GridRowDragger in Vaadin 21 missing?

Question

I'd like to use this "Drag and Drop Reorder of Rows in Grid"-code in Vaadin 21: https://demo.vaadin.com/sampler/#ui/drag-drop/grid-reorder-rows-html5

Unfortunately I don't find the com.vaadin.ui.components.grid.GridRowDragger<T> class in Vaadin 21.

Is there any replacement / substitution?

Answer 1

An approach is to use a class that has its own order number. When dropping an item, find the new neighbour items, update order number at all items and re-set them as items in the grid.

This is working for me with a few hundreds of items in a grid:

    grid.setSelectionMode(SelectionMode.SINGLE);
    grid.setRowsDraggable(true);
    grid.setDropMode(GridDropMode.BETWEEN);
    grid.addDragStartListener(new ComponentEventListener<GridDragStartEvent<MyItem>>() {
        @Override
        public void onComponentEvent(GridDragStartEvent<MyItem> event) {
            draggedItems = event.getDraggedItems();
        }
    });
    grid.addDragEndListener(new ComponentEventListener<GridDragEndEvent<MyItem>>() {
        @Override
        public void onComponentEvent(GridDragEndEvent<MyItem> event) {
            draggedItems = null;
        }
    });
    grid.addDropListener(new ComponentEventListener<GridDropEvent<MyItem>>() {
        @Override
        public void onComponentEvent(GridDropEvent<MyItem> event) {
            if (draggedItems != null) {
                Optional<MyItem> dropTargetItemOptional = event.getDropTargetItem();
                if (dropTargetItemOptional.isPresent()) {
                    // Find drop target item
                    MyItem dropTargetItem = dropTargetItemOptional.get();
                    int dropTargetIndex = getIndexOf(dropTargetItem);

                    // Increase order number at all following items
                    int dropTargetOrder = dropTargetItem.getOrderNumber();
                    int offset = draggedItems.size() + 1;
                    boolean droppedAboveTargetItem = event.getDropLocation() == GridDropLocation.ABOVE;
                    int numberOfItems = myItems.size();
                    for (int i = dropTargetIndex + (droppedAboveTargetItem ? 0 : 1); i < numberOfItems; i++) {
                        myItems.get(i)
                                .setOrderNumber(dropTargetOrder + i - dropTargetIndex + offset);
                    }

                    // Update order number at dragged items
                    int i = 1;
                    for (MyItem item : draggedItems) {
                        item.setOrderNumber(dropTargetOrder + i);
                        i++;
                    }
                    // Sort (and re-number) all items
                    sortByOrder(myItems);
                    grid.setItems(myItems);
                }
            }
            draggedItems = null;
        }
    });