How to programatically change value of QItemDelegate in QT

Question

I already checked a lot of the topics that seemed similar but they didn't help so I am asking this question. If you know of any duplicate question that is already present please direct me to it.

My Situation:

I have a (QCombobox) QItemDelegate for 1 column of a QTableView with a QStandardModel. Now it works fine when I directly edit the value or use the combobox for selection. But i am also trying to provide an option for saving the state of the table so i can reload it when required.

The Problem:

While reloading when I set the item programatically, it doesn't get reflected in the table.

I tried both

1) getting the index & using setData and

2) retrieving the QStandardItem & setting the text.

I also found that the setEditorData is not getting invoked. What am I doing wrong? How do i set the value of such a cell through code?

EDIT: some details

I subclassed the QItemDelegate as DropDown.

dropdown.h

#ifndef DROPDOWN_H
#define DROPDOWN_H

#include <QItemDelegate>
#include <QWidget>
#include <QStringListModel>
#include <QStringList>

class DropDown : public QItemDelegate
{
    Q_OBJECT
public:
    explicit DropDown(QObject *parent = 0);

    QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const;
    void setEditorData(QWidget *editor, const QModelIndex &index) const;
    void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const;
    void updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const;
    void setComboData(QStringList list);
    QStringList getComboData();

private:
    QStringListModel *listmodel;

signals:

public slots:

};

#endif // DROPDOWN_H

dropdown.cpp

#include "dropdown.h"
#include <QComboBox>

DropDown::DropDown(QObject *parent) :
    QItemDelegate(parent)
{
    listmodel = new QStringListModel(parent);
}

QWidget *DropDown::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QComboBox *editor = new QComboBox(parent);
    editor->setEditable(true);
    editor->setInsertPolicy(QComboBox::NoInsert);
    editor->setModel(listmodel);
    return editor;
}

void DropDown::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    QString value = index.model()->data(index,Qt::EditRole).toString();
    QComboBox *original = static_cast<QComboBox *>(editor);
    original->setCurrentIndex(original->findText(value));
}

void DropDown::setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const
{    
    QComboBox *original = static_cast<QComboBox *>(editor);
    QString value = original->currentText();
    model->setData(index, value, Qt::EditRole);
}

void DropDown::updateEditorGeometry(QWidget *editor, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    editor->setGeometry(option.rect);
}

void DropDown::setComboData(QStringList list)
{
    listmodel->setStringList(list);
}

QStringList DropDown::getComboData()
{
    return listmodel->stringList();
}

and this is how it is used in the table.

model = new QStandardItemModel(0,11, this);//i update row count later while adding items.
ui->itemTable->setModel(model);

sourceSet = new DropDown(this);
ui->itemTable->setItemDelegateForColumn(3, sourceSet);