Unable to close the GUI application

问题:

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(277, 244)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 22))
        self.menubar.setObjectName("menubar")
        self.menuFile = QtWidgets.QMenu(self.menubar)
        self.menuFile.setObjectName("menuFile")
        MainWindow.setMenuBar(self.menubar)
        self.actionQuit = QtWidgets.QAction(MainWindow)
        self.actionQuit.setObjectName("actionQuit")
        self.actionQuit.setShortcut("Ctrl+Q")
        self.actionQuit.setStatusTip("Quit the application")
        self.actionQuit.triggered.connect(MainWindow.closeEvent)
        self.menuFile.addAction(self.actionQuit)
        self.menubar.addAction(self.menuFile.menuAction())
        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)
        MainWindow.show()

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.menuFile.setTitle(_translate("MainWindow", "File"))
        self.actionQuit.setText(_translate("MainWindow", "Quit"))

class MyWindow(QtWidgets.QMainWindow):

    def closeEvent(self, event):
        print(event)
        result = QtWidgets.QMessageBox.question(self,
                      "Confirm Exit...",
                      "Are you sure you want to exit ?",
                      QtWidgets.QMessageBox.Yes| QtWidgets.QMessageBox.No)
        event.ignore()
        print(result)
        if result == QtWidgets.QMessageBox.Yes:
            event.accept()

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

When i am trying to close the application using the Ctrl+Q shortcut the MessageBox pops up for the question and when i click on either of the choice i get

AttributeError: 'bool' object has no attribute 'ignore'

Where have i been wrong?

回答1:

You should not directly call the closeEvent() method (or the methods that xxxEvent) since this is called by internal elements of Qt through the event-loop, instead you should use the close() method to indirectly invoke closeEvent():

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):

    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(277, 244)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 22))
        self.menubar.setObjectName("menubar")
        self.menuFile = QtWidgets.QMenu(self.menubar)
        self.menuFile.setObjectName("menuFile")
        MainWindow.setMenuBar(self.menubar)
        self.actionQuit = QtWidgets.QAction(MainWindow)
        self.actionQuit.setObjectName("actionQuit")
        self.actionQuit.setShortcut("Ctrl+Q")
        self.actionQuit.setStatusTip("Quit the application")
        self.menuFile.addAction(self.actionQuit)
        self.menubar.addAction(self.menuFile.menuAction())
        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.menuFile.setTitle(_translate("MainWindow", "File"))
        self.actionQuit.setText(_translate("MainWindow", "Quit"))

class MyWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MyWindow, self).__init__(parent)
        self.setupUi(self)
        self.actionQuit.triggered.connect(self.close)

    def closeEvent(self, event):
        print(event)
        result = QtWidgets.QMessageBox.question(self,
                      "Confirm Exit...",
                      "Are you sure you want to exit ?",
                      QtWidgets.QMessageBox.Yes| QtWidgets.QMessageBox.No)
        event.ignore()
        print(result)
        if result == QtWidgets.QMessageBox.Yes:
            event.accept()

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

回答2:

By connecting the action to the function like that, self.actionQuit.triggered.connect(MainWindow.closeEvent)

you ensure that the triggered signal is passed to the function, but this signal is a boolean as written in the documentation, which means event is a boolean in your code below:

def closeEvent(self, event):
    print(event)
    result = QtWidgets.QMessageBox.question(self,
                  "Confirm Exit...",
                  "Are you sure you want to exit ?",
                  QtWidgets.QMessageBox.Yes| QtWidgets.QMessageBox.No)
    event.ignore()
    print(result)
    if result == QtWidgets.QMessageBox.Yes:
        event.accept()

A boolean does not have an ignore or accept attribute, hence the AttributeError. I do not have a solution but that's the source of your problem. Hopefully exiting the program with a keyboard shortcut is a question that was answered already.