I have used QStandardItem::SetData to save data for each tree item, code is below:
m_htHashItem->setData(QVariant(QVariant::UserType, m_pCurrMapData), MyClassRole);

Now I need to retrieve it back on item click event
MAP_DATA* p = static_cast< MAP_DATA *> (index.data(MyClassRole).value());

but I am getting error:
error: C2783: 'T QVariant::value(void) const' : could not deduce template argument for 'T'