Login dialog PyQt

Question

I nearly finished my application, when the customer asked if I could implement some kind of login form on application startup.

So far I have designed the UI, and tin

Answer 1

A QDialog has its own event loop, so it can be run separately from the main application.

So you just need to check the dialog's return code to decide whether the main application should be run or not.

Example code (PyQt4):

from PyQt4 import QtGui
# from mainwindow import Ui_MainWindow

class Login(QtGui.QDialog):
    def __init__(self, parent=None):
        super(Login, self).__init__(parent)
        self.textName = QtGui.QLineEdit(self)
        self.textPass = QtGui.QLineEdit(self)
        self.buttonLogin = QtGui.QPushButton('Login', self)
        self.buttonLogin.clicked.connect(self.handleLogin)
        layout = QtGui.QVBoxLayout(self)
        layout.addWidget(self.textName)
        layout.addWidget(self.textPass)
        layout.addWidget(self.buttonLogin)

    def handleLogin(self):
        if (self.textName.text() == 'foo' and
            self.textPass.text() == 'bar'):
            self.accept()
        else:
            QtGui.QMessageBox.warning(
                self, 'Error', 'Bad user or password')

class Window(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)
        # self.ui = Ui_MainWindow()
        # self.ui.setupUi(self)    

if __name__ == '__main__':

    import sys
    app = QtGui.QApplication(sys.argv)
    login = Login()

    if login.exec_() == QtGui.QDialog.Accepted:
        window = Window()
        window.show()
        sys.exit(app.exec_())

Example code (PyQt5):

from PyQt5 import QtWidgets
# from mainwindow import Ui_MainWindow

class Login(QtWidgets.QDialog):
    def __init__(self, parent=None):
        super(Login, self).__init__(parent)
        self.textName = QtWidgets.QLineEdit(self)
        self.textPass = QtWidgets.QLineEdit(self)
        self.buttonLogin = QtWidgets.QPushButton('Login', self)
        self.buttonLogin.clicked.connect(self.handleLogin)
        layout = QtWidgets.QVBoxLayout(self)
        layout.addWidget(self.textName)
        layout.addWidget(self.textPass)
        layout.addWidget(self.buttonLogin)

    def handleLogin(self):
        if (self.textName.text() == 'foo' and
            self.textPass.text() == 'bar'):
            self.accept()
        else:
            QtWidgets.QMessageBox.warning(
                self, 'Error', 'Bad user or password')

class Window(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(Window, self).__init__(parent)
        # self.ui = Ui_MainWindow()
        # self.ui.setupUi(self)

if __name__ == '__main__':

    import sys
    app = QtWidgets.QApplication(sys.argv)
    login = Login()

    if login.exec_() == QtWidgets.QDialog.Accepted:
        window = Window()
        window.show()
        sys.exit(app.exec_())