Application of af:setPropertyListener

The af:setPropertyListener comes very handy when we use af:iterator and need some processing to be done on an event fired by a component within the iterator.

af:iterator dynamically creates the multiple component instances of the component defined within in during design time. If we want to do some processing on event handling of a component instance within that, af:setPropertyListener is very useful.

Consider a scenario where we have a list of booleans to be rendered in a UI page. We can use af:iterator as below:

<af:panelGroupLayout id="pgl8" layout="vertical">
<af:iterator id="i1" value="#{pageFlowScope.accessGroups}"
                                 var="accessGroup">
                  <af:selectBooleanCheckbox text="#{accessGroup.name}"
                                                                value="#{accessGroup.selected}"
                                                                label=""
                                                                id="sbc1" autoSubmit="true"
                                                                disabled="#{ !accessGroup.canModify}"
                                                                rendered="#{accessGroup ne null}"
                                    valueChangeListener="#{myBean.onSelectionChangeOfAccessGroup}">
                        
                            <af:setPropertyListener from="#{accessGroup.name}"
                                                                to="#{requestScope.selChangedAccessGroupName}"
                                                                type="valueChange"/>
                  </af:selectBooleanCheckbox>
</af:panelGroupLayout>

In the above example, the iterator iterates over the collection of booleans accessGroups. As per the layout in which it is contained, we get n checkboxes vertically aligned for n entries in the collection.

If the user wants to change a particular checkbox selection and do some processing on the value change of that checkbox by depending on the instance of accessGroup's other attributes, it is definitely necessary to have a reference of that accessGroup instance which is impossible to to know during the design time. Hence I used setPropertyListener to capture the accessGroup instance into a requestScope variable "selChangedAccessGroupName". I will use this in my event handling logic to do some processing as per the requirement. Sample code shown below.


myBean.java:

public class myBean implements Serializable{
        
             public void onSelectionChangeOfAccessGroup(valueChangeEvent e){
                    AccessGroup ag = ADFContext.getCurrent().getRequestScope().get("selChangedAccessGroupName")

                if(e.getNewValue){
                   // Invoke business service method by passing ag.getName() and e.getNewValue
                }

            }
}

The setPropertyListener from attribute is configured with value to be read and to attribute captures it into a requestScope variable. The type attribute is configured with event when the value need to be captured. This type attribute can be changed to different event types based on the requirement.