Sure, I attached the proxyFilter code. What's also interessting that if I click into the treeview I get a bunch of cout's from the setData instead just a single one.

Qt Code: 
  1. snip main.cpp
  2.  
  3.    TestModel model;
  4.    QSplitter *splitter = new QSplitter;
  5.    QTreeView *tree = new QTreeView(splitter);
  6.    QTableView *table = new QTableView(splitter);
  7.  
  8.    table->setModel(&model);
  9.    table->setRootIndex(QModelIndex());
  10.  
  11.    ProxyFilter filterModel;
  12.    filterModel.setSourceModel(&model);
  13.    tree->setModel(&filterModel);
  14.  
  15.    splitter->setWindowTitle("Test views");
  16.    splitter->show();
  17.  
  18. 	return app.exec();
  19. }
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proxyFilter.cpp:
Qt Code: 
  1. #include "proxyFilter.h"
  2. #include <iostream>
  3.  
  4. ProxyFilter::ProxyFilter() {
  5. }
  6.  
  7. ProxyFilter::~ProxyFilter() {
  8. }
  9.  
  10. QModelIndex ProxyFilter::mapFromSource (const QModelIndex & sourceIndex) const {
  11.  
  12.   std::cout << "mapFromSource" << std::endl;
  13.  
  14.   if(sourceIndex.isValid())
  15.     return createIndex(sourceIndex.row(), sourceIndex.column());
  16.   else
  17.     return QModelIndex();
  18. }
  19.  
  20. QModelIndex ProxyFilter::mapToSource (const QModelIndex & proxyIndex) const {
  21.  
  22.   std::cout << "mapToSource" << std::endl;
  23.   return sourceModel()->index(proxyIndex.row(), proxyIndex.column());
  24. }
  25.  
  26.  
  27. int ProxyFilter::columnCount(const QModelIndex & parent) const {
  28.  
  29. //  return sourceModel()->columnCount(parent);
  30.  
  31. // filter out all cols - keep only col = 0
  32.   return 1;
  33.  
  34. }
  35.  
  36. int ProxyFilter::rowCount(const QModelIndex & parent) const {
  37.   return sourceModel()->rowCount(parent);
  38. }
  39.  
  40.  
  41. QModelIndex ProxyFilter::index(int row, int column, const QModelIndex& parent) const {
  42.  
  43.   return sourceModel()->index(row, column, parent);
  44.  
  45. }
  46.  
  47. QModelIndex ProxyFilter::parent(const QModelIndex&) const {
  48.  
  49.   return QModelIndex();
  50. }
  51.  
  52. QVariant ProxyFilter::data(const QModelIndex & index, int role) const {
  53.  
  54.   std::cout << "data: row =" << index.row() << " col=" << index.column() << std::endl;
  55.   return sourceModel()->data(index, role);
  56.  
  57. }
  58.  
  59. bool ProxyFilter::setData(const QModelIndex &index, const QVariant &value, int role) {
  60.  
  61.   std::cout << "setData: row =" << index.row() << " col=" << index.column() << std::endl;
  62.   return sourceModel()->setData(index, value, role);
  63.  
  64. }
  65.  
  66. Qt::ItemFlags ProxyFilter::flags(const QModelIndex &index) const {
  67.  
  68.   return sourceModel()->flags(index);
  69.  
  70. }
  71.  
  72. void ProxyFilter::setSourceModel(QAbstractItemModel *sourceModel) {
  73.  
  74.   connect(sourceModel, SIGNAL(modelReset()), this, SIGNAL(modelReset()));
  75.   QAbstractProxyModel::setSourceModel(sourceModel);
  76.  
  77. }
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proxyFilter.h:
Qt Code: 
  1. #ifndef PROXYFILTER_H
  2. #define PROXYFILTER_H
  3.  
  4. #include <QAbstractProxyModel>
  5. #include <QAbstractItemModel>
  6.  
  7. class ProxyFilter : public QAbstractProxyModel {
  8.  
  9. Q_OBJECT  
  10.  
  11. public:
  12.  
  13.   ProxyFilter();
  14.   ~ProxyFilter();
  15.  
  16.   int columnCount(const QModelIndex & parent = QModelIndex()) const;
  17.   int rowCount(const QModelIndex & parent = QModelIndex()) const;
  18.  
  19.   QModelIndex mapFromSource (const QModelIndex & sourceIndex) const;
  20.   QModelIndex mapToSource (const QModelIndex & proxyIndex) const;
  21.  
  22.   QModelIndex index(int row, int column, const QModelIndex& parent = QModelIndex()) const;
  23.   QModelIndex parent(const QModelIndex&) const ;
  24.  
  25.   QVariant data(const QModelIndex & index, int role) const;
  26.   bool setData (const QModelIndex &index, const QVariant &value, int role);
  27.  
  28.   Qt::ItemFlags flags(const QModelIndex &index) const;
  29.  
  30.   void setSourceModel(QAbstractItemModel *sourceModel);
  31.  
  32. };
  33.  
  34. #endif
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