Defaulting selectonechoice dropdown that is a component of an af:treetable

<af:form id="f1">

      <af:panelGridLayout id="pgl1">

        <af:gridRow height="100%" id="gr1">

          <af:gridCell width="100%" halign="center" valign="middle" id="gc1">

            <af:selectOneChoice value="#{bindings.DepartmentsView1_1.inputValue}"

                      label="#{bindings.DepartmentsView1_1.label}" autoSubmit="true"

                      immediate="true"

                      required="#{bindings.DepartmentsView1_1.hints.mandatory}"

                      shortDesc="#{bindings.DepartmentsView1_1.hints.tooltip}" id="soc1">

              <f:selectItems value="#{bindings.DepartmentsView1_1.items}" id="si1"/>

              <f:validator binding="#{bindings.DepartmentsView1_1.validator}"/>

            </af:selectOneChoice>

            <af:button text="Employees" id="b1">

              <af:showPopupBehavior popupId="p1"/>

            </af:button>

          </af:gridCell>

        </af:gridRow>

      </af:panelGridLayout>

      <af:popup childCreation="deferred" autoCancel="disabled" id="p1" contentDelivery="lazyUncached"

           binding="#{backingBeanScope.TestBean.testPopup}">

        <af:dialog id="d2">

          <f:facet name="buttonBar"/>

          <af:treeTable value="#{bindings.EmployeesView1_3.treeModel}" var="node" partialTriggers="::soc1"

                 rowSelection="single" id="tt1">

            <f:facet name="nodeStamp">

              <af:column id="c1" width="100" headerText="Empployee Id">

                <af:outputText value="#{node.bindings.EmployeeId.inputValue}" id="ot1"/>

              </af:column>

            </f:facet>

            <af:column id="c2" width="200" headerText="First Name">

              <af:outputText value="#{node.bindings.FirstName.inputValue}" id="ot2"/>

            </af:column>

            <af:column id="c3" width="200" headerText="LastName">

              <af:outputText value="#{node.bindings.LastName.inputValue}" id="ot3"/>

            </af:column>

            <af:column id="c4" width="100" headerText="Salary">

              <af:outputText value="#{node.bindings.Salary.inputValue}" id="ot4"/>

            </af:column>

            <af:column id="c5" width="100" headerText="Job History IDs">

              <af:selectOneChoice value="#{node.bindings.JobId.inputValue}" label="#{node.bindings.JobId.label}" 

                        shortDesc="#{node.bindings.JobId.hints.tooltip}" id="soc2">

                <f:selectItems value="#{node.bindings.JobId.items}" id="si2"/>

              </af:selectOneChoice>

            </af:column>

            <f:facet name="pathStamp">

              <af:outputText value="#{node}" id="ot998"/>

            </f:facet>

          </af:treeTable>

        </af:dialog>

      </af:popup>

    </af:form>

Here are some screenshots that may help explain.

In the example, you select a department from the dropdown, and then the employees button opens a popup containing a list of employee data on a treetable for that department.

Under Employee ID 101, there are job history IDs in SOC dropdowns shown in child rows. Both children have two choices in their SOCs, and so should default to no selection or null.

Under Employee Id 102 , there is one child with job history SOC of IT_PROG. This SOC only has one choice in the dropdown, and in this case I would want it to default to IT_PROG.