Qt MVC。视图不显示我的模型中的信息

Question

我正在尝试实现自己的qfilesystemmodel。我的项目可以编译并运行，项目中的视图不显示模型中的任何内容。 我读到错误可能出在data（），parent（）函数中，并且我正在堆栈而不是堆中创建模型。如有必要，我可以为您提供其他函数的实现。要创建UI，我使用了Qt Designer来自模型的数据是表示绝对路径的QString。这是我的代码。

mainwindow.h

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;
    FileSystemModel *pFSmodel;
};

mainwindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{   
    ui->setupUi(this);

    pFSmodel = new FileSystemModel(QDir::homePath, this)

    ui->leftList->setModel(pFSmodel);
    ui->leftList->setRootIndex(pFSmodel->index(QDir::homePath()));

    ui->rightList->setModel(pFSmodel);
    ui->rightList->setRootIndex(pFSmodel->index(QDir::homePath()));
}

MainWindow::~MainWindow()
{
    delete ui;
}

FileSystemModel.h

class FileSystemModel : public QAbstractItemModel
{
    Q_OBJECT

public:
    FileSystemModel(QString rootPath, QObject *parent = 0);
    ~FileSystemModel();

    QVariant data(const QModelIndex &index, int role) const;
    Qt::ItemFlags flags(const QModelIndex &index) const;
    QVariant headerData(int section, Qt::Orientation orientation,
                        int role = Qt::DisplayRole) const;
    QModelIndex index(int row, int column,
                      const QModelIndex &parent = QModelIndex()) const;
    QModelIndex index(QString rootPath);
    QModelIndex parent(const QModelIndex &index) const;
    QFileInfo fileInfo(const QModelIndex &index);
    void fetchMore(const QModelIndex &parent);
    int rowCount(const QModelIndex &parent = QModelIndex()) const;
    int columnCount(const QModelIndex &parent = QModelIndex()) const;
    bool hasChildren(const QModelIndex &parent) const;
    bool canFetchMore(const QModelIndex &parent) const;

private:
    void setupModelData(const QString &rootPath);
    FileItem* itemForIndex(const QModelIndex& index)const;

    FileItem *rootItem_p;
    QFileIconProvider iconProvider;
};

FileSystemModel.cpp

FileSystemModel::FileSystemModel(QString rootPath, QObject *parent_p):
    QAbstractItemModel(parent_p)
{
    rootItem_p = new FileItem(QVariant(rootPath), true, nullptr);
    setupModelData(rootPath);
}

QModelIndex FileSystemModel::parent(const QModelIndex &index) const
{
    if (!index.isValid())
        return QModelIndex();

    if (FileItem *childItem_p = itemForIndex(index)){
        if (FileItem *parentItem_p = childItem_p->parentItem()){
            if (parentItem_p == rootItem_p)
                return QModelIndex();
            if (FileItem *grandParentItem_p = parentItem_p->parentItem()){
                int row = grandParentItem_p->rowOfChild(parentItem_p);
                return createIndex(row, 0, parentItem_p);
            }
        }
    }
    return QModelIndex();
}

QVariant FileSystemModel::data(const QModelIndex &index, int role) const
{
    if (!rootItem_p || !index.isValid() || index.column() < 0 || index.column() > columnCount())
        return QVariant();

    if (FileItem *item_p = itemForIndex(index)){
        if (role == Qt::DisplayRole){
            QVariant variant = QVariant(item_p->data(0));
            return variant;
        }
        QVariant data = item_p->data(0);
        if (role == Qt::DecorationRole && data.isValid()){
            QFileInfo info = QFileInfo(data.toString());
            return iconProvider.icon(info);
        }
    }

    return QVariant();
}

void FileSystemModel::setupModelData(const QString &rootPath)
{
    QDirIterator it(rootPath);

    beginResetModel();
    rootItem_p = new FileItem(QVariant(rootPath), true, 0);
    rootItem_p->set_fetched(true);
    rootItem_p->set_exist(true);
    while (it.hasNext()){
        it.next();
        QFileInfo fileInfo = it.fileInfo();
        FileItem *item_p = new FileItem(fileInfo.absoluteFilePath(), fileInfo.isDir(), rootItem_p);
        item_p->set_fetched(true);
        item_p->set_exist(true);
        rootItem_p->addChild(item_p);
    }
    endResetModel();
}

QModelIndex FileSystemModel::index(QString rootPath)
{
    QPair<FileItem*, int> pr = rootItem_p->findItem(QVariant(rootPath));

    if (pr.first == nullptr)
        return QModelIndex();
    else{
        FileItem *item_p = pr.first;
        int row = pr.second;
        return createIndex(row, 0, item_p);
    }

}

FileItem.h

class FileItem{
public:
    FileItem(QVariant maybeFilePath, bool fileIsDir, FileItem *parentItem_p);
    FileItem();
    ~FileItem();

    void addChild(FileItem *child_p);
    FileItem *child(int row);
    int childCount() const;
    int columnCount() const;
    int row() const;
    int rowOfChild(FileItem *child_p) const;
    QVariant data(int column) const;
    FileItem *parentItem();
    QPair<FileItem*, int> findChild(Predicate pred);
    QPair<FileItem*, int> findItem(Predicate pred);
    QPair<FileItem*, int> findChild(QVariant data);
    QPair<FileItem*, int> findItem(QVariant data);
    void set_dir(bool status);
    void set_fetched(bool status);
    void set_exist(bool status);
    bool checkDir()const;
    bool checkFetched()const;
    bool checkExist()const;


private:
    bool exist;
    bool is_dir;
    bool is_fetched;
    FileItem *parentItem_p;
    QVector<FileItem*> childrenPtrs;
    QVariant itemData;
};