widgets are not showing when inheriting the QMainWindow class

[rhx9]

Hi,
I created a test project in qt-creator and choosing "qt for python- window (UI) file" as a template and a QMainWindow as a base class, then added a single push button and applied a grid layout to the centralwidget but after clicking Ctrl+r to run the project I only see a blank window with no widgets.

form.ui (generated by qt creator, not modified):

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>test</class>
 <widget class="QMainWindow" name="test">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>test</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QGridLayout" name="gridLayout">
    <item row="0" column="0">
     <widget class="QPushButton" name="pushButton">
      <property name="text">
       <string>PushButton</string>
      </property>
     </widget>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>34</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

main.py (generated by qt creator, not modified):

# This Python file uses the following encoding: utf-8
import sys
import os


from PySide2.QtWidgets import QApplication, QMainWindow
from PySide2.QtCore import QFile
from PySide2.QtUiTools import QUiLoader


class test(QMainWindow):
    def __init__(self):
        super(test, self).__init__()
        self.load_ui()

    def load_ui(self):
        loader = QUiLoader()
        path = os.path.join(os.path.dirname(__file__), "form.ui")
        ui_file = QFile(path)
        ui_file.open(QFile.ReadOnly)
        loader.load(ui_file, self)
        ui_file.close()

if __name__ == "__main__":
    app = QApplication([])
    widget = test()
    widget.show()
    sys.exit(app.exec_())

note that choosing Qwidget as a base class works fine and I can see the push button without a problem, if I convert the UI file using the pyuic command it works and runs just fine, also if I load the UI file without inheriting a class it works fine as well like so:

import sys


from PySide2.QtWidgets import QApplication
from PySide2.QtUiTools import QUiLoader


if __name__ == "__main__":
    app = QApplication([])
    w = QUiLoader().load("form.ui")
    w.show()
    sys.exit(app.exec_())

[jsulm]

@rhx9 said in widgets are not showing when inheriting the QMainWindow class:

loader.load(ui_file, self)

Use https://doc.qt.io/qt-5/qmainwindow.html#centralWidget as parent:

loader.load(ui_file, self.centralWidget())

[rhx9]

@jsulm said in widgets are not showing when inheriting the QMainWindow class:

@rhx9 said in widgets are not showing when inheriting the QMainWindow class:

loader.load(ui_file, self)

Use https://doc.qt.io/qt-5/qmainwindow.html#centralWidget as parent:

loader.load(ui_file, self.centralWidget())

Nope, doesn't work. also printing self.centralWidget() returns None since it is only set after loading a UI if I'm not mistaken

[JonB]

This post is deleted!