PyQt5 QTreeWidget in layout showing an extra column outside the widget

Question

I am trying to write a PyQt5 widget which will be a basic preset manager inside an application. I am trying to use the QTreeWidget to display the structure of each type. I have this weird issue, where I see an extra QTreeWidget with a column named "1" outside my QTreeWidget. I have attached a picture (sorry, I could not take a screenshots) and the code. I have also noticed that this does not happen if I don't use classes.

Here's my test code showing the problem:

import sys
from PyQt5 import QtCore, QtGui, QtWidgets

class MyTree(QtWidgets.QTreeWidget):
    def __init__(self, parent = None):
        super(self.__class__, self).__init__(parent)

        boxLayout = QtWidgets.QVBoxLayout()

        treeWidget = QtWidgets.QTreeWidget()
        treeWidget.setHeaderLabels(['Preset Name'])
        treeWidget.setColumnCount(1)
        items = []
        for i in range(10):
            items.append(QtWidgets.QTreeWidgetItem(["item {0}".format(i)]))
        treeWidget.insertTopLevelItems(0, items)

        boxLayout.addWidget(treeWidget)
        self.setLayout(boxLayout)

if __name__ == '__main__':

    app = QtWidgets.QApplication(sys.argv)
    w = MyTree()
    w.show()

    sys.exit(app.exec_())

That's what I see:

My best guess that it's the layout that's causing it, because if I just create the QTreeWidget like so:

import sys
from PyQt5 import QtCore, QtGui, QtWidgets

app = QtWidgets.QApplication(sys.argv)

treeWidget = QtWidgets.QTreeWidget()
treeWidget.setHeaderLabels(['Preset Name'])
treeWidget.setColumnCount(1)
items = []
for i in range(10):
    items.append(QtWidgets.QTreeWidgetItem(["item {0}".format(i)]))
treeWidget.insertTopLevelItems(0, items)
treeWidget.show()

sys.exit(app.exec_())

That's what I see:

Any ideas how to get it showing like the second image, from a class?

Any help is greatly appreciated

score 1 · Accepted Answer · answered May 23 '20 at 23:50

The error is simple: Your window (MyTree) is an empty QTreeWidget that has another QTreeWidget inside, so "1" belongs to the empty QTreeWidget.

There are 2 possible solutions:

No user as base class to QTreeWidget

class MyTree(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(self.__class__, self).__init__(parent)

        treeWidget = QtWidgets.QTreeWidget()
        treeWidget.setHeaderLabels(["Preset Name"])
        treeWidget.setColumnCount(1)
        items = []
        for i in range(10):
            items.append(QtWidgets.QTreeWidgetItem(["item {0}".format(i)]))
        treeWidget.insertTopLevelItems(0, items)

        boxLayout = QtWidgets.QVBoxLayout(self)
        boxLayout.addWidget(treeWidget)

Do not nest a new QTreeWidget

class MyTree(QtWidgets.QTreeWidget):
    def __init__(self, parent=None):
        super(self.__class__, self).__init__(parent)

        self.setHeaderLabels(["Preset Name"])
        self.setColumnCount(1)
        items = []
        for i in range(10):
            items.append(QtWidgets.QTreeWidgetItem(["item {0}".format(i)]))
        self.insertTopLevelItems(0, items)

Both methods work! Thank you very much! I did not notice that using the QTreeWidget as a base class was creating the nesting! — vaco, May 24 '20 at 02:52

PyQt5 QTreeWidget in layout showing an extra column outside the widget

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