Question

I have a MainWindow that looks like this:

def __init__(self, parent = None):

    QMainWindow.__init__(self, parent)
    self.setupUi(self)
    self.showMaximized()

    menu=mainMenu.MainMenu()

    classification=classificationMain.ClassificationMain()

    self.stackedWidget.addWidget(menu)
    self.stackedWidget.addWidget(classification)

    self.stackedWidget.setCurrentWidget(menu)
    self.stackedWidget.showFullScreen()

    #connections

    menu.pushButton.clicked.connect(self.showClassification)
    classification.backButton.clicked.connect(self.showMainWindow)

def showClassification(self ):
    self.stackedWidget.setCurrentIndex(3)

def showMainWindow(self):
    self.stackedWidget.setCurrentIndex(2)

The MainWindows waits for signal from the rest of the dialogs. Now, the Classification dialog has another StackedWidget in it, since it works as a main window for an important part of the application. It looks like:

class ClassificationMain(QDialog, Ui_Dialog):

def __init__(self, parent = None):

    QDialog.__init__(self, parent)
    self.setupUi(self)
    choose=choosePatient.ChoosePatient()
    self.stackedWidget.addWidget(choose)
    self.stackedWidget.setCurrentWidget(choose)

Now, I want to reload the data inside ChoosePatient every time the button “Show Classification” from MainMenu is clicked, but now the data is loaded only once in the line classification=classificationMain.ClassificationMain() of MainWindow.

I was thinking I had to connect a slot inside ChoosePatient with the click of “Show Classification” button inside MainMenu, but I would need an instance of MainMenu, which is not possible.

How can a method of ChoosePatient can be execute every time the button in the “parent” window is clicked? (also, please tell me if this is not the right way to work with pyqt windows)

Answer 1

You need to save references to your composed widgets, and also to expose some public methods to the parents:

class ClassificationMain(QDialog, Ui_Dialog):

    def __init__(self, parent = None):

        QDialog.__init__(self, parent)
        self.setupUi(self)
        self.chooseWidget=choosePatient.ChoosePatient()
        self.stackedWidget.addWidget(self.chooseWidget)
        self.stackedWidget.setCurrentWidget(self.chooseWidget)

    def reloadPatients(self):
        # whatever your operation should be on the ChoosePatient
        self.chooseWidget.reload()


# MAIN WINDOW
def __init__(self, parent = None):
    ...
    self.classification=classificationMain.ClassificationMain()
    self.stackedWidget.addWidget(self.classification)
    ...
    #connections
    menu.pushButton.clicked.connect(self.showClassification)

def showClassification(self ):
    self.stackedWidget.setCurrentIndex(3)
    self.classification.reloadPatients()

You could also just skip the reloadPatients method and connect to the ChoosePatient directly if you want:

def showClassification(self ):
    self.stackedWidget.setCurrentIndex(3)
    self.classification.chooseWidget.reload()

My personal opinion is to make your custom classes wrap up the internal functionality nicely so that you only need to interface with it over the custom class, and not dig into its internals. That way you can change how it works inside without breaking the main window.