Using proxy models - c++

Question

I've created Proxy model by subclassing QAbstractProxyModel and connected it as a model to my view. I also set up source model for this proxy model. Unfortunately something is wrong because I'm not getting anything displayed on my listView (it works perfectly when I have my model supplied as a model to view but when I supply this proxy model it just doesn't work). Here are some snippets from my code:
#ifndef FILES_PROXY_MODEL_H
#define FILES_PROXY_MODEL_H
#include <QAbstractProxyModel>
#include "File_List_Model.h"
class File_Proxy_Model: public QAbstractProxyModel
{
public:
explicit File_Proxy_Model(File_List_Model* source_model)
{
setSourceModel(source_model);
}
virtual QModelIndex mapFromSource(const QModelIndex & sourceIndex) const
{
return index(sourceIndex.row(),sourceIndex.column());
}
virtual QModelIndex mapToSource(const QModelIndex & proxyIndex) const
{
return index(proxyIndex.row(),proxyIndex.column());
}
virtual int columnCount(const QModelIndex & parent = QModelIndex()) const
{
return sourceModel()->columnCount();
}
virtual int rowCount(const QModelIndex & parent = QModelIndex()) const
{
return sourceModel()->rowCount();
}
virtual QModelIndex index(int row, int column, const QModelIndex & parent = QModelIndex()) const
{
return createIndex(row,column);
}
virtual QModelIndex parent(const QModelIndex & index) const
{
return QModelIndex();
}
};
#endif // FILES_PROXY_MODEL_H
//and this is a dialog class:
Line_Counter::Line_Counter(QWidget *parent) :
QDialog(parent), model_(new File_List_Model(this)),
proxy_model_(new File_Proxy_Model(model_)),
sel_model_(new QItemSelectionModel(proxy_model_,this))
{
setupUi(this);
setup_mvc_();
}
void Line_Counter::setup_mvc_()
{
listView->setModel(proxy_model_);
listView->setSelectionModel(sel_model_);
}

Answer 1

mapToSource should return an index from the source model:
virtual QModelIndex mapToSource(const QModelIndex & proxyIndex) const
{
return sourceModel()->index(proxyIndex.row(),proxyIndex.column());
}
I tested with that code:
#include <QtGui>
#include "file_proxy_model.h"
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QDir dir(QDesktopServices::storageLocation(QDesktopServices::HomeLocation));
File_List_Model model(dir.entryList());
File_Proxy_Model proxy(&model);
QListView listView;
listView.setModel(&proxy);
listView.show();
return a.exec();
}
// In "File_List_Model.h"
class File_List_Model : public QStringListModel
{
public:
explicit File_List_Model(const QStringList & list, QObject *parent = 0)
: QStringListModel(list, parent)
{
}
};