The QModelIndex class is used to locate data in a data model. More...

#include <qabstractitemmodel.h>

Public Member Functions
constexpr	QModelIndex () noexcept

constexpr int	row () const noexcept

constexpr int	column () const noexcept

constexpr quintptr	internalId () const noexcept

void *	internalPointer () const noexcept

const void *	constInternalPointer () const noexcept

QModelIndex	parent () const

QModelIndex	sibling (int row, int column) const

QModelIndex	siblingAtColumn (int column) const

QModelIndex	siblingAtRow (int row) const

QVariant	data (int role=Qt::DisplayRole) const

void	multiData (QModelRoleDataSpan roleDataSpan) const

Qt::ItemFlags	flags () const

constexpr const QAbstractItemModel *	model () const noexcept

constexpr bool	isValid () const noexcept

constexpr bool	operator== (const QModelIndex &other) const noexcept

constexpr bool	operator!= (const QModelIndex &other) const noexcept

constexpr bool	operator< (const QModelIndex &other) const noexcept

Friends
class	QAbstractItemModel

Related Functions
(Note that these are not member functions.)
	QModelIndexList

Detailed Description

The QModelIndex class is used to locate data in a data model.

\inmodule QtCore

This class is used as an index into item models derived from QAbstractItemModel. The index is used by item views, delegates, and selection models to locate an item in the model.

New QModelIndex objects are created by the model using the QAbstractItemModel::createIndex() function. An invalid model index can be constructed with the QModelIndex constructor. Invalid indexes are often used as parent indexes when referring to top-level items in a model.

Model indexes refer to items in models, and contain all the information required to specify their locations in those models. Each index is located in a given row and column, and may have a parent index; use row(), column(), and parent() to obtain this information. Each top-level item in a model is represented by a model index that does not have a parent index - in this case, parent() will return an invalid model index, equivalent to an index constructed with the zero argument form of the QModelIndex() constructor.

To obtain a model index that refers to an existing item in a model, call QAbstractItemModel::index() with the required row and column values, and the model index of the parent. When referring to top-level items in a model, supply QModelIndex() as the parent index.

The model() function returns the model that the index references as a QAbstractItemModel. The child() function is used to examine items held under the index in the model. The sibling() function allows you to traverse items in the model on the same level as the index.

Note: Model indexes should be used immediately and then discarded. You should not rely on indexes to remain valid after calling model functions that change the structure of the model or delete items. If you need to keep a model index over time use a QPersistentModelIndex.

See also: {Model/View Programming}, QPersistentModelIndex, QAbstractItemModel

Definition at line 159 of file qabstractitemmodel.h.

Constructor & Destructor Documentation

◆ QModelIndex()

QModelIndex::QModelIndex ( )

inlineconstexprnoexcept

Creates a new empty model index. This type of model index is used to indicate that the position in the model is invalid.

See also: isValid(), QAbstractItemModel

Definition at line 163 of file qabstractitemmodel.h.

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Member Function Documentation

◆ column()

int QModelIndex::column ( ) const

inlineconstexprnoexcept

Returns the column this model index refers to.

Definition at line 166 of file qabstractitemmodel.h.

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◆ constInternalPointer()

const void * QModelIndex::constInternalPointer ( ) const

inlinenoexcept

Returns a {const void} {*} pointer used by the model to associate the index with the internal data structure.

See also: QAbstractItemModel::createIndex()

Definition at line 169 of file qabstractitemmodel.h.

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◆ data()

QVariant QModelIndex::data ( int role = Qt::DisplayRole ) const

inline

Returns the data for the given role for the item referred to by the index.

Definition at line 528 of file qabstractitemmodel.h.

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◆ flags()

Qt::ItemFlags QModelIndex::flags ( ) const

inline

Since: 4.2

Returns the flags for the item referred to by the index.

Definition at line 534 of file qabstractitemmodel.h.

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◆ internalId()

quintptr QModelIndex::internalId ( ) const

inlineconstexprnoexcept

Returns a {quintptr} used by the model to associate the index with the internal data structure.

See also: QAbstractItemModel::createIndex()

Definition at line 167 of file qabstractitemmodel.h.

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◆ internalPointer()

void * QModelIndex::internalPointer ( ) const

inlinenoexcept

Returns a {void} {*} pointer used by the model to associate the index with the internal data structure.

See also: QAbstractItemModel::createIndex()

Definition at line 168 of file qabstractitemmodel.h.

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◆ isValid()

bool QModelIndex::isValid ( ) const

inlineconstexprnoexcept

Returns {true} if this model index is valid; otherwise returns {false}.

A valid index belongs to a model, and has non-negative row and column numbers.

See also: model(), row(), column()

Definition at line 178 of file qabstractitemmodel.h.

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◆ model()

const QAbstractItemModel * QModelIndex::model ( ) const

inlineconstexprnoexcept

Returns a pointer to the model containing the item that this index refers to.

A const pointer to the model is returned because calls to non-const functions of the model might invalidate the model index and possibly crash your application.

Definition at line 177 of file qabstractitemmodel.h.

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◆ multiData()

void QModelIndex::multiData ( QModelRoleDataSpan roleDataSpan ) const

inline

Since: 6.0

Populates the given roleDataSpan for the item referred to by the index.

Definition at line 531 of file qabstractitemmodel.h.

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◆ operator!=()

bool QModelIndex::operator!= ( const QModelIndex & other ) const

inlineconstexprnoexcept

Returns {true} if this model index does not refer to the same location as the other model index; otherwise returns {false}.

Definition at line 181 of file qabstractitemmodel.h.

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◆ operator<()

bool QModelIndex::operator< ( const QModelIndex & other ) const

inlineconstexprnoexcept

Since: 4.1

Returns {true} if this model index is smaller than the other model index; otherwise returns {false}.

The less than calculation is not directly useful to developers - the way that indexes with different parents compare is not defined. This operator only exists so that the class can be used with QMap.

Definition at line 183 of file qabstractitemmodel.h.

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