DataTable: Cannot update footer only as initial footer is not rendered anymore

1) Environment

• PrimeFaces version: 7.0
• Application server + version: Tomcat 8.5.37
• Affected browsers: tested with Firefox and Edge

2) Expected behavior

<h:panelGroup id="buttonPanel"> component in <f:facet name="footer"> should be updateable (without updating the whole datatable) even if in the initial state all <p:commandButton> components are not rendered.

3) Actual behavior

I need to update the whole datatable to have an updated footer with buttons based on the selected row.

4) Steps to reproduce

Extend showcase Single with Row Click (https://www.primefaces.org/showcase/ui/data/datatable/selection.xhtml) by showing the button only if a row is selected. We therefore currently add a named container, e.g. h:panelGroup which can be separately updated and accordingly add row select and unselect events.

5) Sample XHTML

<p:dataTable id="singleDT" var="car" value="#{dtSelectionView.cars2}" selectionMode="single" selection="#{dtSelectionView.selectedCar}" rowKey="#{car.id}">
    <f:facet name="header">
        Single with Row Click
    </f:facet>
    <p:ajax event="rowSelect" update="buttonPanel" />
    <p:ajax event="rowUnselect" update="buttonPanel" />
    <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">
        <h:panelGroup id="buttonPanel">
            <p:commandButton process="singleDT" update=":form:carDetail" icon="pi pi-search" value="View" oncomplete="PF('carDialog').show()" rendered="#{dtSelectionView.selectedCar != null}" />
        </h:panelGroup>
    </f:facet>
</p:dataTable>

6) Sample bean

unchanged to showcase.

This is probably caused by https://github.com/primefaces/primefaces/issues/2825. Our current solution still worked with PrimeFaces 6.1.

[tandraschko]

i think the easiest way would be to add a attribute showEmptyFooter, which defaults to false?

[jansohn]

I’m also for an attribute to switch between the two options.