QtGui.QFileDialog.getExistingDirectory() window won't close after directory has been chosen (PyQt)

Question

I am trying to get a path with the QtGui.QFileDialog.getExistingDirectory() dialog window in a python program to ease things up for users while the rest of the program is in console output. I have this piece of code for this purpose:

import sys, os
from PyQt4 import QtGui

def getpath(filename,
            noPathFileMsg='',
            wrongFolderMsg='',
            selectFolderMsg=''):

    try:
        f = open('./'+filename,'r')
    except IOError:
        folder = get_new_path(filename,
                                     noPathFileMsg, 
                                     selectFolderMsg)
    else:
        folder = f.readline()
        f.close()
        currentDir = os.getcwd()
        try:
            os.chdir(folder)
        except:
            folder = get_new_path(filename,
                                         wrongFolderMsg,
                                         selectFolderMsg)
        else:
            os.chdir(currentDir)
    finally:
        return folder

def get_new_path(filename,
                 infoMsg,
                 selectFolderMsg):

    app = QtGui.QApplication(sys.argv)
    QtGui.QMessageBox.about(None, 'No folder', infoMsg)
    folder = QtGui.QFileDialog.getExistingDirectory(None, selectFolderMsg)
    app.exit()
    if os.name == 'posix':
        folder += '/'
    elif os.name == 'nt':
        folder += '\\'
    g = open('./'+filename,'w')
    g.write(folder)
    g.close()
    return folder
if __name__ == '__main__':
    folderPath = getpath('pathtofolder.txt',
                         noPathFileMsg='The path to the folder has not been set',
                         wrongFolderMsg='The path folder saved cannot be reached',
                         selectFolderMsg='Please select a folder')
    print folderPath
    var = input('The program stopped at the input instruction, the dialog window should now be closed!')

If I call the getpath function the dialog window stays open until the script that called the function ends instead of closing just after this instruction:

folder = QtGui.QFileDialog.getExistingDirectory(None, selectFolderMsg)

If you run this code it will create a file that saves the directory saved with the dialog window in the folder where the script is run.

What did I do wrong?

By the way, I am on Ubuntu 12.04. Thank you! Cheers

Answer 1

After setting up Ubuntu 12.04 in a VM, I can confirm that the dialog doesn't close properly after clicking "Open".

The problem seems to be caused by attempting to quit the QApplication inside the get_new_path function.

Instead, you should create a single, global QApplication object, and only quit it when the script completes:

def get_new_path(filename, infoMsg, selectFolderMsg):

    QtGui.QMessageBox.about(None, 'No folder', infoMsg)
    folder = QtGui.QFileDialog.getExistingDirectory(None, selectFolderMsg)
    ...

if __name__ == '__main__':

    app = QtGui.QApplication(sys.argv)

    folderPath = getpath(...)

    app.exit()