在QML ListView中按角色对QAbstractListModel派生模型进行排序 [英] Sort a QAbstractListModel derived model by role in QML ListView

问题描述

我已经基于基础的QHash创建了QAbstractListModel派生模型.由于我需要在QML中使用该模型，因此无法使用Qt小部件和视图已集成的排序功能.

I've created a QAbstractListModel derived model based on an underlying QHash. Since I need to use the model in QML, I cannot make use of the sorting functionality Qt widgets and views have integrated.

我尝试使用QSortFilterProxyModel，但是它似乎不适用于我的模型.使模型在QML中正常工作还不够单调，现在我只能进行排序.

I tried using a QSortFilterProxyModel but it doesn't seem to work with my model. Getting the model to properly work in QML wasn't tedious enough, and now I am stuck on sorting.

任何建议都值得赞赏.

以下是模型来源:

typedef QHash<QString, uint> Data;

class NewModel : public QAbstractListModel {
    Q_OBJECT
    Q_PROPERTY(int count READ count NOTIFY countChanged)

public:
    NewModel(QObject * parent = 0) : QAbstractListModel(parent) {}

    enum Roles {WordRole = Qt::UserRole, CountRole};

    QHash<int, QByteArray> roleNames() const {
        QHash<int, QByteArray> roles;
        roles[WordRole] = "word";
        roles[CountRole] = "count";
        return roles;
    }

    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const {
        if (index.row() < 0 || index.row() >= m_data.size()) return QVariant();
        Data::const_iterator iter = m_data.constBegin() + index.row();

        switch (role) {
        case WordRole:
            return iter.key();
        case CountRole:
            return iter.value();
        } return QVariant();
    }

    int rowCount(const QModelIndex &parent) const {
        Q_UNUSED(parent)
        return m_data.size();
    }

    int count() const { return m_data.size(); }

public slots:
    void append(const QString &word) {
        bool alreadyThere = m_data.contains(word);
        if (alreadyThere) m_data[word]++;
        else m_data.insert(word, 1);

        Data::const_iterator iter = m_data.find(word);
        uint position = delta(iter);

        if (alreadyThere) {
            QModelIndex index = createIndex(position, 0);
            emit dataChanged(index, index);
        } else {
            beginInsertRows(QModelIndex(), position, position);
            endInsertRows();
            emit countChanged();
        }
    }

    void prepend(const QString &word) {
        if (m_data.contains(word)) m_data[word]++;
        else m_data.insert(word, 1);
    }

signals:
    void countChanged();

private:
    uint delta(Data::const_iterator i) {
        uint d = 0;
        while (i != m_data.constBegin()) { ++d; --i; }
        return d;
    }

    Data m_data;
};

此处正在尝试"对其进行排序:

Here is "trying" to sort it:

NewModel model;
QAbstractItemModel * pm = qobject_cast<QAbstractItemModel *>(&model);
QSortFilterProxyModel proxy;
proxy.setSourceModel(pm);
proxy.setSortRole(NewModel::WordRole);
proxy.setDynamicSortFilter(true);

A，代理充当模型，但是不对条目进行排序.

Alas, the proxy works as a model, but it doesn't sort the entries.

推荐答案

如果启用QSortFilterProxyModel :: setDynamicSortFilter(true)，则需要调用QSortFilterProxyModel :: sort(...)函数一次，以使代理知道哪种方式进行排序.

If you enable QSortFilterProxyModel::setDynamicSortFilter(true), you need to call QSortFilterProxyModel::sort(...) function once to let the proxy know which way to sort.

这样，只要更新模型，代理就会自动对所有内容再次进行排序.

With that, any time the model is updated the proxy will sort everything again just automatically.

proxy.setDynamicSortFilter(true);
proxy.sort(0);

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