PySide2 (Qt for Python) how to load a .ui file in a QMainWindow subclass

Question

I'm trying to use Qt Creator and Qt for Python to create a quick prototype for a new application. However, the code generated by the wizard doesn't make much sense to me. This is the main.py file generated by Qt Creator:

# 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 MyMainWindow(QMainWindow):
    def __init__(self):
        super(MyMainWindow, 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 = MyMainWindow()
    widget.show()
    sys.exit(app.exec_())

and this is a simple form.ui , with just a push button:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MyMainWindow</class>
 <widget class="QMainWindow" name="MyMainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MyMainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <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>22</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

I just don't understand the purpose of the load_ui function inside the MyMainWindow class. I know that PyQt5 can load a .ui file during the initialization of a widget using the uic module. As far as I know, this is not possible with Qt for Python. Am I missing something? I'm using Qt Creator 4.13.

Answer 1

I found a workaround to the original problem, as it seems that the autogenerated code doesn't work as supposed. This answer provides a way to mimic the functionality of PyQt uic module in PySide.