Embeding PyQtGraph in Qt-Designer using PySide2

Question

I can't get PyQtGraph to work using PySide2 and a .ui file where I promoted a QWidget to a PlotWidget in Qt-Designer. It works fine when I use PyQt5, but using PySide2, I get the following message :

    Qt WebEngine seems to be initialized from a plugin. Please set Qt::AA_ShareOpenGLContexts using >QCoreApplication::setAttribute before constructing QGuiApplication.
    "QFormBuilder was unable to create a custom widget of the class 'PlotWidget'; defaulting to base class 'QWidget'."
    Traceback (most recent call last):
      File "test_widget3.py", line 13, in <module>
        window.graphWidget.plot([1,5,10], [1,2,7])
    AttributeError: 'PySide2.QtWidgets.QWidget' object has no attribute 'plot'

Code:

import sys
from PySide2 import QtCore, QtGui, QtWidgets
from PySide2.QtUiTools import QUiLoader
from pyqtgraph import PlotWidget, plot
import pyqtgraph as pg

app = QtWidgets.QApplication(sys.argv)
loader = QUiLoader()
window = loader.load("pyqtgraph_window.ui")
window.graphWidget.plot([1,5,10], [1,2,7])

window.show()
app.exec_()

With PyQt5 (it works):

import sys
from PyQt5 import QtWidgets, uic
from pyqtgraph import PlotWidget, plot
import pyqtgraph as pg

app = QtWidgets.QApplication(sys.argv)
window = uic.loadUi("pyqtgraph_window.ui")
window.graphWidget.plot([1,5,10], [1,2,7])

window.show()
app.exec_()

The .ui:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <layout class="QGridLayout" name="gridLayout">
    <item row="0" column="0">
     <widget class="PlotWidget" name="graphWidget" native="true"/>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>21</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <customwidgets>
  <customwidget>
   <class>PlotWidget</class>
   <extends>QWidget</extends>
   <header>pyqtgraph</header>
   <container>1</container>
  </customwidget>
 </customwidgets>
 <resources/>
 <connections/>
</ui>

I use the last development version of PyQtGraph from Github and PySide2 v5.12 Thank you if you can help!

Answer 1

loadUi accesses classes using names dynamically, that concept does not exist in C++ so QUiLoader has this limitation so the solution is to indicate the conversion explicitly override the createWidget method:

import os
import sys

from PySide2 import QtCore, QtGui, QtWidgets, QtUiTools
import pyqtgraph as pg


CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))


class UiLoader(QtUiTools.QUiLoader):
    def createWidget(self, className, parent=None, name=""):
        if className == "PlotWidget":
            return pg.PlotWidget(parent=parent)
        return super().createWidget(className, parent, name)


if __name__ == "__main__":

    app = QtWidgets.QApplication(sys.argv)
    loader = UiLoader()
    window = loader.load(os.path.join(CURRENT_DIR, "pyqtgraph_window.ui"))
    window.graphWidget.plot([1, 5, 10], [1, 2, 7])
    window.show()
    sys.exit(app.exec_())