How to reboot PyQt5 application

Question

I'm trying to restart my application after an update from the client side. I was able to achieve till the auto update part. I tried to surf on How to restart PyQt application?. There are few similar questions earlier, but none of them have good explanation or example with a button click event. Could you guys help me understand on how to reboot a PyQt application. Basically I want to restart the application from if __name__ == '__main__': everytime there is an update.

Note: AppLogin is my private module I created to handle application login. So basically that would be the landing QDialog once application is opened.

from PyQt5.QtWidgets import *
import sys
import AppLogin

class App:
    def __init__(self):
        btn = QPushButton(main_window)
        btn.setText('close')
        btn.pressed.connect(self.restart)
        main_window.show()

    def restart(self):
        # Here goes the code for restart
        pass


if __name__ == '__main__':
    appctxt = QApplication(sys.argv)
    log_in = AppLogin.Login()
    if log_in.exec_() == QDialog.Accepted:
        main_window = QMainWindow()
        ui = App()
        exit_code = appctxt.exec_()
        sys.exit(exit_code)

score 6 · Accepted Answer · answered Jun 27 '20 at 14:08

6

The logic is to end the eventloop and launch the application an instant before it closes:

import sys
from PyQt5 import QtCore, QtWidgets


def restart():
    QtCore.QCoreApplication.quit()
    status = QtCore.QProcess.startDetached(sys.executable, sys.argv)
    print(status)


def main():
    app = QtWidgets.QApplication(sys.argv)

    print("[PID]:", QtCore.QCoreApplication.applicationPid())

    window = QtWidgets.QMainWindow()
    window.show()

    button = QtWidgets.QPushButton("Restart")
    button.clicked.connect(restart)

    window.setCentralWidget(button)

    sys.exit(app.exec_())


if __name__ == "__main__":
    main()

answered Jun 27 '20 at 14:08

eyllanesc

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Thank you very much for acknowledging, I tried the code sample. It is only stopping the application, the application is not restarting. fyi - I'm on Windows – testuserme Jun 27 '20 at 14:36
@testuserme How do you run your application? Do you use some IDE? try launching the script from the console – eyllanesc Jun 27 '20 at 16:15

score 2 · Answer 2 · answered May 12 '21 at 21:53

A solution is to close (or forget) the QMainWindow and recreate it.

If you just "show()" a single widget, the same idea works fine.

import sys
import uuid

from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton


class MainWindow(QMainWindow):
    singleton: 'MainWindow' = None

    def __init__(self):
        super().__init__()
        btn = QPushButton(f'RESTART\n{uuid.uuid4()}')
        btn.clicked.connect(MainWindow.restart)
        self.setCentralWidget(btn)
        self.show()

    @staticmethod
    def restart():
        MainWindow.singleton = MainWindow()


def main():
    app = QApplication([])
    MainWindow.restart()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

How to reboot PyQt5 application

2 Answers2

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