Af:tree selected item

Question

I want to display the selected item from a tree (and to store this into a variable). I tried with selection_listener, but I don't know exactly what to write in the bean. The disclosed_row_keys is used to expand all nodes.
<af:tree value="#{bindings.ConfigTreeParent2.treeModel}"
var="node"
rowSelection="single" id="tree1"
selectionListener="#{left_tree.selection_listener}"
disclosedRowKeys="#{left_tree.disclosed_row_keys}">
<f:facet name="nodeStamp">
<af:outputText value="#{node}"/>
</f:facet>
</af:tree>
Thanks,
vio

Answer 1

Hi vio,
The method signature for selectionListener is
public void someMethodName(SelectionEvent ev);
The selection event contains the selected row keys (well actually it contains the delta which should be improved imho like oldSelection and newSelection, but in the case of single selection, you can simply use the added list more or less), you can then extract the data associated with each row keys. So, in your case, I suggest you inject the TreeModel in your bean. Here's an example:
In the code:
public class MyTreeController
    private TreeModel model;
    private MySelectionManager selectionManager;
    public TreeModel getTreeModel()
        return model;
    public void setTreeModel(TreeModel model)
        this.model = model;
    public MySelectionManager getSelectionManager()
        return selectionManager;
    public void setSelectionManager(MySelectionManager manager)
        this.selectionManager = manager;
    public void selectionPerformed(SelectionEvent ev)
        Object selected = getFirstRowKey(ev.getAddedSet());
        if (selected == null)
            Object unselected = getFirstRowKey(ev.getRemovedSet());
            if (selectionManager.isSelected(getRowData(unselected)))
                selectionManager.setSelection(null);
        else
            selectionManager.setSelection(getRowData(selected));
    private Object getFirstRowKey(RowKeySet set)
        for (Object key : set)
            return key;
        return null;
    private Object getRowData(Object rowKey)
        TreeModel model = getTreeModel();
        Object oldRowKey = model.getRowKey();
        try
            model.setRowKey(rowKey);
            return model.getRowData();
        finally
            model.setRowKey(oldRowKey); // Always restore the state
public class MySelectionManager
    private Object selection; // Or another more precise type
    public Object getSelection()
        return selection;
    public boolean isSelected(Object data)
        return selection != null && selection.equals(data);
    public void setSelection(Object selection)
        this.selection = selection;
}In the faces-config.xml
<managed-bean>
  <managed-bean-name>selectionManager</managed-bean-name>
  <managed-bean-class>MySelectionManager</managed-bean-class>
  <managed-bean-scope>pageFlow</managed-bean-scope> <!-- That one can be persistent across requests -->
</managed-bean>
<managed-bean>
  <managed-bean-name>treeController</managed-bean-name>
  <managed-bean-class>MyTreeController</managed-bean-class>
  <managed-bean-scope>request</managed-bean-scope>
<!-- request scope is important here since we don't know the exact lifespan of bindings.ConfigTreeParent2.treeModel -->
  <managed-property>
    <property-name>selectionManager</property-name>
    <property-class>MySelectionManager</property-class>
    <value>#{selectionManager}</value>
  </managed-property>
  <managed-property>
    <property-name>treeModel</property-name>
    <property-class>org.apache.myfaces.trinidad.model.TreeModel</property-class>
    <value>#{bindings.ConfigTreeParent2.treeModel}</value>
  </managed-property>
</managed-bean>In your page:
<af:tree value="#{treeController.treeModel}"
         var="node"
         id="tree1"
         rowSelection="single"
         selectionListener="#{treeController.selectionPerformed}"
         disclosedRowKeys="#{left_tree.disclosed_row_keys}">
  <f:facet name="nodeStamp">
    <af:outputText value="#{node}"/>
  </f:facet>
</af:tree>Note that I preferred to use the tree model from the bean rather than using directly the databindings here. I did so to improve reusability and declarativity of the page as you could now simply alter the injected tree model within the faces-config to have your page point on a completely different data source.
Regards,
~ Simon