Going back from new window to main window

Question

I have 2 windows, MainScreen and AddFW. Whenever I go from MainScreen -> AddFW, it works (the MainScreen hides and the AddFW appears). But when I try going back from AddFW to MainScreen, the window crashes and I get an error: "NameError: name 'AddFW' is not defined".

What am I doing wrong?

MainScreen.py

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QLineEdit, QPushButton
from PyQt5 import *
from PyQt5 import QtGui
from AddFW import *
import pyodbc

server = '**'
database = '**'
username = '**'
password = '**'
conn = pyodbc.connect('DRIVER={**};'
                      'SERVER=' + server + ';'
                                           'DATABASE=' + database + ';'
                                                                    'UID=' + username + ';'
                                                                                        'PWD=' + password)


class Ui_MainWindow(object):
    def OpenAddFW(self):
        self.window = QtWidgets.QMainWindow()
        self.ui = Ui_AddFW()
        self.ui.setupUi(self.window)
        self.window.show()
        MainWindow.hide()

    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(1000, 600)
        palette = QtGui.QPalette()
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 127))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Active, QtGui.QPalette.Text, brush)
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 127))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Inactive, QtGui.QPalette.Text, brush)
        brush = QtGui.QBrush(QtGui.QColor(120, 120, 120))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Disabled, QtGui.QPalette.Text, brush)
        MainWindow.setPalette(palette)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.label = QtWidgets.QLabel(self.centralwidget)
        self.label.setGeometry(QtCore.QRect(410, 40, 201, 41))
        font = QtGui.QFont()
        font.setFamily("Imprint MT Shadow")
        font.setPointSize(27)
        font.setBold(False)
        font.setUnderline(True)
        font.setWeight(50)
        self.label.setFont(font)
        self.label.setObjectName("label")
        self.InsertResultsBtn = QtWidgets.QPushButton(self.centralwidget)
        self.InsertResultsBtn.setGeometry(QtCore.QRect(58, 226, 160, 130))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.InsertResultsBtn.setFont(font)
        self.InsertResultsBtn.setObjectName("InsertResultsBtn")
        self.SearchResultsBtn = QtWidgets.QPushButton(self.centralwidget)
        self.SearchResultsBtn.setGeometry(QtCore.QRect(300, 226, 160, 130))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.SearchResultsBtn.setFont(font)
        self.SearchResultsBtn.setObjectName("SearchResultsBtn")
        self.CompareResultsBtn = QtWidgets.QPushButton(self.centralwidget)
        self.CompareResultsBtn.setGeometry(QtCore.QRect(541, 226, 160, 130))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.CompareResultsBtn.setFont(font)
        self.CompareResultsBtn.setObjectName("CompareResultsBtn")
        self.AddFWBtn = QtWidgets.QPushButton(self.centralwidget)
        self.AddFWBtn.setGeometry(QtCore.QRect(783, 226, 160, 130))
        font = QtGui.QFont()
        font.setPointSize(11)
        font.setBold(True)
        font.setWeight(75)
        self.AddFWBtn.setFont(font)
        self.AddFWBtn.setObjectName("AddFWBtn")
        self.label_2 = QtWidgets.QLabel(self.centralwidget)
        self.label_2.setEnabled(True)
        self.label_2.setGeometry(QtCore.QRect(420, 540, 181, 16))
        palette = QtGui.QPalette()
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 127))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Active, QtGui.QPalette.Text, brush)
        brush = QtGui.QBrush(QtGui.QColor(255, 0, 127))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Inactive, QtGui.QPalette.Text, brush)
        brush = QtGui.QBrush(QtGui.QColor(120, 120, 120))
        brush.setStyle(QtCore.Qt.SolidPattern)
        palette.setBrush(QtGui.QPalette.Disabled, QtGui.QPalette.Text, brush)
        self.label_2.setPalette(palette)
        self.label_2.setObjectName("label_2")
        MainWindow.setCentralWidget(self.centralwidget)
        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.label.setText(_translate("MainWindow", "TestTrack"))
        self.InsertResultsBtn.setText(_translate("MainWindow", "Insert Results"))
        self.SearchResultsBtn.setText(_translate("MainWindow", "Search Results"))
        self.CompareResultsBtn.setText(_translate("MainWindow", "Compare Results"))
        self.AddFWBtn.setText(_translate("MainWindow", "Add Firmware"))
        self.label_2.setText(_translate("MainWindow", "George Hanna & Nadav Benun"))
        self.AddFWBtn.clicked.connect(self.OpenAddFW)


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_())

AddFW

from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QLineEdit
from PyQt5 import *
from PyQt5 import QtGui
from MainScreen import *
import pyodbc

server = '**'
database = '**'
username = '**'
password = '**'
conn = pyodbc.connect('DRIVER={**};'
                      'SERVER=' + server + ';'
                                           'DATABASE=' + database + ';'
                                                                    'UID=' + username + ';'
                                                                                        'PWD=' + password)


def create(conn2, AddToDataBase):
    cursor = conn2.cursor()
    cursor.execute('insert into dbo.Firmware(Firmware) values(?);', AddToDataBase)
    conn2.commit()
    print('Added!')

class Ui_AddFW(object):
    def AddFWFunc(self):
        create(conn, self.FirmwareInsert.text())

    def BackToMain(self):
        self.window = QtWidgets.QMainWindow()
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self.window)
        self.window.show()
        AddFW.hide()

    def setupUi(self, AddFW):
        AddFW.setObjectName("AddFW")
        AddFW.resize(1000, 600)
        self.centralwidget = QtWidgets.QWidget(AddFW)
        self.centralwidget.setObjectName("centralwidget")
        self.AddFWButton = QtWidgets.QPushButton(self.centralwidget)
        self.AddFWButton.setGeometry(QtCore.QRect(470, 260, 121, 28))
        self.AddFWButton.setObjectName("AddFWButton")
        self.Back = QtWidgets.QPushButton(self.centralwidget)
        self.Back.setGeometry(QtCore.QRect(40, 40, 51, 28))
        self.Back.setObjectName("Back")
        self.FirmwareLabel = QtWidgets.QLabel(self.centralwidget)
        self.FirmwareLabel.setGeometry(QtCore.QRect(320, 170, 60, 16))
        self.FirmwareLabel.setObjectName("FirmwareLabel")
        self.Title = QtWidgets.QLabel(self.centralwidget)
        self.Title.setGeometry(QtCore.QRect(370, 50, 321, 16))
        font = QtGui.QFont()
        font.setPointSize(12)
        font.setBold(True)
        font.setWeight(75)
        self.Title.setFont(font)
        self.Title.setObjectName("Title")
        self.FirmwareInsert = QtWidgets.QLineEdit(self.centralwidget)
        self.FirmwareInsert.setGeometry(QtCore.QRect(400, 160, 281, 31))
        sizePolicy = QtWidgets.QSizePolicy(QtWidgets.QSizePolicy.Expanding, QtWidgets.QSizePolicy.Fixed)
        sizePolicy.setHorizontalStretch(0)
        sizePolicy.setVerticalStretch(0)
        sizePolicy.setHeightForWidth(self.FirmwareInsert.sizePolicy().hasHeightForWidth())
        self.FirmwareInsert.setSizePolicy(sizePolicy)
        self.FirmwareInsert.setObjectName("FirmwareInsert")
        AddFW.setCentralWidget(self.centralwidget)
        self.statusbar = QtWidgets.QStatusBar(AddFW)
        self.statusbar.setObjectName("statusbar")
        AddFW.setStatusBar(self.statusbar)
        self.retranslateUi(AddFW)
        QtCore.QMetaObject.connectSlotsByName(AddFW)

    def retranslateUi(self, AddFW):
        _translate = QtCore.QCoreApplication.translate
        AddFW.setWindowTitle(_translate("AddFW", "MainWindow"))
        self.AddFWButton.setText(_translate("AddFW", "Insert to DataBase"))
        self.Back.setText(_translate("AddFW", "Back"))
        self.FirmwareLabel.setText(_translate("AddFW", "Firmware:"))
        self.Title.setText(_translate("AddFW", "Add Firmware to the DataBase"))
        self.AddFWButton.clicked.connect(self.AddFWFunc)
        self.Back.clicked.connect(self.BackToMain)


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

score 0 · Answer 1 · answered Jul 30 '20 at 14:21

This happens because Add_FW exists only within the setupUi and retranslateUi methods. It works in MainWindow because you are declaring it below in

if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow() <- HERE
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

One quick fix is to pass the AddFW object through connect this way :

self.Back.clicked.connect(lambda: self.BackToMain(AddFW))

But a better way to deal with this would be to inherit QMainWindow in both Ui_AddFW and Ui_MainWindow class due to which they both become an instance of QMainWindow and you wont have to pass the QMainWindow when you are instantiating it. Check this out: PyQt class inheritance

Finally,

Instead of showing and hiding screens within each object, I would suggest creating a main.py and handle the show/hide logic there this way:

main.py

from AddFW import Ui_AddFW
from MainScreen import Ui_MainWindow


def handle_back_to_main():
    add_fw.hide()
    main_screen.show()

def handle_back_to_add_fw():
    main_screen.hide()
    add_fw.show()

add_fw =  Ui_AddFW()
main_screen = Ui_MainWindow()
add_fw.Back.clicked.connect(handle_back_to_main)
main_screen.AddFWBtn.clicked.connect(handle_back_to_add_fw)

I tried the self.Back.clicked.connect(lambda: self.BackToMain(AddFW)) solution, but it didn't work, I get an error: TypeError: reduce expected at least 2 arguments, got 1 — HG9, Jul 31 '20 at 13:26
The problem is that I almost know nothing about Python, I'm just watching tutorials to help me make a project for work. I need help :) — HG9, Jul 31 '20 at 13:26

Going back from new window to main window

1 Answers1