Treeview Drag and Drop row with multiple columns issue on root index

alom

Hi,
I have a treeview/QStandardItemModel with a dragDropMode set to InternalMove and a selectionBehavoir set to SelectRows. The model has three columns. The expected behavior from the user is to move the three columns in a row as a whole and rearrange the tree hierarchy as needed.

Everything works as expected when dragging and dropping a row from column 0 on top of anther column 0. I've set the items flags on the column 1/2 items not to accept drops. The issue comes when dragging from a row to the root Item on the model and dropping in on column 1 or 2. This causes the model to create extra columns and places column 0 data in one the incorrect columns.

How can I treat the selected row and all its items drop to always drop on column 0, when dropping on the root index?
Do I have to re implement one of the dragDrop functions on the QStandardItemModel?

Thanks

SGaist

Hi,

What version of Qt are you using ?
On what OS ?
Can you provide a minimal compilable example that shows that behaviour ?

alom

Hi SGaist,
Sure, I'm on Windows 10 pro, Pyside2 v5.13.2, py3.7.6
I was hoping to post here without python code to get more eyes on this issue than in python forum, I'm sure some of the c++ guys have ran into this before.

So you can drop a "child" index under any parent and root index. The parents can be drop in each other. The issue is when dropping a child or parent on the root index on column 1 or 2.


import sys
from PySide2 import QtWidgets, QtGui
from PySide2.QtCore import Qt


class SnippetTreeView(QtWidgets.QTreeView):

    def __init__(self, parent=None):
        super(SnippetTreeView, self).__init__(parent)
        self.setContextMenuPolicy(Qt.CustomContextMenu)
        self.setDragEnabled(False)
        self.setDragDropOverwriteMode(False)
        self.setDragDropMode(QtWidgets.QAbstractItemView.InternalMove)
        self.setAlternatingRowColors(True)
        self.setSelectionMode(QtWidgets.QAbstractItemView.ExtendedSelection)
        # self.setSortingEnabled(True)
        self.header().setStretchLastSection(True)
        self.setSelectionBehavior(QtWidgets.QAbstractItemView.SelectRows)


def create_tag_color_items():
    item_tag = QtGui.QStandardItem('tag')
    item_tag.setDropEnabled(False)
    item_color = QtGui.QStandardItem('color')
    item_color.setDropEnabled(False)
    return item_tag, item_color


def add_items(model):
    headers = [
        'Name',
        'Tag',
        'Color',
    ]
    names = [
        'child-0',
        'child-1',
    ]

    model.setHorizontalHeaderLabels(headers)
    model.setColumnCount(len(headers))

    for num in range(2):
        parent_item = QtGui.QStandardItem('parent-yesDrops-' + str(num))
        parent_item.setDropEnabled(True)
        item_tag, item_color = create_tag_color_items()

        for name in names:
            child_item = QtGui.QStandardItem(name + '-noDrops' )
            child_item.setDropEnabled(False)
            ch_item_tag, ch_item_color = create_tag_color_items()
            parent_item.appendRow([child_item, ch_item_tag, ch_item_color])

        model.appendRow([parent_item, item_tag, item_color])


if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    tree = SnippetTreeView()
    model = QtGui.QStandardItemModel()
    add_items(model)
    tree.setModel(model)
    tree.show()
    rec = app.exec_()
    sys.exit(rec)

alom

I did see the canDropMineData function in the model.
How correct/safe is this approach? Am I missing any important handing of other information floating around when doing this?

I just return a false bool on any column greater than 0.

class DropModel(QtGui.QStandardItemModel):
    def __init__(self, parent=None):
        super(DropModel, self).__init__(parent)

    def canDropMimeData(self, data, action, row, column, parent):
        if column > 0:
            return False
        return QtGui.QStandardItemModel().canDropMimeData(data, action, row, column, parent)

SGaist

What about subclassing QStandardItemModel like that:

class MyModel(QtGui.QStandardItemModel):
    def dropMimeData(self, data, action, row, column, parent):
        return super().dropMimeData(data, action, row, 0, parent)

?

alom

Oh very nice!
I think that was what I was looking for. Feels much cleaner.
Thanks @SGaist !

Solved Treeview Drag and Drop row with multiple columns issue on root index