Creating Signals in PyQT (BackEnd) | Tutorial for PyQT Desktop App

In this tutorial, we will learn how to create signals in PyQT in the backend of a desktop application. Signals are used to communicate between different parts of the application, such as between different classes or modules.

To get started, make sure you have PyQT installed in your Python environment. If you don’t have it installed, you can do so using the following command:

pip install PyQt5

Now let’s create a simple PyQT application and demonstrate how to create signals. First, create a new Python file and name it backend.py. In this file, we will define a custom class that will emit signals.

from PyQt5.QtCore import QObject, pyqtSignal

class Backend(QObject):
    custom_signal = pyqtSignal()

    def emit_signal(self):
        self.custom_signal.emit()

In the code above, we define a custom class Backend that inherits from QObject, which is a base class for all PyQT objects. We also define a signal called custom_signal using the pyqtSignal decorator. This signal will be emitted whenever the emit_signal method is called.

Next, let’s create the main file for our desktop application. Create a new Python file and name it main.py. In this file, we will create a simple PyQT application with a button that will emit the signal when clicked.

import sys
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QPushButton
from backend import Backend

class MainApp(QWidget):
    def __init__(self):
        super().__init__()

        self.backend = Backend()

        layout = QVBoxLayout()
        self.setLayout(layout)

        button = QPushButton("Click me")
        button.clicked.connect(self.backend.emit_signal)
        layout.addWidget(button)

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

In the code above, we create a MainApp class that inherits from QWidget and contains a button that will emit the signal when clicked. We also create an instance of the Backend class and connect the clicked signal of the button to the emit_signal method of the Backend instance.

To run the application, simply execute the main.py file. When you click the button, the signal will be emitted and you can add more functionality to handle the signal in your backend class.

That’s it! You have successfully created signals in PyQT in the backend of a desktop application. You can now use signals to communicate between different parts of your application and add more complexity to your PyQT projects.