- Qt 6.8
- Qt Core
- C++ Classes
- QModelRoleData
- Qt 6.8.3 Reference Documentation

# QModelRoleData Class

The QModelRoleData class holds a role and the data associated to that role. More...

Header: | `#include <QModelRoleData>`
CMake: | `find_package(Qt6 REQUIRED COMPONENTS Core)` `target_link_libraries(mytarget PRIVATE Qt6::Core)`
qmake: | `QT += core`
Since: | Qt 6.0

- List of all members, including inherited members

## Public Functions

| QModelRoleData(int role)
void | clearData()
QVariant & | data()
const QVariant & | data() const
int | role() const
void | setData(T &&value)

## Detailed Description

QModelRoleData objects store an item role (which is a value from the Qt::ItemDataRole enumeration, or an arbitrary integer for a custom role) as well as the data associated with that role.

A QModelRoleData object is typically created by views or delegates, setting which role they want to fetch the data for. The object is then passed to models (see QAbstractItemModel::multiData()), which populate the data corresponding to the role stored. Finally, the view visualizes the data retrieved from the model.

See also Model/View Programming and QModelRoleDataSpan.

## Member Function Documentation

### `[explicit noexcept]` QModelRoleData::QModelRoleData(int role)

Constructs a QModelRoleData object for the given role.

See also Qt::ItemDataRole.

### `[noexcept]` void QModelRoleData::clearData()

Clears the data held by this object. Note that the role is unchanged; only the data is cleared.

See also data().

### `[constexpr noexcept]` QVariant &QModelRoleData::data()

Returns the data held by this object as a modifiable reference.

See also setData().

### `[constexpr noexcept]` const QVariant &QModelRoleData::data() const

Returns the data held by this object.

See also setData().

### `[constexpr noexcept]` int QModelRoleData::role() const

Returns the role held by this object.

See also Qt::ItemDataRole.

### `[constexpr noexcept(...)]` template <typename T> void QModelRoleData::setData(T &&value)

Sets the data held by this object to value. value must be of a datatype which can be stored in a QVariant.

Note: This function is noexcept when `noexcept(m_data.setValue(std::forward<T>(value)))` is `true`.

See also data(), clearData(), and Q_DECLARE_METATYPE.