The QSqlQueryModel class provides a read-only data model for SQL result sets. More...

Inheritance diagram for QSqlQueryModel:

Public Methods
	QSqlQueryModel (QObject *parent=nullptr)

virtual	~QSqlQueryModel ()

bool	canFetchMore (const QModelIndex &parent=QModelIndex ()) const override

virtual void	clear ()

int	columnCount (const QModelIndex &index=QModelIndex ()) const override

QVariant	data (const QModelIndex &item, int role=Qt::DisplayRole) const override

void	fetchMore (const QModelIndex &parent=QModelIndex ()) override

QVariant	headerData (int section, Qt::Orientation orientation, int role=Qt::DisplayRole) const override

bool	insertColumns (int column, int count, const QModelIndex &parent=QModelIndex ()) override

QSqlError	lastError () const

QSqlQuery	query () const

QSqlRecord	record () const

QSqlRecord	record (int row) const

bool	removeColumns (int column, int count, const QModelIndex &parent=QModelIndex ()) override

int	rowCount (const QModelIndex &index=QModelIndex ()) const override

bool	setHeaderData (int section, Qt::Orientation orientation, const QVariant &value, int role=Qt::EditRole) override

void	setQuery (const QSqlQuery &query)

void	setQuery (const QString &query, const QSqlDatabase &db=QSqlDatabase ())

Public Methods inherited from QAbstractTableModel
	QAbstractTableModel (QObject *parent=nullptr)

	~QAbstractTableModel ()

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

Qt::ItemFlags	flags (const QModelIndex &index) const override

QModelIndex	index (int row, int column, const QModelIndex &parent=QModelIndex ()) const override

QObject *	parent () const

QModelIndex	sibling (int row, int column, const QModelIndex &index) const override

Public Methods inherited from QAbstractItemModel
	QAbstractItemModel (QObject *parent=nullptr)

virtual	~QAbstractItemModel ()

virtual QModelIndex	buddy (const QModelIndex &index) const

virtual bool	canDropMimeData (const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) const

bool	hasIndex (int row, int column, const QModelIndex &parent=QModelIndex ()) const

bool	insertColumn (int column, const QModelIndex &parent=QModelIndex ())

bool	insertRow (int row, const QModelIndex &parent=QModelIndex ())

virtual bool	insertRows (int row, int count, const QModelIndex &parent=QModelIndex ())

virtual QMap< int, QVariant >	itemData (const QModelIndex &index) 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 QMimeData *	mimeData (const QModelIndexList &indexes) const

virtual QStringList	mimeTypes () const

bool	moveColumn (const QModelIndex &sourceParent, int sourceColumn, const QModelIndex &destinationParent, int destinationChild)

virtual bool	moveColumns (const QModelIndex &sourceParent, int sourceColumn, int count, const QModelIndex &destinationParent, int destinationChild)

bool	moveRow (const QModelIndex &sourceParent, int sourceRow, const QModelIndex &destinationParent, int destinationChild)

virtual bool	moveRows (const QModelIndex &sourceParent, int sourceRow, int count, const QModelIndex &destinationParent, int destinationChild)

QObject *	parent () const

bool	removeColumn (int column, const QModelIndex &parent=QModelIndex ())

bool	removeRow (int row, const QModelIndex &parent=QModelIndex ())

virtual bool	removeRows (int row, int count, const QModelIndex &parent=QModelIndex ())

virtual QMultiHash< int, QString >	roleNames () const

virtual bool	setData (const QModelIndex &index, const QVariant &value, int role=Qt::EditRole)

virtual bool	setItemData (const QModelIndex &index, const QMap< int, QVariant > &roles)

virtual void	sort (int column, Qt::SortOrder order=Qt::AscendingOrder)

virtual QSize	span (const QModelIndex &index) const

virtual Qt::DropActions	supportedDragActions () const

virtual Qt::DropActions	supportedDropActions () const

Public Methods inherited from QObject
	QObject (QObject *parent=nullptr)

	~QObject ()

bool	blockSignals (bool block)

const QList< QObject * > &	children () const

bool	connect (const QObject *sender, const QString &signalMethod, const QString &location, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	connect (const QObject *sender, const QString &signalMethod, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

bool	disconnect (const QObject *receiver, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod, const QString &location, const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

bool	disconnect (const QString &signalMethod=QString (), const QObject *receiver=nullptr, const QString &slotMethod=QString ()) const

void	dumpObjectInfo ()

void	dumpObjectTree ()

QList< QString >	dynamicPropertyNames () const

virtual bool	event (QEvent *event)

virtual bool	eventFilter (QObject watched, QEvent event)

template<typename T >
T	findChild (const QString &childName=QString ()) const

template<class T >
QList< T >	findChildren (const QRegularExpression &regExp, Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

template<class T >
QList< T >	findChildren (const QString &childName=QString (), Qt::FindChildOptions options=Qt::FindChildrenRecursively) const

bool	inherits (const QString &className) const

void	installEventFilter (QObject *filterObj)

bool	isWidgetType () const

bool	isWindowType () const

void	killTimer (int id)

const QMetaObject *	metaObject () const

void	moveToThread (QThread *targetThread)

QString	objectName () const

QObject *	parent () const

template<class T = QVariant>
T	property (const QString &name) const

void	removeEventFilter (QObject *obj)

void	setObjectName (const QString &name)

void	setParent (QObject *parent)

bool	setProperty (const QString &name, const QVariant &value)

bool	signalsBlocked () const

int	startTimer (int interval, Qt::TimerType timerType=Qt::CoarseTimer)

QThread *	thread () const

Protected Methods
virtual QModelIndex	indexInQuery (const QModelIndex &item) const

virtual void	queryChange ()

void	setLastError (const QSqlError &error)

Protected Methods inherited from QAbstractItemModel
void	beginInsertColumns (const QModelIndex &parent, int first, int last)

void	beginInsertRows (const QModelIndex &parent, int first, int last)

bool	beginMoveColumns (const QModelIndex &sourceParent, int sourceFirst, int sourceLast, const QModelIndex &destinationParent, int destinationColumn)

bool	beginMoveRows (const QModelIndex &sourceParent, int sourceFirst, int sourceLast, const QModelIndex &destinationParent, int destinationRow)

void	beginRemoveColumns (const QModelIndex &parent, int first, int last)

void	beginRemoveRows (const QModelIndex &parent, int first, int last)

void	beginResetModel ()

void	changePersistentIndex (const QModelIndex &from, const QModelIndex &to)

void	changePersistentIndexList (const QModelIndexList &from, const QModelIndexList &to)

QModelIndex	createIndex (int row, int column, quintptr id) const

QModelIndex	createIndex (int row, int column, void *data=nullptr) const

void	endInsertColumns ()

void	endInsertRows ()

void	endMoveColumns ()

void	endMoveRows ()

void	endRemoveColumns ()

void	endRemoveRows ()

void	endResetModel ()

QModelIndexList	persistentIndexList () const

Protected Methods inherited from QObject
virtual void	childEvent (QChildEvent *event)

virtual void	connectNotify (const QMetaMethod &signalMethod) const

virtual void	customEvent (QEvent *event)

virtual void	disconnectNotify (const QMetaMethod &signalMethod) const

bool	isSignalConnected (const QMetaMethod &signalMethod) const

int	receivers (const QString &signal) const

QObject *	sender () const

int	senderSignalIndex () const

virtual void	timerEvent (QTimerEvent *event)

Additional Inherited Members
Public Signals inherited from QAbstractItemModel
void	columnsAboutToBeInserted (const QModelIndex &parent, int first, int last)

void	columnsAboutToBeMoved (const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationColumn)

void	columnsAboutToBeRemoved (const QModelIndex &parent, int first, int last)

void	columnsInserted (const QModelIndex &parent, int first, int last)

void	columnsMoved (const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationColumn)

void	columnsRemoved (const QModelIndex &parent, int first, int last)

void	dataChanged (const QModelIndex &topLeft, const QModelIndex &bottomRight, const QVector< int > &roles=QVector< int >())

void	headerDataChanged (Qt::Orientation orientation, int first, int last)

void	layoutAboutToBeChanged (const QList< QPersistentModelIndex > &parents=QList< QPersistentModelIndex >(), QAbstractItemModel::LayoutChangeHint hint=QAbstractItemModel::NoLayoutChangeHint)

void	layoutChanged (const QList< QPersistentModelIndex > &parents=QList< QPersistentModelIndex >(), QAbstractItemModel::LayoutChangeHint hint=QAbstractItemModel::NoLayoutChangeHint)

void	modelAboutToBeReset ()

void	modelReset ()

void	rowsAboutToBeInserted (const QModelIndex &parent, int first, int last)

void	rowsAboutToBeMoved (const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationRow)

void	rowsAboutToBeRemoved (const QModelIndex &parent, int first, int last)

void	rowsInserted (const QModelIndex &parent, int first, int last)

void	rowsMoved (const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationRow)

void	rowsRemoved (const QModelIndex &parent, int first, int last)

Public Signals inherited from QObject
void	destroyed (QObject *obj=nullptr)

void	objectNameChanged (const QString &objectName)

Public Slots inherited from QAbstractItemModel
virtual void	revert ()

virtual bool	submit ()

Public Slots inherited from QObject
void	deleteLater ()

Static Public Methods inherited from QObject
static bool	connect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

static bool	connect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection, const QString &location=QString ())

static bool	connect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod, Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...), Qt::ConnectionType type=Qt::AutoConnection)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	connect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotLambda, Qt::ConnectionType type=Qt::AutoConnection)

static bool	disconnect (const QObject sender, const QMetaMethod &signalMethod, const QObject receiver, const QMetaMethod &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, const QString &signalMethod, const QString &location, const QObject receiver, const QString &slotMethod)

static bool	disconnect (const QObject sender, std::nullptr_t, const QObject receiver, std::nullptr_t)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class SlotClass , class... SlotArgs, class SlotReturn >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver receiver, SlotReturn (SlotClass::slotMethod)(SlotArgs...))

template<class Sender , class SignalClass , class... SignalArgs, class Receiver >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, std::nullptr_t slotMethod=nullptr)

template<class Sender , class SignalClass , class... SignalArgs, class Receiver , class T >
static bool	disconnect (const Sender sender, void (SignalClass::signalMethod)(SignalArgs...), const Receiver *receiver, T slotMethod)

static QMetaObject &	staticMetaObject ()

static QString	tr (const char text, const char comment=nullptr, std::optional< int > numArg=std::optional< int >())

Protected Slots inherited from QAbstractItemModel
void	resetInternalData ()

Properties inherited from QObject
	objectName

Related Functions inherited from QObject
T	qobject_cast (QObject *object)

	QObjectList

Detailed Description

The QSqlQueryModel class provides a read only data model for SQL result sets. This class is a high level interface for executing SQL statements and traversing the result set. It is built on top of the lower level QSqlQuery and can be used to provide data to view classes such as QTableView.

If the database does not return the number of selected rows in a query, the model will fetch rows incrementally. Refer to fetchMore() for more information.

Example

In the following code the setQuery() is called on the model and then the column headers are configured.

QSqlQueryModel *model = new QSqlQueryModel;
model->setQuery("SELECT name, salary FROM employee");
 
model->setHeaderData(0, Qt::Horizontal, tr("Name"));
model->setHeaderData(1, Qt::Horizontal, tr("Salary"));
 
QTableView *view = new QTableView;
view->setModel(model);
view->show();

QSqlQueryModel can also be used to access a database without binding it to a view. The code shown below extracts the salary field from record 4 in the result set.

QSqlQueryModel model;
model.setQuery("SELECT * FROM employee");
 
int salaryA = model.record(4).value("salary").toInt();
int salaryB = model.data(model.index(4, 2)).toInt();

Inheriting

The QSqlQueryModel is read only. In order to write to the database using this model you will need to inherit from this class and override setData() and flags().

Another option is to use QSqlTableModel which provides a read /write model based on a single database table.

See also: QSqlTableModel, QSqlRelationalTableModel, QSqlQuery, Model/View Architecture

Constructor & Destructor Documentation

QSqlQueryModel::QSqlQueryModel ( QObject * parent = nullptr )

explicit

Creates an empty QSqlQueryModel with the given parent.

QSqlQueryModel::~QSqlQueryModel ( )

virtual

Destroys the object and frees any allocated resources.

See also: clear()

Method Documentation

bool QSqlQueryModel::canFetchMore ( const QModelIndex & parent = QModelIndex() ) const

overridevirtual

The parent should always be an invalid QModelIndex. Returns true if it is possible to read more rows from the database. This only affects databases that do not report back the size of a query.

See also: fetchMore(), QSqlDriver::hasFeature()

Reimplemented from QAbstractItemModel::canFetchMore()

void QSqlQueryModel::clear ( )

virtual

Clears the model and releases any acquired resource.

Reimplemented in QSqlRelationalTableModel::clear(), QSqlTableModel::clear()

int QSqlQueryModel::columnCount ( const QModelIndex & index = QModelIndex() ) const

overridevirtual

Implements QAbstractItemModel::columnCount()

QVariant QSqlQueryModel::data	(	const QModelIndex &	item,
		int	role = `Qt::DisplayRole`
	)		const

overridevirtual

Returns the value for the specified item and role. If item is out of bounds or if an error occurred, an invalid QVariant is returned.

See also: lastError()

Implements QAbstractItemModel::data()

Reimplemented in QSqlRelationalTableModel::data(), QSqlTableModel::data()

void QSqlQueryModel::fetchMore ( const QModelIndex & parent = QModelIndex() )

overridevirtual

The parent should always be an invalid QModelIndex. Fetches more rows from a database. This only affects databases that do not report back the size of a query (see QSqlDriver::hasFeature()). The following example shows how to force fetching of the entire result set.

while (myModel->canFetchMore()) {
   myModel->fetchMore();
}

See also: canFetchMore()

Reimplemented from QAbstractItemModel::fetchMore()

QVariant QSqlQueryModel::headerData	(	int	section,
		Qt::Orientation	orientation,
		int	role = `Qt::DisplayRole`
	)		const

overridevirtual

Returns the header data for the given role in the section of the header with the specified orientation.

See also: setHeaderData()

Reimplemented from QAbstractItemModel::headerData()

Reimplemented in QSqlTableModel::headerData()

QModelIndex QSqlQueryModel::indexInQuery ( const QModelIndex & item ) const

protectedvirtual

Returns the index of the value in the database result set for the given item in the model. The return value is identical to item if no columns or rows have been inserted, removed, or moved around. Returns an invalid model index if item is out of bounds or if item does not point to a value in the result set.

See also: QSqlTableModel::indexInQuery(), insertColumns(), removeColumns()

Reimplemented in QSqlTableModel::indexInQuery()

bool QSqlQueryModel::insertColumns	(	int	column,
		int	count,
		const QModelIndex &	parent = `QModelIndex()`
	)

overridevirtual

Inserts count columns into the model at position column. The parent object must always be an invalid QModelIndex, since the model does not support parent-child relationships. Returns true if column is within bounds, otherwise returns false. By default inserted columns are empty. To fill them with data, reimplement data() and handle any inserted column separately.

QVariant MyModel::data(const QModelIndex &item, int role) const
{
    if (item.column() == m_specialColumnNo) {
        // handle column separately
    }
 
    return QSqlQueryModel::data(item, role);
}

See also: removeColumns()

Reimplemented from QAbstractItemModel::insertColumns()

QSqlError QSqlQueryModel::lastError ( ) const

Returns information about the last error that occurred on the database.

See also: setLastError(), query()

QSqlQuery QSqlQueryModel::query ( ) const

Returns the QSqlQuery associated with this model.

See also: setQuery()

void QSqlQueryModel::queryChange ( )

protectedvirtual

This method is called whenever the query changes. The default implementation does nothing. Use query() to retrieve the new query.

See also: query(), setQuery()

QSqlRecord QSqlQueryModel::record ( ) const

Returns an empty record containing information about the fields of the current query. If the model is not initialized, an empty record will be returned.

See also: QSqlRecord::isEmpty()

QSqlRecord QSqlQueryModel::record ( int row ) const

Returns the record containing information about the fields of the current query. If row is the index of a valid row, the record will be populated with values from that row. If the model is not initialized, an empty record will be returned.

See also: QSqlRecord::isEmpty()

bool QSqlQueryModel::removeColumns	(	int	column,
		int	count,
		const QModelIndex &	parent = `QModelIndex()`
	)

overridevirtual

Removes count columns from the model starting from position column. The parent object must always be an invalid QModelIndex, since the model does not support parent-child relationships. Removing columns effectively hides them. It does not affect the underlying QSqlQuery.

Returns true if the columns were removed, otherwise returns false.

Reimplemented from QAbstractItemModel::removeColumns()

Reimplemented in QSqlTableModel::removeColumns(), QSqlRelationalTableModel::removeColumns()

int QSqlQueryModel::rowCount ( const QModelIndex & index = QModelIndex() ) const

overridevirtual

If the database supports returning the size of a query the number of rows of the current query is returned. Otherwise, returns the number of rows currently cached on the client. The index should always be an invalid QModelIndex.

See also: canFetchMore(), QSqlDriver::hasFeature()

Implements QAbstractItemModel::rowCount()

Reimplemented in QSqlTableModel::rowCount()

bool QSqlQueryModel::setHeaderData	(	int	section,
		Qt::Orientation	orientation,
		const QVariant &	value,
		int	role = `Qt::EditRole`
	)

overridevirtual

Sets the caption for a horizontal header for the specified role to value. This is useful if the model is used to display data in a view (e.g., QTableView). Returns true if orientation is Qt::Horizontal and the section refers to a valid section, otherwise returns false. This method can not be used to modify values in the database since the model is read only.

See also: headerData(), data()

Reimplemented from QAbstractItemModel::setHeaderData()

void QSqlQueryModel::setLastError ( const QSqlError & error )

protected

Protected method which allows derived classes to set the value of the last error that occurred on the database to error.

See also: lastError()

void QSqlQueryModel::setQuery ( const QSqlQuery & query )

Resets the model and sets the data provider to be the given query. The query must be active and must not be isForwardOnly(). Calling lastError() can be used to retrieve verbose information if there was an error setting the query. Calling setQuery() will remove any inserted columns.

See also: query(), QSqlQuery::isActive(), QSqlQuery::setForwardOnly(), lastError()

void QSqlQueryModel::setQuery	(	const QString &	query,
		const QSqlDatabase &	db = `QSqlDatabase()`
	)

Executes the query for the given database connection db. If no database or an invalid database is specified, the default connection is used. Calling lastError() can be used to retrieve verbose information if there was an error setting the query.

QSqlQueryModel model;
model.setQuery("select * from MyTable");
 
if (model.lastError().isValid()) {
   qDebug() << model.lastError();
}

See also: query(), queryChange(), lastError()

Public Methods

Protected Methods

Additional Inherited Members

Detailed Description

Example

Inheriting

Constructor & Destructor Documentation

Method Documentation