AttributeError: QDialog object has no attribute setCentralWidget

Question

I'm trying to create a GUI with QT Designer. I've converted my .ui designer file to a .py file using the following tutorial: http://pyqt.sourceforge.net/Docs/PyQt5/designer.html.

I have the following code:

#
# Created by: PyQt5 UI code generator 5.7
#
# WARNING! All changes made in this file will be lost!
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QDialog

class Ui_ImageDialog(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(160, 200, 191, 151))
        self.pushButton.setObjectName("pushButton")
        self.pushButton_2 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_2.setGeometry(QtCore.QRect(450, 200, 191, 151))
        self.pushButton_2.setObjectName("pushButton_2")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(150, 70, 501, 101))
        palette = QtGui.QPalette()
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 255))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Active, QtGui.QPalette.WindowText, brush)
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 255))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Inactive, QtGui.QPalette.WindowText, brush)
        brush = QtGui.QBrush(QtGui.QColor(127, 127, 127))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Disabled, QtGui.QPalette.WindowText, brush)
        self.label.setPalette(palette)
        font = QtGui.QFont()
        font.setPointSize(72)
        self.label.setFont(font)
        self.label.setLayoutDirection(QtCore.Qt.LeftToRight)
        self.label.setObjectName("label")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 22))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Open Input File:"))
        self.pushButton_2.setText(_translate("MainWindow", "Run"))
        self.label.setText(_translate("MainWindow", "Happy Scraping"))

app = QApplication(sys.argv)
window = QDialog()

ui = Ui_ImageDialog()
ui.setupUi(window)

window.show()
sys.exit(app.exec_())

However, when I run this script, I get the following error:

File "/Users/tituskex/scrapeUI.py", line 42, in setupUi
MainWindow.setCentralWidget(self.centralwidget)
AttributeError: 'QDialog' object has no attribute 'setCentralWidget'

Q: Does anyone know how to fix this?

Answer 1

When you use qt-designer you can choose the type of widget you want to design:

For example you have chosen a Main Window, therefore you must implement it with QMainWindow.

#
# Created by: PyQt5 UI code generator 5.7
#
# WARNING! All changes made in this file will be lost!
import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow

class Ui_ImageDialog(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(800, 600)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(160, 200, 191, 151))
        self.pushButton.setObjectName("pushButton")
        self.pushButton_2 = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton_2.setGeometry(QtCore.QRect(450, 200, 191, 151))
        self.pushButton_2.setObjectName("pushButton_2")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(150, 70, 501, 101))
        palette = QtGui.QPalette()
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 255))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Active, QtGui.QPalette.WindowText, brush)
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 255))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Inactive, QtGui.QPalette.WindowText, brush)
        brush = QtGui.QBrush(QtGui.QColor(127, 127, 127))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Disabled, QtGui.QPalette.WindowText, brush)
        self.label.setPalette(palette)
        font = QtGui.QFont()
        font.setPointSize(72)
        self.label.setFont(font)
        self.label.setLayoutDirection(QtCore.Qt.LeftToRight)
        self.label.setObjectName("label")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 22))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "Open Input File:"))
        self.pushButton_2.setText(_translate("MainWindow", "Run"))
        self.label.setText(_translate("MainWindow", "Happy Scraping"))

app = QApplication(sys.argv)
window = QMainWindow()

ui = Ui_ImageDialog()
ui.setupUi(window)

window.show()
sys.exit(app.exec_())

If you want to implement a QDialog you must choose some of the Dialog(Dialog with Buttons Bottom, Dialog with Buttons Right or Dialog without Buttons).

Answer 2

Instead of going all the way to QtDesigner and make another ui You can go to the ui file and edit it in the Code editor and you will see that the file has the main class written in the first or second line and you can change it Here is an example.

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Form</class>
 <widget class="QWidget" name="Form">
  <property name="geometry">
  .
  .
  .
  .

Here we can change the tag's class attribute to QMainWindow so it will become

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>Form</class>
 <widget class="QMainWindow" name="Form">
  <property name="geometry">
   .
   .
   .
   .