Prevent rows from being dropable when using draggable feature

[Autoflow]

Summary
I'd like to prevent rows from being dropable on some specific rows when using the draggable feature.

Version
version 4.21.22

Additional context
To prevent rows being dropable on some other target rows i tried following:

grid.on('drag', ev => {
if(!ev.appended) return false;
})

and

grid.on('drag', ev => {
if(!ev.appended) ev.stop();
})

In both cases i was not able to stop dropping on the target row.
As i use a materialized path data model and not a nested model my goal is to only drop appended rows as child nodes.

Is there an easy way to achive this?

[HIMZ5221]

The drag event cannot block the drop action because it only fires while the item is being dragged.
It does not control the final drop target.

To prevent drops on certain rows or to allow only appended drops, you should use the drop event (or beforeDrop depending on the library).

The drop event provides the final destination row and whether the action is an append, so you can stop it cleanly.

Here’s an example:

grid.on('drop', ev => {
  const { instance, rowKey, targetRowKey, appended, stopped, updateRows } = ev;

  // 1) Block dropping on specific rows
  const targetRow = grid.getRow(targetRowKey);
  if (targetRow && targetRow.blockDrop) {
    ev.stop();   // Cancel the drop
    return;
  }

  // 2) Allow only "append as child" behavior (for materialized path)
  if (!appended) {
    ev.stop();   // Prevent moving to the same level or siblings
    return;
  }
});