Creating a dialog box in PyQt

Last update on April 25 2025 12:52:07 (UTC/GMT +8 hours)

Write a Python program that creates a simple dialog box that displays a message or input form when a button is clicked using PyQt.

From doc.qt.io:

QApplication Class: The QApplication class manages the GUI application's control flow and main settings.

QMainWindow Class: The QMainWindow class provides a main application window.

QPushButton: The push button, or command button, is perhaps the most commonly used widget in any graphical user interface. Push (click) a button to command the computer to perform some action, or to answer a question. Typical buttons are OK, Apply, Cancel, Close, Yes, No and Help.

QDialog Class: The QDialog class is the base class of dialog windows.

QVBoxLayout Class: This class is used to construct vertical box layout objects.

QLabel Class: The QLabel widget provides a text or image display.

QWidget: The QWidget class is the base class of all user interface objects.

Sample Solution:

Python Code:

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QDialog, QVBoxLayout, QLabel, QWidget

class MyWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        # Set the window properties (title and initial size)
        self.setWindowTitle("Dialog Box Example")
        self.setGeometry(100, 100, 400, 200)  # (x, y, width, height)

        # Create a central widget for the main window
        central_widget = QWidget()
        self.setCentralWidget(central_widget)

        # Create a button that triggers the dialog
        dialog_button = QPushButton("Show Dialog")
        dialog_button.clicked.connect(self.show_dialog)

        # Create a layout for the central widget
        layout = QVBoxLayout()
        layout.addWidget(dialog_button)
        central_widget.setLayout(layout)

    def show_dialog(self):
        # Create a QDialog instance
        dialog = QDialog(self)
        dialog.setWindowTitle("Dialog Box")

        # Create a label with a message
        label = QLabel("This is a message in the dialog box.")

        # Create a layout for the dialog
        dialog_layout = QVBoxLayout()
        dialog_layout.addWidget(label)

        # Set the layout for the dialog
        dialog.setLayout(dialog_layout)

        # Show the dialog as a modal dialog (blocks the main window)
        dialog.exec_()

def main():
    app = QApplication(sys.argv)
    window = MyWindow()
    window.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

Explanation:

In the exercise above -

Import the necessary modules.
Create a "QMainWindow" (MyWindow) with a central widget.
Inside the central widget, we create a 'QPushButton' (dialog_button) labeled "Show Dialog" and connect its clicked signal to the show_dialog method.
In the "show_dialog()" method, we create a QDialog instance (dialog) and set its title.
Create a "QLabel" (label) with the message we want to display in the dialog.
Create a QVBoxLayout for the dialog and add the label to it.
Set the dialog layout using "dialog.setLayout".
When the "Show Dialog" button is clicked, the show_dialog method is called, which displays the dialog as a modal dialog using “dialog.exec_()”. To interact with the main window again, the dialog must be closed.

Output:

Flowchart:

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