Trigger action on completion of drag action

Question

I'm trying to allow items from a QListWidget to be dragged to a "Trash" (A subclassed widget which accepts drops and does nothing with them).

I know that if I setDropAction(Qt.MoveAction), the items I am removing from the source will be automatically deleted. This works correctly.
My problem is that I also need to trigger an action that updates other widgets who depend upon the contents of the source.

It seems to me that the dropEvent happens before any items are actually removed from the source. I'm having a terrible time trying to figure out this problem. I've thought of two possible solutions:

1. Find a way to embed the references to the actual QListWidgetItems that are being dragged in the event's QMimeData. This would allow me to do the deletions by hand, before I trigger updates.

2. Figure out how to wait until the source has been automatically cleared, but I can't find any signals that fire when items are removed from a list automatically.

Answer 1

Aha!

The key I was missing was the mimeData method. This method is called when a drag is started, and in it I am passed a list of all files being dragged.

I first built the meta object to be returned, then I deleted the files being dragged from the list, and called the refresh action that I needed.

Here's an example:

def mimeData(self, items):
    m = QMimeData()
    m.setUrls([QUrl(i.url) for i in items])

    # Clean up the list:
    [self.files.takeItem(self.files.indexFromItem(i).row()) for i in items]
    self._update_meta()

    return m