Switching between windows PyQt designer

Question

I have been trying to develop a software in PyQt5.

I have 3 windows: 1) login 2) dashboard 3) appointments

Now I can navigate properly from login -> dashboard -> appointments perfectly. But when I press pushbutton for back from appointments, it doesn't come back to dashboard.

But if I go from dashboard->appointments, the pushbutton works for 1 time.

I have removed irrelevant lines from the code to make analysis simpler.

login window class:

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):
        self.MainWindow = MainWindow

    def retranslateUi(self, MainWindow):
        self.pushButton.clicked.connect(self.next)
 
    def next(self):
        ui = Ui_MainWindow2()
        ui.setupUi(self.MainWindow)
        self.MainWindow.show()

dashboard window class:

class Ui_MainWindow2(object):

    def setupUi(self, MainWindow):
        self.MainWindow = MainWindow

    def retranslateUi(self, MainWindow):
        self.pushButton.clicked.connect(self.next)
 
    def next(self):
        ui = Ui_MainWindow3()
        ui.setupUi(self.MainWindow)
        self.MainWindow.show()

appointment window class:

class Ui_MainWindow3(object):

    def setupUi(self, MainWindow):
        self.MainWindow = MainWindow

    def retranslateUi(self, MainWindow):
        self.pushButton.clicked.connect(self.back)
 
    def back(self):
        ui = Ui_MainWindow2()
        ui.setupUi(self.MainWindow)
        self.MainWindow.show()

Application starts from file login.py which has:

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

The forward navigation always work, the backward one keeps failing...

Any help or suggestions will be very welcome...

Answer 1

Turns out I was writing the next or back function slightly differently than it should have been. The next and back functions should have been like this:

def next(self):
        self.window = QtWidgets.QMainWindow()
        self.ui = Ui_MainWindow2()
        self.ui.setupUi(self.window)
        self.oldWindow.hide()
        self.window.show()

where self.oldWindow is the reference to the original window of the class enclosing the function next. This is also same for the back function.