PyQt4：如何从主窗口重新打开对话框窗口

Question

I am using PyQt4 with Python 3. I am trying to open a dialog window when a button in the main window is pressed. The dialog window also needs to be able to send data back to the main window via signals.

A similar question has been asked here: Open a second window in PyQt

I have used that post as a guide to build my code. Now all of that is currently working, except for if you close the dialog window, and try to open it again, you get:

RuntimeError: wrapped C/C++ object of type QDialog has been deleted

Meaning you have to restart the program before you can open it again. This will not work for my particular application.

From what I understand here: https://www.daniweb.com/programming/software-development/threads/299395/pyqt-how-to-open-and-close-dialog-multiple-times

I need to destroy the object (the dialog window) before trying to open it again. I tried to do that, however I am not sure how to do it without closing the entire application when I just want to close the dialog window. Also not sure if that is the solution.

Here is a summarized version of my code:

Main window:

from PyQt4 import QtCore, QtGui
#Qt designer generated code here
class Ui_MainWindow(object):

    def setupUi(self, MainWindow):
        #Ui setup stuff here
        #Button 3
        self.pushButton_3 = QtGui.QPushButton(self.centralwidget)
        self.pushButton_3.clicked.connect(self.pressed_3)

        QtCore.QMetaObject.connectSlotsByName(MainWindow)
        #signal from dialog menu
        self.dialog = QtGui.QDialog()
        self.dialog.ui = entry_window_2.Ui_Dialog()
        self.dialog.ui.setupUi(self.dialog)
        self.dialog.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        self.dialog.ui.sendVals.connect(self.recieved_save_data)

    def pressed_3(self, checked=None):
        self.dialog.exec_()

    def recieved_save_data(self, value):
        print(value)

Dialog window

from PyQt4 import QtCore, QtGui
#PyQt generated code here

class Ui_Dialog(QtCore.QObject):
    sendVals = QtCore.pyqtSignal(int)

    def setupUi(self, Dialog):
        #PyQt Ui_setup code here

        self.ok_cancel = QtGui.QDialogButtonBox(Dialog)
        self.ok_cancel.setStandardButtons(QtGui.QDialogButtonBox.Cancel|QtGui.QDialogButtonBox.Ok)
        self.ok_cancel.accepted.connect(self.save)

        QtCore.QObject.connect(self.ok_cancel, QtCore.SIGNAL(_fromUtf8("accepted()")), Dialog.accept)
        QtCore.QObject.connect(self.ok_cancel, QtCore.SIGNAL(_fromUtf8("rejected()")), Dialog.reject)
        QtCore.QMetaObject.connectSlotsByName(Dialog)

    def save(self):
        self.sendVals.emit(1212)

Any help would be appreciated! :)

Answer 1

So I solved the issue thanks to this article: http://enki-editor.org/2014/08/23/Pyqt_mem_mgmt.html

The solution is to delete this line here:

self.dialog.setAttribute(QtCore.Qt.WA_DeleteOnClose)

I am no expert, but from what I understand, for every C++ class in PyQt there is a python wrapper class. As the python programmer, you are interacting with the python wrapper, and wrapper interacts with the C++ class in the background.

The issue here is the "C++ object is deleted by Qt but Python wrapper still exists". This appears to be caused by that line that just deleted.

Perhaps someone can explain it better than I can. But that did in fact fix the problem.