Loading UI file with QWebengine through class using PyQt

I’m trying to load a UI file using PyQt5.uic.loadUi which has QWebEngineView, but my code currently loads a blank QT form.

It was working before until I changed the way classes were referencing each other. I’m new to working with classes and cannot understand the correct use of self and parent.

import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
from PyQt5.QtWidgets import *
from PyQt5.QtWebEngineWidgets import QWebEngineView

html = """
<!DOCTYPE html><html><head></head><body>
<div id="output">Test page</div>
</body></html>
"""
text1 = 'demo text'

class Ui(QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        uic.loadUi('demoweb.ui', self)
        ctr = self.findChild(QWidget,"webViewContainer")
        self.browser = ctr.findChild(QWebEngineView,"webEngineView")
        self.edit = self.findChild(QLineEdit,"lineEdit")

class Window(QtWidgets.QWidget):
    def __init__(self, parent = None):
        super().__init__(parent)
        ui = Ui()
        self._ui = ui
        ui.browser.setHtml(html)
        page = ui.browser.page()
        page.loadFinished.connect(self.onLoadFinished)
        ui.edit.setText(text1)
        self._ready = False
    
    def onLoadFinished(self):
        #code to be added
        return

if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    window = Window()
    window.show()
    app.exec()

JavaScript
​x
 
import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
from PyQt5.QtWidgets import *
from PyQt5.QtWebEngineWidgets import QWebEngineView
​
html = """
<!DOCTYPE html><html><head></head><body>
<div id="output">Test page</div>
</body></html>
"""
text1 = 'demo text'
​
class Ui(QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        uic.loadUi('demoweb.ui', self)
        ctr = self.findChild(QWidget,"webViewContainer")
        self.browser = ctr.findChild(QWebEngineView,"webEngineView")
        self.edit = self.findChild(QLineEdit,"lineEdit")
​
class Window(QtWidgets.QWidget):
    def __init__(self, parent = None):
        super().__init__(parent)
        ui = Ui()
        self._ui = ui
        ui.browser.setHtml(html)
        page = ui.browser.page()
        page.loadFinished.connect(self.onLoadFinished)
        ui.edit.setText(text1)
        self._ready = False
    
    def onLoadFinished(self):
        #code to be added
        return
​
if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    window = Window()
    window.show()
    app.exec()
​

demoweb.ui file:

<?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>746</width><height>462</height></rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QLineEdit" name="lineEdit">
    <property name="geometry">
     <rect><x>21</x><y>361</y><width>691</width><height>22</height></rect>
    </property>
   </widget>
   <widget class="QWidget" name="webViewContainer" native="true">
    <property name="geometry">
     <rect><x>10</x><y>10</y><width>711</width><height>331</height></rect>
    </property>
    <layout class="QVBoxLayout" name="verticalLayout">
     <item>
      <widget class="QWebEngineView" name="webEngineView">
       <property name="url">
        <url>
         <string>about:blank</string>
        </url>
       </property>
      </widget>
     </item>
    </layout>
   </widget>
  </widget>
 </widget>
 <customwidgets>
  <customwidget>
   <class>QWebEngineView</class>
   <extends>QWidget</extends>
   <header location="global">QtWebEngineWidgets/QWebEngineView</header>
  </customwidget>
 </customwidgets>
 <resources/>
 <connections/>
</ui>

JavaScript
 
<?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>746</width><height>462</height></rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QLineEdit" name="lineEdit">
    <property name="geometry">
     <rect><x>21</x><y>361</y><width>691</width><height>22</height></rect>
    </property>
   </widget>
   <widget class="QWidget" name="webViewContainer" native="true">
    <property name="geometry">
     <rect><x>10</x><y>10</y><width>711</width><height>331</height></rect>
    </property>
    <layout class="QVBoxLayout" name="verticalLayout">
     <item>
      <widget class="QWebEngineView" name="webEngineView">
       <property name="url">
        <url>
         <string>about:blank</string>
        </url>
       </property>
      </widget>
     </item>
    </layout>
   </widget>
  </widget>
 </widget>
 <customwidgets>
  <customwidget>
   <class>QWebEngineView</class>
   <extends>QWidget</extends>
   <header location="global">QtWebEngineWidgets/QWebEngineView</header>
  </customwidget>
 </customwidgets>
 <resources/>
 <connections/>
</ui>
​

Answer

This has been resolved after following suggestions from musicmante

Thanks eyllanesc, your suggestion also resolved the problem but was no longer required in the simplified code.

Working code below

import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
from PyQt5.QtWidgets import *
from PyQt5.QtWebEngineWidgets import QWebEngineView

html = """
<!DOCTYPE html><html><head></head><body>
<div id="output">Test page</div>
</body></html>
"""
text1 = 'demo text'

class Ui(QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        uic.loadUi('demoweb.ui', self)
        ctr = self.findChild(QWidget,"webViewContainer")
        self.browser = ctr.findChild(QWebEngineView,"webEngineView")
        self.edit = self.findChild(QLineEdit,"lineEdit")

class Window(QtWidgets.QMainWindow):
    def __init__(self, parent = None):
        super().__init__(parent)
        uic.loadUi('demoweb.ui', self)
        self.webEngineView.setHtml(html)
        page = self.webEngineView.page()
        page.loadFinished.connect(self.onLoadFinished)
        self.lineEdit.setText(text1)
        self._ready = False
    
    def onLoadFinished(self):
        #code to be added
        return

if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    window = Window()
    window.show()
    app.exec()

JavaScript
 
import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
from PyQt5.QtWidgets import *
from PyQt5.QtWebEngineWidgets import QWebEngineView
​
html = """
<!DOCTYPE html><html><head></head><body>
<div id="output">Test page</div>
</body></html>
"""
text1 = 'demo text'
​
class Ui(QMainWindow):
    def __init__(self):
        super(Ui, self).__init__()
        uic.loadUi('demoweb.ui', self)
        ctr = self.findChild(QWidget,"webViewContainer")
        self.browser = ctr.findChild(QWebEngineView,"webEngineView")
        self.edit = self.findChild(QLineEdit,"lineEdit")
​
class Window(QtWidgets.QMainWindow):
    def __init__(self, parent = None):
        super().__init__(parent)
        uic.loadUi('demoweb.ui', self)
        self.webEngineView.setHtml(html)
        page = self.webEngineView.page()
        page.loadFinished.connect(self.onLoadFinished)
        self.lineEdit.setText(text1)
        self._ready = False
    
    def onLoadFinished(self):
        #code to be added
        return
​
if __name__ == "__main__":
    app = QtWidgets.QApplication([])
    window = Window()
    window.show()
    app.exec()
​

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Answer