pyQt: How do I update a label?

T.T. picture T.T. · Apr 13, 2016 · Viewed 31.7k times · Source

I created this simple UI with qtDesigner and I want to update my label every 10 seconds with the value of a function, but I have no idea how to do this.I've tried different things but nothing worked.

def example():
    ...
    return text

UI:

class Ui_Form(object):
    def setupUi(self, Form):
        Form.setObjectName("Form")
        Form.resize(400, 300)
        self.label = QtWidgets.QLabel(Form)
        self.label.setGeometry(QtCore.QRect(165, 125, 61, 16))
        self.label.setObjectName("label")

        self.retranslateUi(Form)
        QtCore.QMetaObject.connectSlotsByName(Form)

    def retranslateUi(self, Form):
        _translate = QtCore.QCoreApplication.translate
        Form.setWindowTitle(_translate("Form", "Form"))
        self.label.setText(_translate("Form", plsupdatethis)

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    Form = QtWidgets.QWidget()
    ui = Ui_Form()
    ui.setupUi(Form)
    Form.show()
    sys.exit(app.exec_())

Answer

Brendan Abel picture Brendan Abel · Apr 13, 2016

Ideally, you would create a subclass of QWidget (instead of simply instantiating it the way you are doing with Form). But here is a way you could do it with minimal changes.

You have a function that is capable of updating the label. Then use a QTimer to trigger it at regular intervals (in this case, every 10 seconds).

import datetime

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    Form = QtWidgets.QWidget()
    ui = Ui_Form()
    ui.setupUi(Form)
    Form.show()

    def update_label():
        current_time = str(datetime.datetime.now().time())
        ui.label.setText(current_time)

    timer = QtCore.QTimer()
    timer.timeout.connect(update_label)
    timer.start(10000)  # every 10,000 milliseconds

    sys.exit(app.exec_())