PrimeFaces commandButton ajax does not work - ajax

Question

I have simple JSF page and simple backing bean. I have p:commandButton on the page and p:datatable. With commandButton I need to update dataTable with ajax, but it does not happens. What could be the reason?
Here is the page:
<ui:define name="content">
<h2>#{menu['management.roles.perms']}</h2>
<h:form id="form">
<p:fieldset style="border: 0px" toggleable="false" collapsed="false">
<p:tabView>
<p:tab title="#{messages['roles']}">
<p:dataTable id="dataTable" value="#{rolesBean.roles}" var="role"
editable="true" rows="10" rowKey="#{role.id}">
<p:ajax event="rowEdit" listener="#{rolesBean.onEdit}"/>
<f:facet name="footer">
<p:commandButton value="#{misc['add.role']}"
actionListener="#{rolesBean.addRole}" update="dataTable"/>
</f:facet>
<p:column headerText="#{misc['name.database']}">
<p:cellEditor>
<f:facet name="output">
<h:outputText value="#{role.name}"/>
</f:facet>
<f:facet name="input">
<h:inputText value="#{role.name}"/>
</f:facet>
</p:cellEditor>
</p:column>
<p:column headerText="#{misc['date']}">
<f:facet name="output">
<h:outputText value="#{role.creationDate}">
<f:convertDateTime pattern="dd.MM.yyyy" />
</h:outputText>
</f:facet>
</p:column>
<p:column headerText="#{misc['description']}">
<p:cellEditor>
<f:facet name="output">
<h:outputText value="#{role.description}"/>
</f:facet>
<f:facet name="input">
<h:inputText value="#{role.description}"/>
</f:facet>
</p:cellEditor>
</p:column>
<p:column headerText="#{messages['edit']}">
<p:rowEditor />
</p:column>
</p:dataTable>
</p:tab>
<p:tab title="#{messages['perms']}">
</p:tab>
<p:tab title="#{clients['history']}">
</p:tab>
</p:tabView>
</p:fieldset>
</h:form>
</ui:define>
And here is the code of backingBean:
#ViewScoped
#ManagedBean(name = "rolesBean")
public class RolesViewBean extends BasicViewBean<Role> {
private static final long serialVersionUID = 27377603187254821L;
#Inject
RoleDao dao;
private List<Role> roles;
#Override
protected BasicDao<Role> getDAO() {
return dao;
}
public void onEdit(RowEditEvent event){
this.entity = (Role) event.getObject();
dao.update(this.entity);
}
public void addRole(){
roles.add(new Role());
}
public List<Role> getRoles() {
roles = dao.getRoleList();
return roles;
}
public void setRoles(List<Role> roles) {
this.roles = roles;
}
}

Answer 1

At first glance, the problem is that your addRole method modifes the "roles" list, while the getRoles (which gets called by the dataTable) resets it to whatever is saved in the database.
So your datatabe gets updated, it' just that it gets updated with the same values.
Think about that ;)