This component have only empty option and initialy its not rendered on page. If i press Submit button, then response is:
<partial-response><changes>
<update id="javax.faces.ViewState"><![CDATA[stateless]]></update>
</changes></partial-response>
There is no validation error. If i change value of rendered attribute in "conditionallyRnedered" from "#{testView.selection eq 'haveMenu'}" to just "true", then response is:
<partial-response><changes>
<update id="javax.faces.ViewState"><![CDATA[stateless]]></update>
<extension ln="primefaces" type="args">{"validationFailed":true}</extension></changes>
</partial-response>
Validation error returned. The questions is:
Why conditionally rendered component is not validated?
It is possible to make them validated?
UPD
Originally in my question is absent Bean source code, in which Bean declared as #ViewScoped. After read #BalusC comment, i try to change scope from #ViewScoped to #SessionScoped, and after that validation is working correctly. Wherein javax.faces.ViewState in response changed from stateless to some view id:
<update id="javax.faces.ViewState">-5902669082498843838:729675320168079573</update>
I still doubt, this is solution or still workaround, because I thought that instance of #ViewScoped bean is exist while we dont left the page. Maybe this behavior is caused by the fact that in the same page present another bean, with #SessionScoped scope.

Answer 1

It failed for the technical reason explained in this Q&A: Form submit in conditionally rendered component is not processed. In a nutshell, JSF will re-check the rendered attribute during processing the form submit/conversion/validation and skip components which aren't rendered during that moment. The answer is to use a #ViewScoped bean.
That it still failed in spite of that you're actually using a #ViewScoped bean is because you're using a stateless view via <f:view transient="true">, as confirmed by the actual javax.faces.ViewState value and What is the usefulness of statelessness in JSF? In other words, JSF won't save/restore the view, including any view scoped beans. Those beans will technically behave like #RequestScoped beans and thus be recreated on every request, resetting their properties to defaults everytime.
To solve your problem, just turn off stateless view by removing <f:view transient="true"> and keep your bean #ViewScoped.

Answer 2

#bobzer,
primefaces commandButton has become ajax="true" by default. So when i set ajax="false", the form is submitted and i can see validation errors
i get
My xhtml:
<h:form id="formEdit">
<p:selectOneMenu value="#{testView.selection}" required="true">
<f:selectItem itemValue="noMenu"
itemLabel="selectOneMenu not rendered" />
<f:selectItem itemValue="haveMenu" itemLabel="selectOneMenu rendered" />
<p:ajax update="formEdit" />
</p:selectOneMenu>
<p:panel>
<p:selectOneMenu id="conditionallyRnedered" value="#{testView.value}"
rendered="#{testView.selection eq 'haveMenu'}" required="true">
<f:selectItem itemValue="#{null}" itemLabel="-"
noSelectionOption="true" />
</p:selectOneMenu>
</p:panel>
<p:messages id="messages" />
<p:commandButton value="Submit" ajax="false"/>
</h:form>
My Bean
package citi.manageID.framework.admin.roleMgmt;
import javax.faces.view.ViewScoped;
import javax.inject.Named;
#Named
#ViewScoped
public class TestView {
private String selection="";
private String value="";
public String getSelection() {
return selection;
}
public void setSelection(String selection) {
this.selection = selection;
}
public String getValue() {
return value;
}
public void setValue(String value) {
this.value = value;
}
}