listviewitem在QML应用程序中没有显示数据

你的主要问题是:

• MDataModel继承QAbstractTableModel而不是QAbstractListModel。这不是一个绝对的问题，因为你可以使用QAbstractTableModel，但因为你在QML中使用ListView，你应该更喜欢使用QAbstractListModel。

• 您正在混合角色和列。这是第一点的结果，因为QAbstractListModel隐藏了列的概念。

• 您没有通知模型(因此视图/QML)您更改了数据。当底层数据发生变化时，你必须通过成对调用函数来告诉模型，这取决于变化是什么:beginResetModel()/endResetModel(), beginInsertRows()/endInsertRows(), beginRemoveRows()/endRemoveRows()等。还有2个非配对信号:dataChanged()和modelReset()。请注意，您可以通过始终调用modelReset()来解决问题，但这不是一个好的做法，您应该倾向于使用最特定的函数对。

你也应该阅读Qt文档:

• 使用c++模型与Qt快速视图> QAbstractItemModel子类
• QAbstractItemModel Class>受保护的函数

这是你的固定模型。我删除了columnCount()和headerData()，因为你不需要它们来使它工作。

MDataModel.h

class MDataModel : public QAbstractListModel
{
public:
    enum Role{
            Host = Qt::UserRole,
            Service,
            Status,
            Duration,
            Info
        };
    MDataModel(QObject *parent = 0);
    QHash<int, QByteArray> roleNames() const;
    void fillData(QNetworkReply *r);
    int rowCount(const QModelIndex &parent) const;
    QVariant data(const QModelIndex &index, int role) const;
private:
    QString dataAt(int offset) const;
    QList<MDataItem*> items_;
public:
    void prepareDataFinished(QNetworkReply *r);
};

MDataModel.cpp

MDataModel::MDataModel(QObject *parent) : QAbstractListModel(parent)
{
}
int MDataModel::rowCount(const QModelIndex & /* parent */) const
{
    return items_.count();
}

QVariant MDataModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
    {
        return QVariant();
    }

    switch(role){
        // For C++ views
        case Qt::DisplayRole:
            return items_.value(index.row())->host();

        // For QML views
        case Host:
            return items_.value(index.row())->host();
        case Service:
            return items_.value(index.row())->service();
        case Status:
            return items_.value(index.row())->status();
        case Duration:
            return items_.value(index.row())->duration();
        case Info:
            return items_.value(index.row())->info();
    }
    return QVariant();
}

void MDataModel::prepareDataFinished(QNetworkReply *r)
{
    QList<MDataItem*> newItems;
    MDataItem *item = new MDataItem();
    QString data;
    while(r->canReadLine())
    {
        data = r->readLine();
            item = new MDataItem();
            if(data.contains("warning", Qt::CaseInsensitive))
            {
                item->setStatus("WARNING");
            }
            else if(data.contains("critical", Qt::CaseInsensitive))
            {
                item->setStatus("CRITICAL");
            }
            else if(data.contains("unknown", Qt::CaseInsensitive))
            {
                item->setStatus("UNKNOWN");
            }
            item->setHost(reg.cap(0).replace("host=","").toUpper());
        ...
        ...
        }
    }
    // Call beginResetModel() and endResetModel() to tell the model
    // and the view the data changed.
    beginResetModel();
    items_ = newItems;
    endResetModel();
    qDebug() << items_;
}
QHash<int, QByteArray> MDataModel::roleNames() const
{
    QHash<int, QByteArray> roles;
    roles[Host] = "host";
    roles[Service] = "service";
    roles[Status] = "status";
    roles[Duration] = "duration";
    roles[Info] = "info";
    // Add displayRole so that you can get what C++ views displays in QML
    // e.g Text { text: host + ' ' + status + ' (' + displayRole +')' }
    roles[Qt::DisplayRole] = "displayRole";
    return roles;
}

QML修复

delegate: Component
    {
        Rectangle
        {
            width: 250
            height: textItem.height
            Text {
                id: textItem 
                text: host + ' ' + status + ' (' + displayRole +')'
            }
        }
    }

此时，我的MDataModel.h和MDataModel.cpp看起来像这样:

MDataModel.h

class MDataModel : public QAbstractListModel
{
public:
    enum icingaRoles{
            host,
            service,
            status,
            duration,
            info
        };
    MDataModel(QObject *parent = 0);
    QHash<int, QByteArray> roleNames() const;
    void fillData(QNetworkReply *r);
    int rowCount(const QModelIndex &parent) const;
    QVariant data(const QModelIndex &index, int role) const;
private:
    QString dataAt(int offset) const;
    QList<MDataItem*> items_;
public:
    void prepareDataFinished(QNetworkReply *r);
};

MDataModel.cpp

MDataModel::MDataModel(QObject *parent) : QAbstractListModel(parent)
{
}
int MDataModel::rowCount(const QModelIndex & /* parent */) const
{
    return items_.count();
}

QVariant MDataModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
    {
        return QVariant();
    }
    if (role == Qt::DisplayRole)
    {
        switch(index.column()){
            case host:
                return items_.value(index.row())->host();
            case service:
                return items_.value(index.row())->service();
            case status:
                return items_.value(index.row())->status();
            case duration:
                return items_.value(index.row())->duration();
            case info:
                return items_.value(index.row())->info();
        }
    }
    return QVariant();
}

void MDataModel::prepareDataFinished(QNetworkReply *r)
{
    QList<MDataItem*> newItems;
    MDataItem *item = new MDataItem();
    QString data;
    while(r->canReadLine())
    {
        data = r->readLine();
        QRegExp reg;
        if(data.contains("statusbgwarning'><a href", Qt::CaseInsensitive) || data.contains("statusbgcritical'><a href", Qt::CaseInsensitive) || data.contains("statusbgunknown'><a href", Qt::CaseInsensitive))
        {
            item = new MDataItem();
            newItems.append(item);
            if(data.contains("warning", Qt::CaseInsensitive))
            {
                item->setStatus("WARNING");
            }
            else if(data.contains("critical", Qt::CaseInsensitive))
            {
                item->setStatus("CRITICAL");
            }
            else if(data.contains("unknown", Qt::CaseInsensitive))
            {
                item->setStatus("UNKNOWN");
            }
        ...
        ...
    }
    // Call beginResetModel() and endResetModel() to tell the model
    // and the view the data changed.
    beginResetModel();
    items_ = newItems;
    endResetModel();
}

QHash<int, QByteArray> MDataModel::roleNames() const
{
    QHash<int, QByteArray> roles;
    roles[host] = "host";
    roles[service] = "service";
    roles[status] = "status";
    roles[duration] = "duration";
    roles[info] = "info";
    return roles;
}