How to overwrite QDialog.accept()?

Question

I have a Mainwindow that is opening a dialog on the press of a pushbutton. I want to override accept function of the dialog so I could implement some custom functionality that should be executed before dialog is accepted. Here is the example code of my mainwindow.

from PySide2 import QtCore, QtGui, QtWidgets
from add_new import Add_new_dialog
import sys

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(500, 100)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushNew_Bed = QtWidgets.QPushButton(self.centralwidget)
        self.pushNew_Bed.setObjectName("pushNew_Bed")
        self.pushNew_Bed.resize(QtCore.QSize(500,100))
        self.pushNew_Bed.clicked.connect(self.on_add_new_clicked)



    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushNew_Bed.setText(_translate("MainWindow", "Add New Bed"))



    def on_add_new_clicked(self):
        Dialog = QtWidgets.QDialog()
        Dialog.ui = Add_new_dialog()
        Dialog.ui.setupUi(Dialog)
        #dialog.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        retValue = Dialog.exec_()
        if retValue == 1:
            print("Accepted")#dialog.calendarWidget.selectedDate())



if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

And here is the dialog.

from PySide2 import QtCore, QtGui, QtWidgets
import sys

class Add_new_dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName("Dialog")
        Dialog.resize(400, 300)
        Dialog.setMinimumSize(QtCore.QSize(400, 300))
        Dialog.setMaximumSize(QtCore.QSize(400, 300))

        self.buttonBox = QtWidgets.QDialogButtonBox(Dialog)
        self.buttonBox.setOrientation(QtCore.Qt.Horizontal)
        self.buttonBox.setStandardButtons(QtWidgets.QDialogButtonBox.Cancel|QtWidgets.QDialogButtonBox.Ok)
        self.buttonBox.setObjectName("buttonBox")


        self.retranslateUi(Dialog)
        #self.buttonBox.accepted.connect(Dialog.accept)
        self.buttonBox.accepted.connect(self.custom_func)
        self.buttonBox.rejected.connect(Dialog.reject)
        QtCore.QMetaObject.connectSlotsByName(Dialog)


    def retranslateUi(self, Dialog):
        _translate = QtCore.QCoreApplication.translate
        Dialog.setWindowTitle(_translate("Dialog", "Dialog"))


    def custom_func(self):
        Dialog.accept()
        print("custom func")


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    Dialog = QtWidgets.QDialog()
    ui = Add_new_dialog()
    ui.setupUi(Dialog)
    Dialog.show()
    sys.exit(app.exec_())

If I launch the dialog standalone everything works as expected. However if I call for it from the mainwindow, I, predictably, get an error.

    Dialog.accept()
NameError: name 'Dialog' is not defined

I've tried adding the following code to dialog to overwrite the accept function:

def accept(self):
    self.custom_func()
    Dialog.done(QtWidgets.QDialog.Accepted)

And binding the button to that function

self.buttonBox.accepted.connect(self.accept)
self.buttonBox.rejected.connect(Dialog.reject)

Again, predictably I get the same result. Reading the documentation didn't help much. Any help is greatly appreciated and I apologize for this noobish question, but I'm a complete beginner with gui. Thank you in advance.

Answer 1

_{You should not modify the class generated by Qt Designer so you must regenerate the.py (for more information read here ) so I will assume that class Ui_MainWindow and Add_new_dialog belong to file mainwindow_ui.py and add_new_dialog_ui.py , respectively.}

Considering the above, you should override the method of the class that inherits QDialog:

main.py

from PySide2 import QtCore, QtGui, QtWidgets

from mainwindow_ui import Ui_MainWindow
from add_new_dialog_ui import Add_new_dialog


class AddDialog(QtWidgets.QDialog, Add_new_dialog):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setupUi(self)

    def accept(self):
        print("custom func")
        super().accept()


class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setupUi(self)
        self.pushNew_Bed.clicked.connect(self.on_add_new_clicked)

    def on_add_new_clicked(self):
        dialog = AddDialog()
        retValue = dialog.exec_()
        if retValue == QtWidgets.QDialog.Accepted:
            print("Accepted")


if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())