Qt - Triggering an event when selection of abstract item delegate changes - qt

Question

I am trying to make a tableview with a row which has a separate dropdown for each column. The user can only select a combination of values. That is, if the user selects "A" from the first drop down, the values in the other drop downs should be updated to that which can match "A".
I have made my AbsractItemDelegate class and the values are being assigned fine. But I am stuck up at how I can trigger an event when a value changes in one of the drop downs.
Thanks.
The following is my delegate class implementation:
FillComboBox::FillComboBox(QStringList the_list) : QItemDelegate() {
//list = new QStringList();
list = the_list; }
QWidget* FillComboBox::createEditor(QWidget* parent,
const QStyleOptionViewItem& /* option */,
const QModelIndex& /* index */) const {
QComboBox* editor = new QComboBox(parent);
editor->addItems(list);
editor->setCurrentIndex(2);
return editor; }
void FillComboBox::setEditorData(QWidget* editor,
const QModelIndex &index) const {
QString text = index.model()->data(index, Qt::EditRole).toString();
QComboBox* combo_box = dynamic_cast<QComboBox*>(editor);
combo_box->setCurrentIndex(combo_box->findText(text)); }
void FillComboBox::setModelData(QWidget* editor, QAbstractItemModel* model,
const QModelIndex &index) const {
QComboBox* combo_box = dynamic_cast<QComboBox*>(editor);
QString text = combo_box->currentText();
model->setData(index, text, Qt::EditRole); }
void FillComboBox::updateEditorGeometry(QWidget* editor,
const QStyleOptionViewItem &option, const QModelIndex &/* index */) const {
editor->setGeometry(option.rect); }

Answer 1

You can update the data of the "other" item as soon as the current item's data is updating, i.e. in FillComboBox::setModelData(). Please find the pseudo code that implements desired behavior (see comments):
void FillComboBox::setModelData(QWidget* editor, QAbstractItemModel* model,
const QModelIndex &index) const
{
QComboBox* combo_box = dynamic_cast<QComboBox*>(editor);
QString text = combo_box->currentText();
model->setData(index, text, Qt::EditRole);
// Find the model index of the item that should be changed and its data too
int otherRow = ...; // find the row of the "other" item
int otherColumn = ...; // find the column of the "other" item
QModelIndex otherIndex = model->index(otherRow, otherColumn);
QString newText = text + "_new";
// Update other item too
model->setData(otherIndex, newText, Qt::EditRole);
}