PyQt4 MainWindow object has no attribute

Question

I'm writing some GUI and then I want to add text to a listView. Right now I just want to add "hello" to figure it out, and then I will grow it from there.

Here is a sample of my code:

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_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName(_fromUtf8("MainWindow"))
        MainWindow.resize(584, 461)
        self.centralwidget = QtGui.QWidget(MainWindow)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.lineEdit_6 = QtGui.QLineEdit(self.centralwidget)
        self.lineEdit_6.setGeometry(QtCore.QRect(72, 210, 171, 20))
        ....
        self.retranslateUi(MainWindow)
        QtCore.QObject.connect(self.pushButton, QtCore.SIGNAL(_fromUtf8("clicked()")), MainWindow.addEntry)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        ....

    def addEntry(self):
        listView.Items.Add("Hello")

Then to open it:

from PyQt4 import *
import signal
import sys
from PyQt4.QtGui import QApplication, QMessageBox
from inv_window import *
def main():
    app = QtGui.QApplication(sys.argv)
    MainWindow = QtGui.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

When trying to run this I get:

AttributeError: 'QMainWindow' object has no attribute 'addEntry'

Any ideas on how I can rectify this? I've tried googling but I'm having a difficult time nailing down a solution

Answer 1

The problem appears to be on this line:

        QtCore.QObject.connect(self.pushButton, QtCore.SIGNAL(_fromUtf8("clicked()")), MainWindow.addEntry)

Your MainWindow variable is a QMainWindow instance, and so it doesn't have the addEntry method which belongs to your Ui_MainWindow class. Hence the error you see.

I'd like to point out a stylistic issue with your code, if I may. In Python, names of local variables and method/function parameters conventionally start with a lower-case letter. You have a variable (and method parameter) named MainWindow. When I first read your code I got confused because MainWindow looked to me like the name of a class. I would recommend changing the name of this variable/method parameter to mainWindow or main_window or mainwin or suchlike.