QFileSystemModel

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include <QFileSystemModel>

class FileSystemModel : public QFileSystemModel
{
public:

    explicit FileSystemModel(QObject *parent = nullptr) : QFileSystemModel(parent) {}

    enum Roles {
        FileSizeRole = Qt::UserRole + 1
    };

    QVariant data(const QModelIndex &index, int role) const
    {
        switch (role) {
        case FileSizeRole:
            return QFileSystemModel::data(this->index(index.row(), 1, index.parent()),
                                          Qt::DisplayRole);
        default:
            return QFileSystemModel::data(index, role);
        }
    }

    QHash<int, QByteArray> roleNames() const
    {
        auto result = QFileSystemModel::roleNames();
        result.insert(FileSizeRole, "fileSize");
        return result;
    }
};

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    FileSystemModel *model = new FileSystemModel(&app);
    model->setRootPath("/");
    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("fsModel", model);
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

main.qml

import QtQuick 2.9
import QtQuick.Window 2.2
import QtQuick.Controls 1.4

Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")

    TreeView {
        model: fsModel
        anchors.fill: parent

        TableViewColumn {
            role: "display"
        }
        TableViewColumn {
            role: "fileSize"
        }
    }
}