- Qt 5.5
- Qt Core
- C++ Classes
- QIdentityProxyModel
- Qt 5.5.1 Reference Documentation

# QIdentityProxyModel Class

The QIdentityProxyModel class proxies its source model unmodified More...

Header: | #include <QIdentityProxyModel>
qmake: | QT += core
Since: | Qt 4.8
Inherits: | QAbstractProxyModel

- List of all members, including inherited members

## Public Functions

| QIdentityProxyModel(QObject * parent = 0)
| ~QIdentityProxyModel()

## Reimplemented Public Functions

virtual int | columnCount(const QModelIndex & parent = QModelIndex()) const
virtual bool | dropMimeData(const QMimeData * data, Qt::DropAction action, int row, int column, const QModelIndex & parent)
virtual QVariant | headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const
virtual QModelIndex | index(int row, int column, const QModelIndex & parent = QModelIndex()) const
virtual bool | insertColumns(int column, int count, const QModelIndex & parent = QModelIndex())
virtual bool | insertRows(int row, int count, const QModelIndex & parent = QModelIndex())
virtual QModelIndex | mapFromSource(const QModelIndex & sourceIndex) const
virtual QItemSelection | mapSelectionFromSource(const QItemSelection & selection) const
virtual QItemSelection | mapSelectionToSource(const QItemSelection & selection) const
virtual QModelIndex | mapToSource(const QModelIndex & proxyIndex) const
virtual QModelIndexList | match(const QModelIndex & start, int role, const QVariant & value, int hits = 1, Qt::MatchFlags flags = Qt::MatchFlags( Qt::MatchStartsWith | Qt::MatchWrap )) const
virtual QModelIndex | parent(const QModelIndex & child) const
virtual bool | removeColumns(int column, int count, const QModelIndex & parent = QModelIndex())
virtual bool | removeRows(int row, int count, const QModelIndex & parent = QModelIndex())
virtual int | rowCount(const QModelIndex & parent = QModelIndex()) const
virtual void | setSourceModel(QAbstractItemModel * newSourceModel)
virtual QModelIndex | sibling(int row, int column, const QModelIndex & idx) const

- 28 public functions inherited from QAbstractProxyModel
- 39 public functions inherited from QAbstractItemModel
- 31 public functions inherited from QObject

### Additional Inherited Members

- 1 property inherited from QAbstractProxyModel
- 1 property inherited from QObject
- 2 public slots inherited from QAbstractItemModel
- 1 public slot inherited from QObject
- 1 signal inherited from QAbstractProxyModel
- 18 signals inherited from QAbstractItemModel
- 2 signals inherited from QObject
- 11 static public members inherited from QObject
- 19 protected functions inherited from QAbstractItemModel
- 9 protected functions inherited from QObject
- 1 protected slot inherited from QAbstractProxyModel
- 1 protected slot inherited from QAbstractItemModel

## Detailed Description

The QIdentityProxyModel class proxies its source model unmodified

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 can not be modified.

    class DateFormatProxyModel : public QIdentityProxyModel
    {
      // ...

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

      QVariant data(const QModelIndex &index, int role) const
      {
        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 QAbstractProxyModel, Model/View Programming, and QAbstractItemModel.

## Member Function Documentation

### QIdentityProxyModel::QIdentityProxyModel(QObject * parent = 0)

Constructs an identity model with the given parent.

### QIdentityProxyModel::~QIdentityProxyModel()

Destroys this identity model.

### `[virtual]` int QIdentityProxyModel::columnCount(const QModelIndex & parent = QModelIndex()) const

Reimplemented from QAbstractItemModel::columnCount().

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

Reimplemented from QAbstractItemModel::dropMimeData().

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

Reimplemented from QAbstractItemModel::headerData().

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

Reimplemented from QAbstractItemModel::index().

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

Reimplemented from QAbstractItemModel::insertColumns().

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

Reimplemented from QAbstractItemModel::insertRows().

### `[virtual]` QModelIndex QIdentityProxyModel::mapFromSource(const QModelIndex & sourceIndex) const

Reimplemented from QAbstractProxyModel::mapFromSource().

### `[virtual]` QItemSelection QIdentityProxyModel::mapSelectionFromSource(const QItemSelection & selection) const

Reimplemented from QAbstractProxyModel::mapSelectionFromSource().

### `[virtual]` QItemSelection QIdentityProxyModel::mapSelectionToSource(const QItemSelection & selection) const

Reimplemented from QAbstractProxyModel::mapSelectionToSource().

### `[virtual]` QModelIndex QIdentityProxyModel::mapToSource(const QModelIndex & proxyIndex) const

Reimplemented from QAbstractProxyModel::mapToSource().

### `[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

Reimplemented from QAbstractItemModel::match().

### `[virtual]` QModelIndex QIdentityProxyModel::parent(const QModelIndex & child) const

Reimplemented from QAbstractItemModel::parent().

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

Reimplemented from QAbstractItemModel::removeColumns().

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

Reimplemented from QAbstractItemModel::removeRows().

### `[virtual]` int QIdentityProxyModel::rowCount(const QModelIndex & parent = QModelIndex()) const

Reimplemented from QAbstractItemModel::rowCount().

### `[virtual]` void QIdentityProxyModel::setSourceModel(QAbstractItemModel * newSourceModel)

Reimplemented from QAbstractProxyModel::setSourceModel().

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

Reimplemented from QAbstractItemModel::sibling().