Errors while reading data in PyQT from excel file: GtkDialog mapped without a transient parent. This is discouraged

Question

I try to read dataframe from excel file and print it after button click.

import sys
from PyQt5 import QtCore, QtGui, QtWidgets
from PyQt5.QtWidgets import QApplication, QWidget, QPushButton, QMessageBox
from PyQt5.QtGui import QIcon
from excel_reading import *


class MyWin(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self):
        super().__init__()
        self.setupUi(self)
        self.pushButton.clicked.connect(self.hello)

    def hello(self):
        data_input_from_file = QtWidgets.QFileDialog.getOpenFileName(self,'header','filename','Excel (*.xlsx *.xls)')
        print(data_input_from_file)



if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    myapp = MyWin()
    myapp.show()
    sys.exit(app.exec_())

When I click button, I have such message:

Gtk-Message: 00:03:53.573: GtkDialog mapped without a transient parent. This is discouraged.
('', '')

How should I solve that problem?

I solved the problem: 
    def hello(self):
        data_input_from_file = QtWidgets.QFileDialog.getOpenFileName(self, 'header', 'filename', 'Excel (*.xlsx *.xls)')
        print(type(data_input_from_file))
        print(data_input_from_file)
        print(pd.read_excel(data_input_from_file[0]))

Answer 1

The Gtk warning is just what it is: a warning. You can ignore that. Qt tries to use the system native file dialogs whenever possible, which might result in some warnings in the consolle output.

Your issue is related to something else: there are rare cases for which PyQt functions don't return the same signature as reported in the official Qt (C++) documentation.

QFileDialog static methods is one of such cases, as QFileDialog.getOpenFileName() always returns a tuple: the selected file path and the selected file type filter. This is also clear from the output of your code (which I suppose is caused by cancelling the dialog):

('', '')

The first value is the selected file (in this case, none) and filter (again, none, as there was no selected file).

The solution is to assign two values for what the static returns:

    filePath, filters = QtWidgets.QFileDialog.getOpenFileName(
        self,'header','filename','Excel (*.xlsx *.xls)')
    if filePath:
        # do something