Python PyQt5: How to show an error message with PyQt5

Question

In normal Python (3.x) we always use showerror() from the tkinter module to display an error message but what should I do in PyQt5 to display exactly the same message type as well?

Answer 1

import sys
from PyQt5.QtWidgets import QMessageBox
import PyQt5
from PyQt5 import QtWidgets
"""
Stadard button
QMessageBox.Ok
QMessageBox.Open
QMessageBox.Save
QMessageBox.Cancel
QMessageBox.Close
QMessageBox.Yes
QMessageBox.No
QMessageBox.Abort
QMessageBox.Retry
QMessageBox.Ignore
"""

class MessageBox(QMessageBox):
    def __init__(self, parent=None):
        super().__init__(parent)
        
    #showinfo    
    def showinfo(self,title,text):
        self.setWindowTitle(title)
        self.setText(text)
        
        self.setIcon(QMessageBox.Information)
        self.standard_button=QMessageBox.Ok
        self.setStandardButtons(self.standard_button)
        return self.execute()


    #showwarning
    def showwarning(self,title,text):
        self.setWindowTitle(title)
        self.setText(text)
        self.setIcon(QMessageBox.Warning)
        self.standard_button=QMessageBox.Ok
        self.setStandardButtons(self.standard_button)
        return self.execute()


    #showerror
    def showerror(self,title,text):
        
        self.setWindowTitle(title)
        self.setText(text)
        self.setIcon(QMessageBox.Critical)
        self.standard_button=QMessageBox.Ok
        self.setStandardButtons(self.standard_button)
        return self.execute()
       


    #askyesno
    def askyesno(self,title,text):
        self.setWindowTitle(title)
        self.setText(text)
        self.setIcon(QMessageBox.Question)
        self.standard_button=QMessageBox.Yes | QMessageBox.No
        self.setStandardButtons(self.standard_button)
        return self.execute()


    #askyesnocancel
    def askyesnocancel(self,title,text):
        self.setWindowTitle(title)
        self.setText(text)
        self.setIcon(QMessageBox.Question)
        self.standard_button=QMessageBox.Yes | QMessageBox.No| QMessageBox.Cancel
        self.setStandardButtons(self.standard_button)
        return self.execute()

    #asksave
    def asksave(self,title,text):
        self.setWindowTitle(title)
        self.setText(text)
        self.setIcon(QMessageBox.Question)
        self.standard_button=QMessageBox.Save | QMessageBox.No| QMessageBox.Cancel
        self.setStandardButtons(self.standard_button)
        return self.execute()

    #asksave
    def askopen(self,title,text):
        self.setWindowTitle(title)
        self.setText(text)
        self.setIcon(QMessageBox.Question)
        self.standard_button=QMessageBox.Open | QMessageBox.No
        self.setStandardButtons(self.standard_button)
        return self.execute()

    #execute
    def execute(self):
        self.exec_()
        msg_returned=str(self.clickedButton().text()).replace('&','')
        return msg_returned

    
#Test

from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QWidget, QApplication, QListWidget, QVBoxLayout, QLineEdit,QPushButton



class Widget(QWidget):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("Msgbox")
        self.layout=QVBoxLayout()
        self.button=QPushButton("show message box")
        self.layout.addWidget(self.button)
        self.setLayout(self.layout)
        self.button.clicked.connect(self.handle_text_changed)

        #messagebox 
        self.msgbox = MessageBox()

    def handle_text_changed(self):
            #res = self.msgbox.showinfo("Title","This is a text")
            #res = self.msgbox.showerror("Title","This is a text")  #askyesnocancel
            #res = self.msgbox.askyesnocancel("Title","This is a text")
            #res = self.msgbox.askyesno("Title","This is a text")
            #res = self.msgbox.showwarning("Title","This is a text")  
            #res = self.msgbox.showerror("Title","This is a text")  
            #res = self.msgbox.asksave("Title","This is a text")  
            #res = self.msgbox.askopen("Title","This is a text")  
            res = self.msgbox.showinfo("Title","This is a text")  
            print(res)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    mainwindow = Widget()
    mainwindow.show()
    sys.exit(app.exec_())
    
    

`

Answer 2

Assuming you are in a QWidget from which you want to display an error message, you can simply use QMessageBox.critical(self, "Title", "Message"), replace self by another (main widget for example) if you are not is a QWidget class.

---

Edit: even if you are not in a QWidget (or don't want to inherit from it), you can just use None as parent with for instance QMessageBox.critical(None, "Title", "Message").

---

Edit, here is an example of how to use it:

# -*-coding:utf-8 -*

from PyQt5.QtWidgets import QApplication, QMessageBox
import sys

# In this example, success is False by default, and
#  - If you press Cancel, it will ends with False,
#  - If you press Retry until i = 3, it will end with True


expectedVal = 3


def MyFunction(val: int) -> bool:
    return val == expectedVal


app = QApplication(sys.argv)
i = 1
success = MyFunction(i)
while not success:
    # Popup with several buttons, manage below depending on choice
    choice = QMessageBox.critical(None,
                                  "Error",
                                  "i ({}) is not expected val ({})".format(i, expectedVal),
                                  QMessageBox.Retry | QMessageBox.Cancel)
    if choice == QMessageBox.Retry:
        i += 1
        print("Retry with i = {}".format(i))
        success = MyFunction(i)
    else:
        print("Cancel")
        break

if success:
    # Standard popup with only OK button
    QMessageBox.information(None, "Result", "Success is {}".format(success))
else:
    # Standard popup with only OK button
    QMessageBox.critical(None, "Result", "Success is {}".format(success))

Answer 3

Don't forget to call .exec_() to display the error:

from PyQt5.QtWidgets import QMessageBox

msg = QMessageBox()
msg.setIcon(QMessageBox.Critical)
msg.setText("Error")
msg.setInformativeText('More information')
msg.setWindowTitle("Error")
msg.exec_()

Answer 4

To show a message box, you can call this def:

from PyQt5.QtWidgets import QMessageBox, QWidget

MainClass(QWidget):
    def __init__(self):
        super().__init__()

    def clickMethod(self):
        QMessageBox.about(self, "Title", "Message")

Answer 5

All above options didn't work for me using Komodo Edit 11.0. Just had returned "1" or if not implemented "-1073741819".

Usefull for me was: Vanloc's solution.

def my_exception_hook(exctype, value, traceback):
    # Print the error and traceback
    print(exctype, value, traceback)
    # Call the normal Exception hook after
    sys._excepthook(exctype, value, traceback)
    sys.exit(1)

# Back up the reference to the exceptionhook
sys._excepthook = sys.excepthook

# Set the exception hook to our wrapping function
sys.excepthook = my_exception_hook

Answer 6

The following should work:

msg = QMessageBox()
msg.setIcon(QMessageBox.Critical)
msg.setText("Error")
msg.setInformativeText(e)
msg.setWindowTitle("Error")

It is not the exact same message type (different GUI's) but fairly close. e is the expression for an Error in python3

Hope that helped, Narusan

Answer 7

Qt includes an error-message specific dialog class QErrorMessage which you should use to ensure your dialog matches system standards. To show the dialog just create a dialog object, then call .showMessage(). For example:

error_dialog = QtWidgets.QErrorMessage()
error_dialog.showMessage('Oh no!')

Here is a minimal working example script:

import PyQt5
from PyQt5 import QtWidgets

app = QtWidgets.QApplication([])

error_dialog = QtWidgets.QErrorMessage()
error_dialog.showMessage('Oh no!')

app.exec_()