PyQt5 QSpinBox – Blocking Signals

In this article we will see how we can block the signals of the spin box, blocking signals means the connected methods with the spin box will not receive the signals for example when we add action to it when its value changes that action will not work. Signals emitted while being blocked are not buffered.

Note : The destroyed() signal will be emitted even if the signals for the spin box have been blocked

In order to do this we use blockSignals method.

Syntax : spin_box.blockSignals(True)

Argument : It takes bool as argument

Action Performed : It blocks the emitting signals of spin box

Below is the implementation

# importing libraries
from PyQt5.QtWidgets import *
from PyQt5 import QtCore, QtGui
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import sys


class Window(QMainWindow):

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

        # setting title
        self.setWindowTitle("Python ")

        # setting geometry
        self.setGeometry(100, 100, 600, 400)

        # calling method
        self.UiComponents()

        # showing all the widgets
        self.show()

    # method for widgets
    def UiComponents(self):
        # creating spin box
        self.spin = QSpinBox(self)

        # setting geometry to spin box
        self.spin.setGeometry(100, 100, 250, 40)

        # setting prefix to spin
        self.spin.setPrefix("Prefix ")

        # setting suffix to spin
        self.spin.setSuffix(" Suffix")

        # adding action to the spin box
        self.spin.valueChanged.connect(self.do)

        # blocking signals of the spin box
        self.spin.blockSignals(True)

        # creating a label
        self.label = QLabel("Label ", self)

        # setting geometry to the label
        self.label.setGeometry(100, 200, 300, 30)

    # method called by spin box
    def do(self):
        # setting text to the label
        self.label.setText("Action done")


# create pyqt5 app
App = QApplication(sys.argv)

# create the instance of our Window
window = Window()

# start the app
sys.exit(App.exec())

Output :
Label text didn’t change as signals of spin box are blocked so they can’t call the value changed signal