[FIXED] [1.2.1] Regression: Asynchronous Tree with DND does not expand folder

[Jose Jeria]

The following Tree loads the children asynchronously (FileServiceImpl from explorer demo is used) and allows the Tree items to be dragged into other folders.

A TreeItem will expand and loads its children when a TreeItem is dragged and hovered over a folder. This works in the 1.2 release, but fails in version 1.2.1.

public class DNDTreeTest extends LayoutContainer {
    @SuppressWarnings("unchecked")
    @Override
    public void onRender(Element parent, int index) {
        super.onRender(parent, index);

        LayoutContainer container = new LayoutContainer();
        container.setSize(280, 400);
        container.setBorders(true);
        container.setScrollMode(Scroll.AUTO);

        this.setStyleAttribute("margin", "10px");

        final FileServiceAsync service = (FileServiceAsync) Registry.get("fileservice");

        RpcProxy<FileModel, List<FileModel>> proxy = new RpcProxy<FileModel, List<FileModel>>() {
              @Override
              protected void load(FileModel loadConfig, AsyncCallback<List<FileModel>> callback) {
                  service.getFolderChildren(loadConfig, callback);
              }
        };

        TreeLoader loader = new BaseTreeLoader(proxy) {
            @Override
            public boolean hasChildren(ModelData parent) {
                return parent instanceof FolderModel;
            }
        };

        TreeStore<FileModel> store = new TreeStore<FileModel>(loader);

        final Tree tree = new Tree();
        tree.getStyle().setLeafIconStyle("icon-list");
        TreeBinder<FileModel> binder = new TreeBinder<FileModel>(tree, store);

        binder.setDisplayProperty("name");

        loader.load(null);

        TreeDragSource source = new TreeDragSource(binder);
        source.addDNDListener(new DNDListener() {
            @Override
            public void dragStart(DNDEvent e) {
                TreeItem item = tree.findItem(e.getTarget());

                if (item != null && item == tree.getRootItem().getItem(0)
                        && tree.getRootItem().getItemCount() == 1) {
                    e.doit = false;
                    e.status.setStatus(false);
                    return;
                }

                super.dragStart(e);
            }
        });

        TreeDropTarget target = new TreeDropTarget(binder);
        target.setAllowSelfAsSource(true);
        target.setFeedback(Feedback.BOTH);

        container.add(tree);
        this.add(container);
    }
}

[Jose Jeria]

Has anybody been able to reproduce this? I assume it is a regression and not an error in the code, since it works fine in 1.2

[sven]

Yes, not only to reproduce it, but also to look into it much deeper

[amundb]

Figures, I spent all day developing a work around for this issue. I had no idea this worked in 1.2, I never had to do any Drag and Drop until 1.2.1. But if you need something working now...

I had to use OnDragMove(DNDEvent event) on the TreeDropTarget instead of dragEnter on the DNDListener because the event.getTarget() on dragEnter gives you the entire Tree's Element instead of the specific tree node.

treeDropTarget = new TreeDropTarget(treeBinder) {
            protected void onDragMove(DNDEvent event) {
                processDrag(event);
                super.onDragMove(event);
            }
}

private void processDrag(DNDEvent e) {
        Tree theTree = (Tree) e.target.getComponent();
        TreeItem item = theTree.findItem(e.getTarget());
        if (item != lastTreeItem && item != null && item.isExpanded() == false) {
            lastTreeItem = item;
            FolderTreeNode model = ((BeanModel) item.getModel()).getBean();
            if (!model.isLeaf()) {
                BeanModel toBeExpanded = treeStore.findModel("id", model.getId());
                if (toBeExpanded != null)
                    treeLoader.loadChildren(toBeExpanded);
            }

            item.setExpanded(true);
        }
    }

Hope this helps.

[Jose Jeria]

@amundb: Could you please provide the complete workaround solution? lastTreeItem has not been defined in your example.

[amundb]

lastTreeItem is just a temp variable tracked by whatever class you have this code in. So somewhere in your class there is:

private TreeItem lastTreeItem;

The reason you should check this:
if (item != lastTreeItem && item != null && item.isExpanded() == false)

Is that everytime you have an active drag, and you move the mouse over your target
tree node without releasing, the process drag method will be called. So we want to keep
track of what node we are moused over, and only process this event once for the node.
If we then leave this node and mouse over a different one, then go ahead and continue to process the event.

[darrellmeyer]

A TreeItem will expand and loads its children when a TreeItem is dragged and hovered over a folder. This works in the 1.2 release, but fails in version 1.2.1.

This is fixed in SVN. Please validate.

[Jose Jeria]

I can still reproduce this.

I grabbed the source from http://code.extjs.com/svn/gxt/releases/1.2.

[negge]

This is fixed in SVN. Please validate.

I am using the trunk [r1181] and can reproduce this error when my Tree is not asynchronously loaded.

Nathan

DataReader<List<MyModel>> treeReader=new DataReader<List<MyModel>>() {
    @SuppressWarnings("unchecked")
    public List<NavigableModel> read(Object _config,Object _parent) {
        if (_parent==null) {
            return((List)grandparentStore().getModels());
        }
        if (_parent instanceof MyGrandParentModel) {
            MyGrandParentModel myGrandParent=(MyGrandParentModel)_parent;
            return((List)myGrandParentModel.getParentStore().getModels());
        }
        if (_parent instanceof MyParentModel) {
            MyParentModel myParentModel=(MyParentModel)_parent;
            return((List)myParentModel.getChildrenStore().getModels());
        }
        throw(new IllegalArgumentException("Invalid data"));
    }
};

TreeLoader<MyModel> treeLoader=new BaseTreeLoader<MyModel>(treeReader) {
    public boolean hasChildren(MyModel _parent) {
        return(_parent instanceof MyParentModel||_parent instanceof MyGrandParentModel);
    }
};

TreeStore<MyModel> treeStore=new TreeStore<MyModel>(treeLoader);
treeStore.setMonitorChanges(true);

Tree tree=new Tree();
tree.setAnimate(false);

TreeBinder<MyModel> treeBinder=new TreeBinder<MyModel>(tree,treeStore);
treeBinder.setDisplayProperty("name");

TreeDragSource source=new TreeDragSource((TreeBinder)treeBinder);
TreeDropTarget target=new TreeDropTarget((TreeBinder)treeBinder);
target.setAllowSelfAsSource(true);
target.setFeedback(Feedback.BOTH);[FONT=verdana,geneva,lucida,'lucida grande',arial,helvetica,sans-serif]

[Jose Jeria]

Is there any update on this issue?