Drag and Drop feature of Rich Tree
Hi Friends,
I am using Seam for developing my application. In one scenario i need to use rich:tree component with drag and drop behavior.
But i am getting problem with droplistener method. As it is giving the null pointer exception. Could you please send me some demo of how to implement this feature into my application.
Following is the code used by me for this
public void dropListener(DropEvent dropEvent) {
// resolve drag destination attributes
UITreeNode destNode = (dropEvent.getSource() instanceof UITreeNode) ? (UITreeNode) dropEvent.getSource() : null;
UITree destTree = destNode != null ? destNode.getUITree() : null;
TreeRowKey dropNodeKey = (dropEvent.getDropValue() instanceof TreeRowKey) ? (TreeRowKey) dropEvent.getDropValue() : null;
TreeNode droppedInNode = dropNodeKey != null ? destTree.getTreeNode(dropNodeKey) : null;
// resolve drag source attributes
UITreeNode srcNode = (dropEvent.getDraggableSource() instanceof UITreeNode) ? (UITreeNode) dropEvent.getDraggableSource() : null;
UITree srcTree = srcNode != null ? srcNode.getUITree() : null;
TreeRowKey dragNodeKey = (dropEvent.getDragValue() instanceof TreeRowKey) ? (TreeRowKey) dropEvent.getDragValue() : null;
TreeNode draggedNode = dragNodeKey != null ? srcTree.getTreeNode(dragNodeKey) : null;
if (dropEvent.getDraggableSource() instanceof UIDragSupport && srcTree == null && draggedNode == null && dropEvent.getDragValue() instanceof TreeNode) {
srcTree = destTree;
draggedNode = (TreeNode) dropEvent.getDragValue();
dragNodeKey = srcTree.getTreeNodeRowKey(draggedNode) instanceof TreeRowKey ? (TreeRowKey) srcTree.getTreeNodeRowKey(draggedNode) : null;
}
// Note: check if we dropped node on to itself or to item instead of
// folder here
if (droppedInNode != null && (droppedInNode.equals(draggedNode) || droppedInNode.getParent().getParent() != null || draggedNode.getParent().getParent() == null)) {
System.out.println("Warning: Can't drop on itself or to pic itself! Also can't move folders");
return;
}
FacesContext context = FacesContext.getCurrentInstance();
if (dropNodeKey != null) {
// add destination node for rerender
destTree.addRequestKey(dropNodeKey);
Object state = null;
if (dragNodeKey != null) { // Drag from this or other tree
TreeNode parentNode = draggedNode.getParent();
// 1. remove node from tree
state = srcTree.removeNode(dragNodeKey);
// 2. add parent for rerender
Object rowKey = srcTree.getTreeNodeRowKey(parentNode);
srcTree.addRequestKey(rowKey);
if (dropEvent.getDraggableSource() instanceof UIDragSupport) {
selectedNodeChildren.remove(draggedNode);
// if node was gragged in it's parent place dragged node to
// the end of selected nodes in grid
if (droppedInNode.equals(parentNode)) {
selectedNodeChildren.add(draggedNode);
}
}
} else if (dropEvent.getDragValue() != null) { // Drag from some
// drag source
draggedNode = new DemoTreeNodeImpl<String>();
draggedNode.setData(dropEvent.getDragValue().toString());
}
// generate new node id
Object id = getNewId(destTree.getTreeNode(dropNodeKey));
destTree.addNode(dropNodeKey, draggedNode, id, state);
}
AjaxContext ac = AjaxContext.getCurrentInstance();
// Add destination tree to reRender
try {
ac.addComponentToAjaxRender(destTree);
} catch (Exception e) {
System.err.print(e.getMessage());
}
}
Thanks,
Narin
