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Thread: How can I properly implement QSortFilterProxyModel.parent to handle a virtual column?

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    Qt products
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    Question How can I properly implement QSortFilterProxyModel.parent to handle a virtual column?

    I have the following working code, which opens a QFileDialog with an extra column that shows the file name again (pointless, I know, but it’s a result of simplifying my issue):

    Qt Code:
    1. from PySide2 import QtCore, QtWidgets
    2.  
    3.  
    4. class MyProxyModel(QtCore.QSortFilterProxyModel):
    5.  
    6. def __init__(self, parent=None):
    7. super(MyProxyModel, self).__init__(parent)
    8. self._parents = {}
    9.  
    10. def mapToSource(self, index):
    11. if index.column() == 4:
    12. return QtCore.QModelIndex()
    13. return super(MyProxyModel, self).mapToSource(index)
    14.  
    15. def columnCount(self, index):
    16. return 5
    17.  
    18. def data(self, index, role=QtCore.Qt.DisplayRole):
    19. if role == QtCore.Qt.DisplayRole and index.column() == 4:
    20. return self.index(index.row(), 0, self._parents[index]).data(role)
    21. return super(MyProxyModel, self).data(index, role)
    22.  
    23. def headerData(self, section, orientation, role=QtCore.Qt.DisplayRole):
    24. if section == 4 and orientation == QtCore.Qt.Horizontal and role == QtCore.Qt.DisplayRole:
    25. return 'My Column'
    26. return super(MyProxyModel, self).headerData(section, orientation, role)
    27.  
    28. def index(self, row, column, parent=QtCore.QModelIndex()):
    29. if column == 4:
    30. index = self.createIndex(row, column)
    31. self._parents[index] = parent
    32. return index
    33. return super(MyProxyModel, self).index(row, column, parent)
    34.  
    35. def parent(self, index):
    36. if index.column() == 4:
    37. return QtCore.QModelIndex()
    38. return super(MyProxyModel, self).parent(index)
    39.  
    40.  
    41. QtWidgets.QApplication([])
    42. dialog = QtWidgets.QFileDialog()
    43. dialog.setOption(dialog.DontUseNativeDialog, True)
    44. dialog.setProxyModel(MyProxyModel(dialog))
    45. dialog.exec_()
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    As you can see, parent() is returning an invalid index for items of column 4, and instead I’m retrieving the actual parent inside data(), which isn’t ideal. But if I try the following, it exits with an access violation:

    Qt Code:
    1. (...)
    2. def data(self, index, role=QtCore.Qt.DisplayRole):
    3. if role == QtCore.Qt.DisplayRole and index.column() == 4:
    4. # Either return causes access violation.
    5. return self.index(index.row(), 0, self.parent(index)).data(role)
    6. return self.index(index.row(), 0, index.parent()).data(role)
    7. return index.sibling(index.row(), 0).data(role)
    8. return super(MyProxyModel, self).data(index, role)
    9. (...)
    10. def parent(self, index):
    11. if index.column() == 4:
    12. return self._parents[index]
    13. return super(MyProxyModel, self).parent(index)
    14. (...)
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    I also tried leveraging QModelIndex’s internal pointer, with the same result (access violation):

    Qt Code:
    1. # No __init__() defined; data() exactly like above.
    2. (...)
    3. def index(self, row, column, parent=QtCore.QModelIndex()):
    4. if column == 4:
    5. return self.createIndex(row, column, parent)
    6. return super(MyProxyModel, self).index(row, column, parent)
    7.  
    8. def parent(self, index):
    9. if index.column() == 4:
    10. return index.internalPointer()
    11. return super(MyProxyModel, self).parent(index)
    12. (...)
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    Pretty sure I’m missing something, but I can’t figure out what it is…
    Last edited by Unai; 1st September 2021 at 18:11.

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