Sending the current displayed index of item in QComboBox at start up

Question

Using signal and slots method to get index and text of selected items in QcomboBox is well known. The code below is an illustration of that. But how can I tell my code to recieve and send the first display item at startup, Methods like Activated, currentIndexChanged, Highlighted only work by dropdown QCombobox.

Output:

1
item2
2
item3

The sample code:

from PyQt5 import QtCore, QtWidgets, QtGui

class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.setLayout(QtWidgets.QVBoxLayout())
        combo = QtWidgets.QComboBox(self)
        self.layout().addWidget(combo)
        combo.addItems(["item1", "item2", "item3"])
        combo.setMinimumWidth(150)
        combo.activated[int].connect(self.onActivatedIndex)
        combo.activated[str].connect(self.onActivatedText)

    @QtCore.pyqtSlot(int)
    def onActivatedIndex(self, index):
        print(index)

    @QtCore.pyqtSlot(str)
    def onActivatedText(self, text):
        print(text)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

nathancy · Accepted Answer · 2019-06-12T01:00:14.310

You could make your own custom signal and emit that in the __init__ section of your object. This signal could then access the first item in the QComboBox. Another method could be to use a singleShot timer but making a custom signal would probably be better. You can retrieve the current index with currentIndex() or currentText().

from PyQt5 import QtCore, QtWidgets, QtGui

class Widget(QtWidgets.QWidget):
    startup = QtCore.pyqtSignal()

    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.setLayout(QtWidgets.QVBoxLayout())
        self.combo = QtWidgets.QComboBox(self)
        self.layout().addWidget(self.combo)
        self.combo.addItems(["item1", "item2", "item3"])
        self.combo.setMinimumWidth(150)
        self.combo.activated[int].connect(self.onActivatedIndex)
        self.combo.activated[str].connect(self.onActivatedText)

        self.startup.connect(self.current_index)
        self.startup.emit()

    @QtCore.pyqtSlot()
    def current_index(self):
        print(self.combo.currentIndex())
        print(self.combo.currentText())

    @QtCore.pyqtSlot(int)
    def onActivatedIndex(self, index):
        print(index)

    @QtCore.pyqtSlot(str)
    def onActivatedText(self, text):
        print(text)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

score 0 · Answer 2 · answered Jun 12 '19 at 01:13

Try it:

from PyQt5 import QtCore, QtWidgets, QtGui

class Widget(QtWidgets.QWidget):
    def __init__(self, parent=None):
        QtWidgets.QWidget.__init__(self, parent)
        self.setLayout(QtWidgets.QVBoxLayout())
        self.combo = QtWidgets.QComboBox(self)
        self.layout().addWidget(self.combo)
        self.combo.addItems(["item1", "item2", "item3"])
        self.combo.setMinimumWidth(150)

        self.combo.activated[int].connect(self.onActivatedIndex)
        self.combo.activated[str].connect(self.onActivatedText)

        self.combo.activated.emit(1)                           # <---

    @QtCore.pyqtSlot(int)
    def onActivatedIndex(self, index):
        print("\nindex->", index)
        print("text ->", self.combo.itemText(index))

    @QtCore.pyqtSlot(str)
    def onActivatedText(self, text):
        print(text)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = Widget()
    w.show()
    sys.exit(app.exec_())

Sending the current displayed index of item in QComboBox at start up

2 Answers2