qlistview with checkboxes using custom model

Question

I have subclassed filesystemmodel to include checkboxes in listview , which is working fine. My problem is whenever I click an item the text of that item disappears and when i click another item the text of previously selected item becomes visible. Can anyone please tell me the reason behind it.

Here is the code i implemented.

Please tell me what i am missing here, Thanks

#include "custommodel.h"
#include <iostream>

using namespace std;

CustomModel::CustomModel()
{

}

QVariant CustomModel::data(const QModelIndex& index, int role) const
{
    QModelIndex parent=this->parent(index);
    if(role == Qt::DecorationRole)
    {
        if(this->filePath(parent)=="")
        {
            return QIcon(":/Icons/HardDisk.png");
        }

        else if(this->isDir(index))
        {
            QDir dir(this->filePath(index));
            QFileInfoList files = dir.entryInfoList(QDir::NoDotAndDotDot | 
                                                    QDir::Files | QDir::Dirs);
            for(int file = 0; file < files.count(); file++)

                if(files.count()>0)
                    return QIcon(":/Icons/FullFolder.png");
            if(files.count()==0)
                return QIcon(":/Icons/EmptyFolder.png");

        }
        else{

            QFileInfo fi( this->filePath(index));
            QString ext = fi.suffix();

            if(ext=="jpeg"||ext=="jpg"||ext=="png"||ext=="bmp")
                return QIcon(filePath(index));
           }
    }

   if (role == Qt::CheckStateRole && !(this->filePath(parent)==""))
       return checklist.contains(index) ? Qt::Checked : Qt::Unchecked;
   return QFileSystemModel::data(index, role);

}

Qt::ItemFlags CustomModel::flags(const QModelIndex& index) const
{

    return QFileSystemModel::flags(index)| Qt::ItemIsUserCheckable;

}

bool CustomModel::setData(const QModelIndex& index, const QVariant& value, int role)
{

    if (role == Qt::CheckStateRole) {

        if (value == Qt::Checked)
            checklist.insert(index);
        else
            checklist.remove(index);

        emit dataChanged(index, index);
        return true;
    }
    return QFileSystemModel::setData(index, value, role);
}

Answer 1

Not sure whether it's relevant, but I found the following note at: http://doc.trolltech.com/4.6/qt.html#ItemFlag-enum

"Note that checkable items need to be given both a suitable set of flags and an initial state, indicating whether the item is checked or not. This is handled automatically for model/view components, but needs to be explicitly set for instances of QListWidgetItem, QTableWidgetItem, and QTreeWidgetItem."

As far as I can make out, your code looks correct -- but maybe try setting the ItemIsUserCheckable flag on the base QFileSystemModel class (in your custom constructor), and see if the inherited data() and setData() methods work with role=Qt::CheckStateRole. If you need to maintain a list of what's currently checked for some other reason, then go ahead and do so in your derived setData(), but still call QFileSystemModel::setData() as well.

Meanwhile, I'm looking for why my QTreeView doesn't update the timestamp when I modify a file (unless I quit and restart my app, kind of defeats the purpose!) ... looks like the dataChanged() signal isn't getting emitted.