I'm getting error in pyqt5, while connecting push button

Question

I'm first time using pyqt5. After creating the UI from QT designer, and then converting the UI file to python file, I'm getting error, the strange part is sometimes when i try to recreate the UI from Designer i don't get the error, but sometimes with same code line by line, I get this error. Maybe I'm doing something wrong in the qt designer, I don't know what is wrong.

QObject::connect: Cannot connect QPushButton::clicked(bool) to (null)::browse_slot()

TypeError: connect() failed between clicked(bool) and browse_slot()

MY CODE :

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QMainWindow

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(640, 480)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(280, 200, 89, 25))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 640, 22))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)
        self.retranslateUi(MainWindow)
        self.pushButton.clicked.connect(self.browse_slot)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "PushButton"))

    @QtCore.pyqtSlot( )
    def browse_slot( self ):
        options = QtWidgets.QFileDialog.Options()
        options |= QtWidgets.QFileDialog.DontUseNativeDialog
        fileName, _ = QtWidgets.QFileDialog.getOpenFileName(
                        None,
                        "QFileDialog.getOpenFileName()",
                        "",
                        "All Files (*);;Python Files (*.py)",
                        options=options)
        if fileName:
            self.debugPrint( "setting file name: " + fileName )
            self.model.setFileName( fileName )
            self.refreshAll()

if __name__ == "__main__":
    import sys
    app = QApplication(sys.argv)
    Window = QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(Window)
    Window.show()
    sys.exit(app.exec_())

score 5 · Accepted Answer · answered Nov 28 '18 at 13:17

If you want to make the connection using @QtCore.pyqtSlot() you must use it in a class that inherits from QObject, on the other hand the PyQt docs indicate that it is recommended that you create a class that inherits from the appropriate widget, in this case QMainWindow and that you use the class as an interface, this also solves the first point because QMainWindow inherits from QObject.

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(640, 480)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(280, 200, 89, 25))
        self.pushButton.setObjectName("pushButton")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 640, 22))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)
        self.retranslateUi(MainWindow)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.pushButton.setText(_translate("MainWindow", "PushButton"))

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)
        self.pushButton.clicked.connect(self.browse_slot)

    @QtCore.pyqtSlot()
    def browse_slot(self):
        options = QtWidgets.QFileDialog.Options()
        options |= QtWidgets.QFileDialog.DontUseNativeDialog
        fileName, _ = QtWidgets.QFileDialog.getOpenFileName(
                        None,
                        "QFileDialog.getOpenFileName()",
                        "",
                        "All Files (*);;Python Files (*.py)",
                        options=options)
        if fileName:
            self.debugPrint( "setting file name: " + fileName )
            self.model.setFileName( fileName )
            self.refreshAll()

if __name__ == "__main__":
    import sys
    app =QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())

score 0 · Answer 2 · edited Sep 04 '19 at 06:33

0

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):

change to

class Ui_MainWindow(Qobject):
    def setupUi(self, MainWindow):

edited Sep 04 '19 at 06:33

adiga

34,372
9
61
83

answered Sep 04 '19 at 06:22

nalayak

27
1
7

I'm getting error in pyqt5, while connecting push button

2 Answers2