p:ajax not updating p:inputText - jsf

Question

I am unable to update a <p:inputText> based on the value entered in another <p:inputText> using <p:ajax>. I am using JSF 2 with PrimeFaces 5. The second <p:inputText> is not updating, the listener associated with <p:ajax> is being called and i am getting the correct values in the listener but its not updated on the view.
the view code is:
<p:dialog id="newStdDlg" header="Add new Student" widgetVar="newStdDlg" modal="true">
<h:panelGrid id="newStdDlgPanel" columns="2" cellpadding="5" style="width:100%;">
<p:outputLabel value="First Name *" />
<p:inputText id="studentfname" value="#{addStudentBean.student.firstName}">
<p:ajax event="change" update="studentUsrname" listener="#{addStudentBean.firstNameChange}" />
</p:inputText>
<p:outputLabel value="Last Name *" />
<p:inputText value="#{addStudentBean.student.lastName}"/>
<p:outputLabel value="Father's Name *" />
<p:inputText value="#{addStudentBean.student.fatherName}"/>
<p:outputLabel id="uLbl" value="Username (System Generated) *" />
<p:inputText id="studentUsrname" value="#{addStudentBean.student.user.username}" />
<p:outputLabel value="This temporary password would be mailed to user: " />
<p:outputLabel id="stdpassword" value="#{addStudentBean.student.user.password}"/>
</h:panelGrid>
<p:commandButton value="Create Student"
actionListener="#{addStudentBean.addNewStudentAction}"
style="margin-left:auto;margin-right:auto;display:block;"/>
</p:dialog>
and the listener of the session scoped managed bean is :
public void firstNameChange() {
System.out.println("In AddStudentBean().firstNameChange()..........");
System.out.println("The value of student.getFirstName: "+student.getFirstName());
System.out.println("updating system generated username as: "+student.getFirstName()+String.valueOf(new UserDAO().getUserCount()+1));
student.getUser().setUsername(student.getFirstName()+String.valueOf(new UserDAO().getUserCount()+1));
student.getUser().setPassword(KaaloUtils.getPassword());
}

Answer 1

Like Jaqen mentioned in comments the comments use h:form inside dialog.
If you want to update the component from ManagedBean you can do that by using org.primefaces.RequestContext's update method.
RequestContext.getCurrentInstance().update("COMPONENT_ID_TO_UPDATE")
If you feel like this method is too Cohesive, you can update from Facelet only, make sure remember to not place p:dialog in a h:from instead use h:form inside p:dialog .