After adding row to a parent node, modify parent to show number of children below

Question

I'm looping through my data, using addrow to either the root node or to parent off it (etc.). Now for the parent how to modify the 2nd cell in the parent to show the current number of children, then update that cell, as I add more children?

Answer 1

One possible solution is to use the rowsInserted and rowsRemoved signals from the model to calculate the number of children. On the other hand, a simpler solution is to use a delegate:

import random

from PyQt5 import QtCore, QtGui, QtWidgets


class Delegate(QtWidgets.QStyledItemDelegate):
    def initStyleOption(self, option, index):
        super().initStyleOption(option, index)
        if not index.parent().isValid() and index.column() == 1:
            model = index.model()
            sibling = index.sibling(index.row(), 0)
            option.text = f"{model.rowCount(sibling)} childs"


def main():
    app = QtWidgets.QApplication([])

    model = QtGui.QStandardItemModel(0, 2)

    for i in range(4):
        item = QtGui.QStandardItem(f"parent-{i}")
        model.appendRow(item)

    view = QtWidgets.QTreeView()
    delegate = Delegate(view)
    view.setItemDelegate(delegate)
    view.setModel(model)
    view.resize(640, 480)
    view.show()

    def handle_timeout():
        for i in range(4):
            root_item = model.item(i)
            for j in range(random.randint(3, 5)):
                item = QtGui.QStandardItem(f"child-{i}-{j}")
                root_item.appendRow(item)
        view.expandAll()

    QtCore.QTimer.singleShot(2 * 1000, handle_timeout)

    app.exec_()


if __name__ == "__main__":
    main()