PyQt5 QDateTimeEdit – Only emit signal when time changes

PyQt5 QDateTimeEdit is a widget that displays an editable QDateTime object. By default, it emits a signal whenever the user changes the date or time. However, sometimes we want to only emit the signal when the time changes. In this tutorial, we will learn how to do that.

Setting up the environment

Before we begin, we need to make sure that the PyQt5 library is installed. If you haven’t already, you can install it by running the following command:

pip install PyQt5

We will also need to import the following modules:

from PyQt5.QtWidgets import QApplication, QDateTimeEdit
from PyQt5.QtCore import QDateTime, Qt

Creating a QDateTimeEdit widget

First, we need to create a QDateTimeEdit widget and set its display format. In this example, we will set the display format to show the date and time in long format.

app = QApplication([])
date_edit = QDateTimeEdit()
date_edit.setDisplayFormat("yyyy-MM-dd HH:mm:ss")
date_edit.setMinimumDateTime(QDateTime.currentDateTime())

Defining the custom signal

To emit a signal only when the time changes, we need to define a custom signal. This signal will be emitted only when the time component of the underlying QDateTime object changes.

class TimeEdit(QDateTimeEdit):
    timeChanged = pyqtSignal()

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.last_time = None

    def stepBy(self, steps):
        super().stepBy(steps)
        time = self.time()
        if time != self.last_time:
            self.last_time = time
            self.timeChanged.emit()

Here, we subclass QDateTimeEdit and define a new signal called timeChanged. We override the stepBy method, which is called whenever the value of the widget is changed, and emit the timeChanged signal only when the time component of the QDateTime object changes.

Connecting the signal

Finally, we need to connect the timeChanged signal to a slot that will be called whenever the signal is emitted.

def on_time_changed():
    print("Time changed:", date_edit.time().toString("yyyy-MM-dd HH:mm:ss"))

time_edit = TimeEdit()
time_edit.setDateTime(QDateTime.currentDateTime())
time_edit.timeChanged.connect(on_time_changed)

Here, we define a new slot called on_time_changed that will be called whenever the timeChanged signal is emitted. We create a new TimeEdit widget and connect its timeChanged signal to the on_time_changed slot.

Conclusion

In this tutorial, we learned how to emit a signal only when the time changes in a PyQt5 QDateTimeEdit widget. We defined a custom signal that is emitted only when the time component of the underlying QDateTime object changes. We also connected the signal to a slot that was called whenever the signal was emitted.