How to assign a value to a variable from a splitbox?

Question

I created an elementary template in Qt designer with two windows (Qspinbox) and one button (QPushButton). The idea is this. The user enters numbers in both fields, presses the button and the program performs certain actions with these numbers. (For example, it adds up). I understand that you need to create a function that will specify what needs to be done with the numbers entered by the user. Bind the "button click" event to this function. (I can link a button click to a function.) But here's how I assign the values entered by the user to the variables for further work with them (with variables). PLEASE help, I'm fighting for the second week! Here is the source code:

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(507, 294)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(270, 200, 75, 23))
        self.pushButton.setObjectName("pushButton")
        self.layoutWidget = QtWidgets.QWidget(self.centralwidget)
        self.layoutWidget.setGeometry(QtCore.QRect(90, 100, 291, 22))
        self.layoutWidget.setObjectName("layoutWidget")
        self.horizontalLayout_2 = QtWidgets.QHBoxLayout(self.layoutWidget)
        self.horizontalLayout_2.setContentsMargins(0, 0, 0, 0)
        self.horizontalLayout_2.setObjectName("horizontalLayout_2")
        self.label_2 = QtWidgets.QLabel(self.layoutWidget)
        self.label_2.setObjectName("label_2")
        self.horizontalLayout_2.addWidget(self.label_2)
        self.spinBox_2 = QtWidgets.QSpinBox(self.layoutWidget)
        self.spinBox_2.setObjectName("spinBox_2")
        self.horizontalLayout_2.addWidget(self.spinBox_2)
        self.widget = QtWidgets.QWidget(self.centralwidget)
        self.widget.setGeometry(QtCore.QRect(90, 30, 291, 22))
        self.widget.setObjectName("widget")
        self.horizontalLayout = QtWidgets.QHBoxLayout(self.widget)
        self.horizontalLayout.setContentsMargins(0, 0, 0, 0)
        self.horizontalLayout.setObjectName("horizontalLayout")
        self.label = QtWidgets.QLabel(self.widget)
        self.label.setObjectName("label")
        self.horizontalLayout.addWidget(self.label)
        self.spinBox = QtWidgets.QSpinBox(self.widget)
        self.spinBox.setObjectName("spinBox")
        self.horizontalLayout.addWidget(self.spinBox)
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 507, 21))
        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", "calculate"))
        self.label_2.setText(_translate("MainWindow", "Input second number:"))
        self.label.setText(_translate("MainWindow", "Input first number:"))


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

And here's what I added to implement the goal. What am I doing wrong?

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(507, 294)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.pushButton = QtWidgets.QPushButton(self.centralwidget)
        self.pushButton.setGeometry(QtCore.QRect(270, 200, 75, 23))
        self.pushButton.setObjectName("pushButton")
        self.layoutWidget = QtWidgets.QWidget(self.centralwidget)
        self.layoutWidget.setGeometry(QtCore.QRect(90, 100, 291, 22))
        self.layoutWidget.setObjectName("layoutWidget")
        self.horizontalLayout_2 = QtWidgets.QHBoxLayout(self.layoutWidget)
        self.horizontalLayout_2.setContentsMargins(0, 0, 0, 0)
        self.horizontalLayout_2.setObjectName("horizontalLayout_2")
        self.label_2 = QtWidgets.QLabel(self.layoutWidget)
        self.label_2.setObjectName("label_2")
        self.horizontalLayout_2.addWidget(self.label_2)
        self.spinBox_2 = QtWidgets.QSpinBox(self.layoutWidget)
        self.spinBox_2.setObjectName("spinBox_2")
        self.horizontalLayout_2.addWidget(self.spinBox_2)
        self.widget = QtWidgets.QWidget(self.centralwidget)
        self.widget.setGeometry(QtCore.QRect(90, 30, 291, 22))
        self.widget.setObjectName("widget")
        self.horizontalLayout = QtWidgets.QHBoxLayout(self.widget)
        self.horizontalLayout.setContentsMargins(0, 0, 0, 0)
        self.horizontalLayout.setObjectName("horizontalLayout")
        self.label = QtWidgets.QLabel(self.widget)
        self.label.setObjectName("label")
        self.horizontalLayout.addWidget(self.label)
        self.spinBox = QtWidgets.QSpinBox(self.widget)
        self.spinBox.setObjectName("spinBox")
        self.horizontalLayout.addWidget(self.spinBox)
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 507, 21))
        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", "calculate"))
        self.label_2.setText(_translate("MainWindow", "Input second number:"))
        self.label.setText(_translate("MainWindow", "Input first number:"))

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()

    def calc(self):
        first_n = self.label_2.value()
        second_n = self.label.value()

        result = first_n + second_n
        print(result)
ui.pushButton.clicked.connect(calc)


sys.exit(app.exec_())

I believe that the calc method would be better written above "if __name__ == "__main__":" 5:41 but then there is a trace error: NameError: name 'calc' is not defined

Answer 1

In Python, the name self is used to mention the current object. In your code, you should define calc inside the class Ui_mainwindow, which makes calc a method of Ui_mainwindow, instead of outside the Class.