QIdentityProxyModel Class

QIdentityProxyModel can be used to forward the structure of a source model exactly, with no sorting, filtering or other transformation. This is similar in concept to an identity matrix where A.I = A.

Because it does no sorting or filtering, this class is most suitable to proxy models which transform the data() of the source model. For example, a proxy model could be created to define the font used, or the background colour, or the tooltip etc. This removes the need to implement all data handling in the same class that creates the structure of the model, and can also be used to create re-usable components.

This also provides a way to change the data in the case where a source model is supplied by a third party which cannot be modified.

class DateFormatProxyModel : public QIdentityProxyModel
{
  // ...

  void setDateFormatString(const QString &formatString)
  {
    m_formatString = formatString;
  }

  QVariant data(const QModelIndex &index, int role) const override
  {
    if (role != Qt::DisplayRole)
      return QIdentityProxyModel::data(index, role);

    const QDateTime dateTime = sourceModel()->data(SourceClass::DateRole).toDateTime();

    return dateTime.toString(m_formatString);
  }

private:
  QString m_formatString;
};

See Also▲

[explicit] QIdentityProxyModel::QIdentityProxyModel(QObject *parent = nullptr)▲

[virtual] QIdentityProxyModel::~QIdentityProxyModel()▲

[override virtual] int QIdentityProxyModel::columnCount(const QModelIndex &parent = QModelIndex()) const▲

[override virtual] bool QIdentityProxyModel::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent)▲

[override virtual] QVariant QIdentityProxyModel::headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const▲

[override virtual] QModelIndex QIdentityProxyModel::index(int row, int column, const QModelIndex &parent = QModelIndex()) const▲

[override virtual] bool QIdentityProxyModel::insertColumns(int column, int count, const QModelIndex &parent = QModelIndex())▲

[override virtual] bool QIdentityProxyModel::insertRows(int row, int count, const QModelIndex &parent = QModelIndex())▲

[override virtual] QModelIndex QIdentityProxyModel::mapFromSource(const QModelIndex &sourceIndex) const▲

[override virtual] QItemSelection QIdentityProxyModel::mapSelectionFromSource(const QItemSelection &selection) const▲

[override virtual] QItemSelection QIdentityProxyModel::mapSelectionToSource(const QItemSelection &selection) const▲

[override virtual] QModelIndex QIdentityProxyModel::mapToSource(const QModelIndex &proxyIndex) const▲

[override virtual] QModelIndexList QIdentityProxyModel::match(const QModelIndex &start, int role, const QVariant &value, int hits = 1, Qt::MatchFlags flags = Qt::MatchFlags(Qt::MatchStartsWith|Qt::MatchWrap)) const▲

[override virtual, since 5.15] bool QIdentityProxyModel::moveColumns(const QModelIndex &sourceParent, int sourceColumn, int count, const QModelIndex &destinationParent, int destinationChild)▲

[override virtual, since 5.15] bool QIdentityProxyModel::moveRows(const QModelIndex &sourceParent, int sourceRow, int count, const QModelIndex &destinationParent, int destinationChild)▲

[override virtual] QModelIndex QIdentityProxyModel::parent(const QModelIndex &child) const▲

[override virtual] bool QIdentityProxyModel::removeColumns(int column, int count, const QModelIndex &parent = QModelIndex())▲

[override virtual] bool QIdentityProxyModel::removeRows(int row, int count, const QModelIndex &parent = QModelIndex())▲

[override virtual] int QIdentityProxyModel::rowCount(const QModelIndex &parent = QModelIndex()) const▲

[override virtual] void QIdentityProxyModel::setSourceModel(QAbstractItemModel *newSourceModel)▲

[override virtual] QModelIndex QIdentityProxyModel::sibling(int row, int column, const QModelIndex &idx) const▲