QComboBox add bold parent items

Question

I would like to add some kind of parent items to a pyqt5 combobox which allow grouping of the items below. the parents should be not selectable and bold if possible, the children a little bit indented.

What I have got so far: I got them bold but I have no idea about the not-selectable option. I could add .setEnabled(False) but this greys them out. also maybe there is a nicer way than adding simply blanks in front of the children items?

from PyQt5.QtWidgets import QWidget, QComboBox, QApplication
import PyQt5.QtGui
import sys


class Example(QWidget):

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


    def initUI(self):

        combo = QComboBox(self)

        combo.addItem("option_1")
        combo.addItem("group_1")
        combo.addItem("   option_2")
        combo.addItem("   option_3")
        combo.addItem("group_2")
        combo.addItem("   option_4")
        combo.addItem("   option_5")


        font = PyQt5.QtGui.QFont()
        font.setBold(True)

        item = combo.model().item(1, 0)  # group_1 bold
        item.setFont(font)

        item = combo.model().item(4, 0)  # group_2 bold
        item.setFont(font)


        combo.currentTextChanged.connect(lambda : print(combo.currentText()) )

        self.setGeometry(100, 100, 300, 100)
        self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

how current code looks like:

Answer 1

You can create a custom model that implements the logic of the groups. To disable the selection you must use the flags. To establish indentation using a delegate next to a role. You should not use the addItem method of the QComboBox but the model.

from PyQt5 import QtCore, QtGui, QtWidgets


GroupRole = QtCore.Qt.UserRole


class GroupDelegate(QtWidgets.QStyledItemDelegate):
    def initStyleOption(self, option, index):
        super(GroupDelegate, self).initStyleOption(option, index)
        if not index.data(GroupRole):
            option.text = "   " + option.text


class GroupItem(QtGui.QStandardItem):
    def __init__(self, text):
        super(GroupItem, self).__init__(text)
        self.setData(True, GroupRole)
        self._number_of_childrens = 0
        font = self.font()
        font.setBold(True)
        self.setFont(font)
        self.setFlags(self.flags() & ~QtCore.Qt.ItemIsSelectable)

    def addChild(self, text):
        it = QtGui.QStandardItem(text)
        it.setData(False, GroupRole)
        self._number_of_childrens += 1
        self.model().insertRow(self.row() + self._number_of_childrens, it)
        return it


class GroupComboBox(QtWidgets.QComboBox):
    def __init__(self, parent=None):
        super(GroupComboBox, self).__init__(parent)
        self.setModel(QtGui.QStandardItemModel(self))
        delegate = GroupDelegate(self)
        self.setItemDelegate(delegate)

    def addGroup(self, text):
        it = GroupItem(text)
        self.model().appendRow(it)
        return it

    def addChild(self, text):
        it = QtGui.QStandardItem(text)
        it.setData(True, GroupRole)
        self.model().appendRow(it)


class Example(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()
        self.initUI()

    def initUI(self):
        combo = GroupComboBox()

        combo.addChild("option_1")

        group1 = combo.addGroup("group_1")
        group1.addChild("option_2")
        group1.addChild("option_3")

        group2 = combo.addGroup("group_2")
        group2.addChild("option_4")
        group2.addChild("option_5")

        lay = QtWidgets.QVBoxLayout(self)
        lay.addWidget(combo)

        self.resize(160, 60)


if __name__ == "__main__":
    import sys

    app = QtWidgets.QApplication(sys.argv)
    ex = Example()
    ex.show()
    sys.exit(app.exec_())