QSortFilterProxyModel and QSqlRelationalDelegate in TableView

Hello,
step by step I'm learning from here but unfortunately I've a question more:

When I use a QSqlRelationalTableModel with a TableView and a QSqlRelationalDelegate I can see relations as correct entries and get a combobox when selecting it for editing. But when I use a QSortFilterProxyModel, the entries are correct, but the Combobox is not shown when I want to edit I have to enter the key-vaues when I want to edit the field (which works but is not user friendly). Is there a way to get a ComboBox for them even if I use a ProxyModel?

Thanks for any help
Armin

In the example, when I comment Line 44 and uncomment line 41 it works as expected, getting a ComboBox when double-cilciking in the color-table's other-column (but without the model wich I need for sorting).

mainwindow.cpp

Code:

#include <QtGui>
#include <QtSql>
#include "mainwindow.h"
MainWindow::MainWindow()
{
  createOtherDock();
  createColorDock();
}
//---------------------------------------------------------------------------
void MainWindow::createOtherDock()
{
  QDockWidget *dock = new QDockWidget(tr("Other"), this);
 
  otherModel = new QSqlRelationalTableModel(this);
  otherModel->setTable("other");
  otherModel->select();
 
  otherView = new QTableView(dock);
  otherView->setModel(otherModel);
 
  dock->setWidget(otherView);
  addDockWidget(Qt::RightDockWidgetArea, dock);
}
//---------------------------------------------------------------------------
void MainWindow::createColorDock()
{
  QDockWidget *dock = new QDockWidget(tr("Color"), this);
 
  colorModel = new QSqlRelationalTableModel(this);
  colorModel->setTable("color");
  colorModel->setRelation(color_Other, QSqlRelation("other", "id", "name"));
  colorModel->select();
 
  MyProxyModel = new QSortFilterProxyModel(this);
  MyProxyModel->setSourceModel(colorModel);
  MyProxyModel->sort(1, Qt::DescendingOrder);
 
  colorView = new QTableView(dock);
 
// without Proxy I get a ComboBox
//  colorView->setModel(colorModel);
 
  // with Proxy I get no ComboBox
  colorView->setModel(MyProxyModel);
 
  // tried QStyledItemDelegate also, no success
  colorView->setItemDelegate(new QSqlRelationalDelegate(this));
 
  dock->setWidget(colorView);
  addDockWidget(Qt::RightDockWidgetArea, dock);
}

mainwindow.h

Code:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QtGui>
#include <QtSql>
 
enum {
  other_Id = 0,
  other_Name = 1,
};
enum {
  color_Id = 0,
  color_Name = 1,
  color_Other = 2,
};
 
class MainWindow : public QMainWindow
{
  Q_OBJECT
 
public:
  MainWindow();
 
private:
  void createOtherDock();
  void createColorDock();
 
  QSqlRelationalTableModel *otherModel;
  QSqlRelationalTableModel *colorModel;
 
  QTableView *otherView;
  QTableView *colorView;
 
  QSortFilterProxyModel *MyProxyModel;
};
#endif

main.cpp creates some data to play with

Code:

#include <QApplication>
#include <QtGui>
#include <QtSql>
 
#include "mainwindow.h"
//---------------------------------------------------------------------------
bool Connect()
{
  QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
  db.setDatabaseName("data.dat");
  if (!db.open())
  {
      QMessageBox::warning(0, QObject::tr("Error"), db.lastError().text());
      return (false);
  }
  return (true);
}
//---------------------------------------------------------------------------
void createDataBase()
{
  QSqlQuery query;
  query.exec("DROP TABLE other");
  query.exec("DROP TABLE color");
 
  query.exec("CREATE TABLE other ("
             "id INTEGER PRIMARY KEY AUTOINCREMENT, "
             "name VARCHAR(10) NOT NULL)");
 
  query.exec("CREATE TABLE color ("
             "id INTEGER PRIMARY KEY AUTOINCREMENT, "
             "name VARCHAR(40) NOT NULL, "
             "otherid INTEGER NOT NULL, "
             "FOREIGN KEY (otherid) REFERENCES other)");
 
  query.prepare("INSERT INTO other (id, name) "
                  "VALUES (:id, :name)");
  query.bindValue(":id", 1);
  query.bindValue(":name", "A");
  query.exec();
  query.bindValue(":id", 2);
  query.bindValue(":name", "b");
  query.exec();
  query.bindValue(":id", 3);
  query.bindValue(":name", "C");
  query.exec();
 
  query.prepare("INSERT INTO color (id, name, otherid) "
                 "VALUES (:id, :name, :otherid)");
  query.bindValue(":id", 1);
  query.bindValue(":name", "Red");
  query.bindValue(":otherid", 1);
  query.exec();
  query.bindValue(":id", 2);
  query.bindValue(":name", "Green");
  query.bindValue(":otherid", 2);
  query.exec();
  query.bindValue(":id", 3);
  query.bindValue(":name", "Blue");
  query.bindValue(":otherid", 3);
  query.exec();
}
//---------------------------------------------------------------------------
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
 
  bool existingData = QFile::exists("data.dat");
  if (!Connect())
  {
    return(1);
  }
  if (!existingData)
  {
    createDataBase();
  }
  MainWindow Window;
  Window.show();
//  Window.filterColorView();
  return app.exec();
}

Qt Creator project-file

Code:

QT += sql
SOURCES += main.cpp \
    mainwindow.cpp
HEADERS += mainwindow.h