How to override PySide2 widget's method generated by Qt Designer?

Question

I'm trying to learn PySide2 by creating a mimic executable like powerrename tool in powertoys.

After successfully loading the Ui_PowerRenameDialog, which is generated from a .ui file created by Qt Designer.

I encountered an error trying to accomplish a functionality which can let users drag and drop files from Windows Explorer to the QTreeWidget embedded in the .ui file.

Here is my full code:

import sys
from PySide6 import QtWidgets
from PySide6 import QtCore
from ui_powerRename import Ui_PowerRenameDialog

class MyPowerRenameDialog(QtWidgets.QDialog):
    def __init__(self,parent=None):
        super().__init__(parent)

        self.ui = Ui_PowerRenameDialog()
        self.ui.setupUi(self)

        self.modify_ui()
        self.create_connections()


    def modify_ui(self):
        self.ui.previewTreeWidget.setAcceptDrops(True)

        def dragEnterEvent(self,evt):
            if evt.mimeData().hasUrls():
                evt.accept()
            else:
                evt.ignore()

        def dropEvent(self,evt):
            for url in evt.mimeData().urls():
                newItem = QtWidgets.QTreeWidgetItem(url)
                self.addTopLevelItem(newItem)

        self.ui.previewTreeWidget.dragEnterEvent = dragEnterEvent
        self.ui.previewTreeWidget.dropEvent = dropEvent

        items = QtWidgets.QTreeWidgetItemIterator(self.ui.previewTreeWidget)
        for item in items:
            item.value().setFlags(item.value().flags()|QtCore.Qt.ItemIsUserCheckable)
            item.value().setCheckState(0,QtCore.Qt.Checked)

    def create_connections(self):
        self.ui.cancelButton.clicked.connect(self.close)


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)

    window = MyPowerRenameDialog()
    window.show()

    sys.exit(app.exec_())

================================================================

Here is what I achieved so far (the red region is the QTreeWidget): The executable snapshot:

As you can see, I tried to overload the dragEnterEvent and dropEvent methods of the QTreeWidget object. The most important part of the overriding code is showed below:

def dragEnterEvent(self,evt):
    if evt.mimeData().hasUrls():
        evt.accept()
    else:
        evt.ignore()
def dropEvent(self,evt):
    for url in evt.mimeData().urls():
        newItem = QtWidgets.QTreeWidgetItem(url)
        self.addTopLevelItem(newItem)

self.ui.previewTreeWidget.dragEnterEvent = dragEnterEvent
self.ui.previewTreeWidget.dropEvent = dropEvent

===============================================================

The problem is when trying to drag and drop any content from explorer to the QTreeWidget instance, I got a TypeError

TypeError: dragEnterEvent() missing 1 required positional argument: 'evt'.

I tried to search for similar questions.One potential solution is to use installEventFilter .But it only leads me to more errors.

I mean the PySide2 document is really a mess, I can't get any useful information from their poorly formatted doc.

There are only few examples in the doc.And most of them are directly copied from the C++ version, not even changed to Python syntax.

Any idea on how to achieve that Functionality?

And is there any suggested way to learn PySide2?

Answer 1

The error comes from the fact that dragEnterEvent and dropEvent are not bound to a class (because they are nested into another function), that means that self is not automatic, this is why when it is called it expects two parameters, self and evt , but the Qt framework only passes evt .

To modify the behevior of Ui_PowerRenameDialog you should create a subclass of Ui_PowerRenameDialog and implement the two event methods in that subclass