How to do the value binding in datatable when selection mode = multiple - jsf

Question

I need explanation for the below value binding in the outputText inside p:dialog .I dont clear with that and is there any other way.
In my sample :
I have tried ,if i select the single or many check box the value get binded but when I click root check box which used for selecting all the check boxes, its getting selected but the values not get stored in the back end.
<p:dataTable id="checkboxDT"
var="car"
value="#{dtSelectionView.cars6}"
selection="#{dtSelectionView.selectedCars}"
rowKey="#{car.id}"
style="margin-bottom:0">
<f:facet name="header">
Checkbox
</f:facet>
<p:column selectionMode="multiple"
style="width:16px;text-align:center"/>
<p:column headerText="Id">
<h:outputText value="#{car.id}" />
</p:column>
<p:column headerText="Year">
<h:outputText value="#{car.year}" />
</p:column>
<p:column headerText="Brand">
<h:outputText value="#{car.brand}" />
</p:column>
<p:column headerText="Color">
<h:outputText value="#{car.color}" />
</p:column>
<f:facet name="footer">
<p:commandButton process="checkboxDT"
update=":form:multiCarDetail"
icon="ui-icon-search"
value="View"
oncomplete="PF('multiCarDialog').show()" />
</f:facet>
</p:dataTable>
<p:dialog header="Selected Cars"
widgetVar="multiCarDialog"
modal="true"
showEffect="fade"
hideEffect="fade"
resizable="false"
width="200">
<p:outputPanel id="multiCarDetail" style="text-align:center;">
<ui:repeat value="#{dtSelectionView.selectedCars}"
var="car">
<h:outputText value="#{car.id} - #{car.brand}"
style="display:block"/>
</ui:repeat>
</p:outputPanel>
</p:dialog>

Answer 1

You should update checkboxDT because update is used to determines id’s of components to be updated (refreshed with updated values from server). If you do not update checkboxDT, the selectedCars do not update too.
<p:commandButton process="checkboxDT"
update="checkboxDT,:form:multiCarDetail"
icon="ui-icon-search"
value="View"
oncomplete="PF('multiCarDialog').show()" />