A requirement on OTN was to disable the dependent
list box of a model driven
list of value configuration whenever the
list is empty. To disable the dependent
list, the af:selectOneChoice component needs to be refreshed with every value change of the parent
list, which however already is the case as the
list boxes are already dependent. When you create model driven
list of values as choice lists in an ADF Faces page, two ADF
list bindings are implicitly created in the PageDef
file of the page that hosts the input form. At runtime, a
list binding is an instance of FacesCtrlListBinding, which exposes getItems() as a method to access a
list of available child data (java.util.List). Using Expression Language, the
list is accessible with #{bindings.list_attribute_name.items} To dynamically set the disabled property on the dependent af:selectOneChoice component, however, you need a managed bean that exposes the following two methods //empty – but required – setter method public void setIsEmpty(boolean isEmpty) {} //the method that returns true/false when the
list is empty or //has values public boolean isIsEmpty() { FacesContext fctx = FacesContext.getCurrentInstance(); ELContext elctx = fctx.getELContext(); ExpressionFactory exprFactory = fctx.getApplication().getExpressionFactory(); ValueExpression vexpr = exprFactory.createValueExpression(elctx, "#{bindings.EmployeeId.items}", Object.class);
List employeesList = (List) vexpr.getValue(elctx); return employeesList.isEmpty()? true : false; } If referenced from the dependent choice
list, as shown below, the
list is disabled whenever it contains no
list data <! -- master
list --> <af:selectOneChoice value="#{bindings.DepartmentId.inputValue}" label="#{bindings.DepartmentId.label}" required="#{bindings.DepartmentId.hints.mandatory}" shortDesc="#{bindings.DepartmentId.hints.tooltip}" id="soc1" autoSubmit="true"> <f:selectItems value="#{bindings.DepartmentId.items}" id="si1"/> </af:selectOneChoice> <! -- dependent
list --> <af:selectOneChoice value="#{bindings.EmployeeId.inputValue}" label="#{bindings.EmployeeId.label}" required="#{bindings.EmployeeId.hints.mandatory}" shortDesc="#{bindings.EmployeeId.hints.tooltip}" id="soc2" disabled="#{lovTestbean.isEmpty}" partialTriggers="soc1"> <f:selectItems value="#{bindings.EmployeeId.items}" id="si2"/> </af:selectOneChoice>
