QList getter functions problems

int MerchandiseTableModel::rowCount(const QModelIndex& parent) const{    Q_UNUSED(parent);    return merchandiseList().size();}QVariant MerchandiseTableModel::data(const QModelIndex& index,                                     int role) const{    MerchandiseItem currentItem=merchandiseList().at(index.row());    if(!index.isValid())        return QVariant();    if(index.row()>=merchandiseList().size() || index.row()<0)        return QVariant();/*    if(role==Qt::DisplayRole)    {        if(index.column()==static_cast<int>(COLUMN_NAME))            return currentItem.merchandiseName();    }   // display role handling*/    if(role==Qt::DecorationRole)    {        return currentItem.merchandisePic();    }   // decoration role handling (pixmap setup)    return QVariant();}Here are errors:src\features\eMenu\merchandisetablemodel.cpp: In member function 'virtual int MerchandiseTableModel::rowCount(const QModelIndex&) const':src\features\eMenu\merchandisetablemodel.cpp:19: error: passing 'const MerchandiseTableModel' as 'this' argument of 'QList<MerchandiseItem>& MerchandiseTableModel::merchandiseList()' discards qualifierssrc\features\eMenu\merchandisetablemodel.cpp: In member function 'virtual QVariant MerchandiseTableModel::data(const QModelIndex&, int) const':src\features\eMenu\merchandisetablemodel.cpp:31: error: passing 'const MerchandiseTableModel' as 'this' argument of 'QList<MerchandiseItem>& MerchandiseTableModel::merchandiseList()' discards qualifierssrc\features\eMenu\merchandisetablemodel.cpp:36: error: passing 'const MerchandiseTableModel' as 'this' argument of 'QList<MerchandiseItem>& MerchandiseTableModel::merchandiseList()' discards qualifiersmingw32-make[1]: Leaving directory `C:/Users/Uporabnik/Desktop/working_copy/ClientDemo'mingw32-make: Leaving directory `C:/Users/Uporabnik/Desktop/working_copy/ClientDemo'mingw32-make[1]: *** [debug/merchandisetablemodel.o] Error 1mingw32-make: *** [debug] Error 2Končal s kodo 2.Well, here is header file:class MerchandiseTableModel : public QAbstractTableModel{Q_OBJECTpublic:    explicit MerchandiseTableModel(QObject *parent=0);    MerchandiseTableModel(QList<MerchandiseItem> merchandiseList,                          QObject* parent=0);    int rowCount(const QModelIndex& parent) const;    int columnCount(const QModelIndex& parent) const;    QVariant data(const QModelIndex& index,                  int role) const;    QVariant headerData(int section,                        Qt::Orientation orientation,                        int role) const;    Qt::ItemFlags flags(const QModelIndex& index) const;    bool setData(const QModelIndex&index,                 const QVariant& value,                 int role=Qt::EditRole);    bool insertRows(int position,                    int rows,                    const QModelIndex& index=QModelIndex());    bool removeRows(int position,                    int rows,                    const QModelIndex& index=QModelIndex());    inline QList<MerchandiseItem>& merchandiseList()        { return m_MerchandiseList; }private:    QList<MerchandiseItem> m_MerchandiseList;};