I 'm subclassing the QSqlRelationalDelegate and I have this (working) python code which I 'm trying to convert to Qt c++:
Qt Code: 
  1. def createEditor(self, parent, option, index):
  2.         # column of combo box 'position'
  3.         positionColumn = 2
  4.         print("myDelegate.createEditor index.column()=" + str(index.column()) + " option=" + str(option) )
  5.         if index.column() == positionColumn:
  6.             editor = QSqlRelationalDelegate.createEditor(self, parent, option, index)
  7.             if isinstance(editor, QComboBox):
  8.                 editor.model().select()
  9.             return editor
  10.         else:
  11.             return super(myDelegate, self).createEditor(parent, option, index)
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What I 've done so far (don't take it as correct, it's just an effort, it's not working):
Qt Code: 
  1. QWidget *BookDelegate::createEditor(QWidget *parent,
  2.                                     const QStyleOptionViewItem &option,
  3.                                     const QModelIndex &index) const
  4. {
  5.     int positionColumn = 2;
  6.     qDebug()<< "BookDelegate.createEditor index.column()=" << (index.column()) << " option=" << option ;
  7.     if (index.column() == positionColumn){        
  8.         QWidget *editor = QSqlRelationalDelegate::createEditor(parent, option, index);
  9.         //QComboBox *editor = new QComboBox(parent);
  10.         //QSqlRelationalTableModel *model = qobject_cast <QSqlRelationalTableModel*>(index.model());
  11.         ///QComboBox* myCombo = qobject_cast <QComboBox*>(editor);
  12.         editor->model()->select();
  13.         return editor;
  14.  
  15.     }
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Any help is welcome.