Pyqt - What signal does my standard "Apply" button emit and how do I write the slot for it?

Question

I'm just learning pyqt and I'm trying to understand Standard buttons. I'm just learning, so let me know if I did something grossly wrong.

I've created a simple UI with some standard buttons in QT Designer.

I noted that the accepted() and rejected() signals are being connected to the accept and reject slots, so I wrote them. The Ok button and cancel button work as expected, but the Apply button simply doesn't react. How do I connect the apply button to a slot?

sample.py - Here's my sample app code:

import sys
from PyQt4 import QtGui

import designer

class SampleApp(QtGui.QWidget):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self,parent)
        self.ui = designer.Ui_Dialog()
        self.ui.setupUi(self)

    def reject(w):
        print("reject", w)
        w.close()

    def accept(w):
        print("accept", w)

if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    myapp = SampleApp()
    myapp.show()
    sys.exit(app.exec_())

designer.py - Here's the auto-generated QT Designer code:

# -*- coding: utf-8 -*-

# Form implementation generated from reading ui file 'designer.ui'
#
# Created by: PyQt4 UI code generator 4.11.4
#
# WARNING! All changes made in this file will be lost!

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName(_fromUtf8("Dialog"))
        Dialog.resize(554, 399)
        self.buttonBox = QtGui.QDialogButtonBox(Dialog)
        self.buttonBox.setGeometry(QtCore.QRect(190, 340, 341, 32))
        self.buttonBox.setOrientation(QtCore.Qt.Horizontal)
        self.buttonBox.setStandardButtons(QtGui.QDialogButtonBox.Apply|QtGui.QDialogButtonBox.Close|QtGui.QDialogButtonBox.Ok)
        self.buttonBox.setCenterButtons(False)
        self.buttonBox.setObjectName(_fromUtf8("buttonBox"))

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

    def retranslateUi(self, Dialog):
        Dialog.setWindowTitle(_translate("Dialog", "Dialog", None))

Answer 1

You'll need to connect the clicked signal from the Apply button manually in your widget.

class SampleApp(QtGui.QWidget):

    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self,parent)
        self.ui = designer.Ui_Dialog()
        self.ui.setupUi(self)
        btn = self.ui.buttonBox.button(QtGui.QDialogButtonBox.Apply)
        btn.clicked.connect(self.accept)