PyQt QSpinBox

Summary: in this tutorial, you’ll learn how to use the PyQt QSpinBox widget to create a spin box.

Introduction to the PyQt QSpinBox widget

A spin box combines a text entry and an up-down control. The up-down control allows you to spin through a set of incremental values:

The values of a spin box can be integers or discrete sets of values e.g., days of weeks and months of years.

A spin box allows you to increase or decrease a value by clicking the up/down buttons or pressing the up/down key on the keyboard. Also, you can type a value manually in the spin box.

To create a spin box, you use the QSpintBox class:

QSpinBox()Code language: Python (python)

Whenever the value of a spin box changes, it emits the valueChanged() signal that sends the current value as an integer.

In addition, the QSpinBox emits the textChanged signal that provides a spin box’s value as an instance of the QString.

The following table lists some useful properties of the QSpinBox:

Let’s take an example of using the PyQt QSpinBox class.

PyQt QSpinBox example

The following program displays a spin box that allows you to enter an amount between one and 100:

import sys
from PyQt6.QtWidgets import QApplication, QWidget, QSpinBox, QLabel, QFormLayout
from PyQt6.QtCore import Qt


class MainWindow(QWidget):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.setWindowTitle('PyQt QSpinBox')
        self.setMinimumWidth(300)

        # create a grid layout
        layout = QFormLayout()
        self.setLayout(layout)

        amount = QSpinBox(minimum=1, maximum=100, value=20, prefix='$')

        amount.valueChanged.connect(self.update)

        self.result_label = QLabel('', self)

        layout.addRow('Amount:', amount)
        layout.addRow(self.result_label)

        # show the window
        self.show()

    def update(self, value):
        self.result_label.setText(f'Current Value: {value}')


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    sys.exit(app.exec())Code language: Python (python)

How it works.

First, create a QSpinBox object with the minimum, maximum, value, and prefix options:

amount = QSpinBox(minimum=1, maximum=100, value=20, prefix='$')Code language: Python (python)

Second, connect the valueChanged signal to the update() method:

 amount.valueChanged.connect(self.update)Code language: Python (python)

Third, create a QLabel for displaying the current value of the spin box:

 self.result_label = QLabel('', self)Code language: Python (python)

Finally, define the update() method that changes the value of the result label whenever the value of the spin box changes:

def update(self, value):
    self.result_label.setText(f'Current Value: {value}')Code language: Python (python)

Summary

• Use QSpinBox class to create a spin box.
• Connect to the valueChanged signal to trigger an action when the current value of a spin box changes