The QSparqlResult class provides an abstract interface for accessing the results of an executed QSparqlQuery. More...

Inherits QObject.

Inherited by EndpointResult, QSparqlNullResult, QTrackerDirectResult, QTrackerResult, and QVirtuosoResult.

Public Types
enum	Feature { QuerySize, ForwardOnly, Sync }

Signals
void	dataReady (int totalCount)

void	finished ()

Public Member Functions
virtual	~QSparqlResult ()

int	pos () const

virtual bool	setPos (int pos)

virtual bool	next ()

virtual bool	previous ()

virtual bool	first ()

virtual bool	last ()

virtual int	size () const

bool	isValid () const

virtual QSparqlResultRow	current () const =0

virtual QSparqlBinding	binding (int i) const =0

virtual QVariant	value (int i) const =0

virtual QString	stringValue (int i) const

bool	boolValue () const

virtual void	waitForFinished ()

virtual bool	isFinished () const

bool	hasError () const

QSparqlError	lastError () const

QString	query () const

QSparqlQuery::StatementType	statementType () const
	Returns the statement type of this QSparqlResult object.

bool	isTable () const

bool	isGraph () const

bool	isBool () const

virtual bool	hasFeature (QSparqlResult::Feature feature) const

Protected Member Functions
	QSparqlResult ()

void	setQuery (const QString &query)

void	setStatementType (QSparqlQuery::StatementType type)
	Sets the statement type of this QSparqlResult object.

void	setLastError (const QSparqlError &e)

void	setBoolValue (bool v)

void	updatePos (int pos)

Friends
class	QSparqlResultPrivate

class	QSparqlConnection

class	QSparqlConnectionPrivate

Detailed Description

The QSparqlResult class provides an abstract interface for accessing the results of an executed QSparqlQuery.

When QSparqlConnection::exec() is called, it asynchronously begins the execution of the given query. The returned result is in an unfinished state so that isFinished() returns false. When the execution finished, QSparqlResult emits the finished() signal and sets itself to finished state.

Initially, QSparqlResult is positioned on an invalid position. It must be navigated to a valid position (so that isValid() returns true) before values can be retrieved.

Navigating the result is performed with the following functions:

Retrieving the data is performed with the following functions:

Member Enumeration Documentation

◆ Feature

enum QSparqlResult::Feature

This enum contains a list of features a QSparqlResult might support. Use hasFeature() to query whether a feature is supported or not. The supported features depend on the driver and whether the result was obtained via QSparqlConnection::exec() or QSparqlConnection::syncExec().

Enumerator

QuerySize

Whether the QSparqlResult can report the number of results of the query.

ForwardOnly

Whether the result can only be navigated forward (i.e., using QSparqlResult::next()).

Sync

Whether the result is natively synchronous (was retrieved via QSparqlConnection::syncExec() of natively synchronous connection). In this case, QSparqlResult::next() will fetch the next result synchronously.

See also: hasFeature()

Constructor & Destructor Documentation

◆ ~QSparqlResult()

QSparqlResult::~QSparqlResult ( )

virtual

Destroys the object and frees any allocated resources.

◆ QSparqlResult()

QSparqlResult::QSparqlResult ( )

protected

Creates a QSparqlResult. The result is empty, positioned at "before first row" and unfinished.

Member Function Documentation

◆ binding()

QSparqlBinding QSparqlResult::binding ( int index ) const

pure virtual

Returns the binding index in the current result row.

The bindings are numbered from left to right using the text of the SELECT statement. The indexes start from 0.

An invalid QSparqlBinding is returned if binding index does not exist, if the query is inactive, or if the query is positioned on an invalid result row.

See also: value() previous() next() first() last() setPos() isValid()

◆ boolValue()

bool QSparqlResult::boolValue ( ) const

Returns the boolean result of an ASK query.

Note that this should only be used when isFinished() is true.

See also: isBool() setBoolValue()

◆ current()

QSparqlResultRow QSparqlResult::current ( ) const

pure virtual

Returns a QSparqlResultRow containing the binding values for the current row. If the result points to a valid row (isValid() returns true), the result row is populated. An empty result row is returned when there is no result at the current position.

To retrieve just the values from a query, value() should be used since its index-based lookup is faster. Use QSparqlResultRow::binding() to retrieve the value along with meta data, such as the data type URI or language tag for literals.

See also: value() binding() pos() setPos()

◆ dataReady

void QSparqlResult::dataReady ( int totalRows )

signal

This signal is emitted when a query has fetched data. The totalRows is the row count of the data set after the new data has arrived.

◆ finished

void QSparqlResult::finished ( )

signal

This signal is emitted when the QSparqlResult has finished retrieving its data or when there was an error.

◆ first()

bool QSparqlResult::first ( )

virtual

Retrieves the first row in the result, if available, and positions the query on the retrieved row. Returns true if successful. If unsuccessful the query position is set to an invalid position and false is returned.

See also: next() previous() last() setPos() pos() isFinished() isValid()

◆ hasError()

bool QSparqlResult::hasError ( ) const

Returns true if the query has finished and there is an error associated with the result.

See also: setLastError() lastError() isFinished()

◆ hasFeature()

bool QSparqlResult::hasFeature ( QSparqlResult::Feature feature ) const

virtual

Returns true if the QSparqlResult supports feature feature; otherwise returns false.

◆ isBool()

bool QSparqlResult::isBool ( ) const

Returns true if the statement is an ASK query returning a boolean value

See also: isTable() isGraph() boolValue()

◆ isFinished()

bool QSparqlResult::isFinished ( ) const

virtual

Returns true if the pending query has finished processing and the result has been received. If this function returns true, the hasError() and lastError() methods should return valid information.

The usage of this function differs depending on the driver, and method of execution used. For asynchronous queries the results will be available once the finished() signal has been emitted, or waitForFinished() has been called. For synchronous execution, where the driver supports QSparqlConnection::SyncExec, the value of isFinished() will be false until all the results have been retrieved using next().

E.g For a synchronous result

    QSparqlResult *result = connection.syncExec(query);
    // result->isFinished() will be false
    while(result->next())
        do something
    // result->isFinished() will now be true

And for asynchronous execution

    QSparqlResult *result = connection.exec(query);
    result->waitForFinished();
    result->isFinished(); // will be true

Note that this function only changes state if you call waitForFinished(), or if an external event happens, which in general only happens if you return to the event loop execution.

See also: waitForFinished() lastError() error()

◆ isGraph()

bool QSparqlResult::isGraph ( ) const

Returns true if the statement is a CONSTRUCT or DESCRIBE query returning a graph. Each QSparqlResultRow in a graph result hasError three QSParqlBinding values, named 's', 'p' and 'o' corresponding to triples with Subject, Predicate and Object values

See also: isTable() isBool()

◆ isTable()

bool QSparqlResult::isTable ( ) const

Returns true if this QSparqlResult object represents results that are in the tabular format, e.g., the results of a SELECT query.

◆ isValid()

bool QSparqlResult::isValid ( ) const

Returns true if the result is positioned on a valid row (that is, the result is not positioned before the first or after the last row); otherwise returns false.

See also: pos()

◆ last()

bool QSparqlResult::last ( )

virtual

Retrieves the last row in the result, if available, and positions the query on the retrieved row. Note that the result must be in the finished state before calling this function or it will do nothing and return false. Returns true if successful. If unsuccessful the query position is set to an invalid position and false is returned.

See also: next() previous() first() setPos() pos() isFinished() isValid()

◆ lastError()

QSparqlError QSparqlResult::lastError ( ) const

Once the query has finished, returns the last error associated with the result

See also: setLastError() hasError() isFinished()

◆ next()

bool QSparqlResult::next ( )

virtual

Retrieves the next row in the result, if available, and positions the query on the retrieved row. Note that the isTable() or isGraph() must return true before calling this function or it will do nothing and return false.

The following rules apply:

If the result is currently located before the first row, e.g. immediately after a query is executed, an attempt is made to retrieve the first row.
If the result is currently located after the last row, there is no change and false is returned.
If the result is located somewhere in the middle, an attempt is made to retrieve the next row.

If the row could not be retrieved, the result is positioned after the last row and false is returned. If the row is successfully retrieved, true is returned.

See also: previous() first() last() setPos() pos() isFinished() isValid()

◆ pos()

int QSparqlResult::pos ( ) const

Returns the current internal position of the query. The first row is at position zero. If the position is invalid, the function returns QSparql::BeforeFirstRow or QSparql::AfterLastRow, which are special negative values.

See also: previous() next() first() last()

◆ previous()

bool QSparqlResult::previous ( )

virtual

Retrieves the previous row in the result, if available, and positions the query on the retrieved row.

The following rules apply:

If the result is currently located before the first row, there is no change and false is returned.
If the result is currently located after the last row, an attempt is made to retrieve the last row.
If the result is somewhere in the middle, an attempt is made to retrieve the previous row.

If the row could not be retrieved, the result is positioned before the first row and false is returned. If the row is successfully retrieved, true is returned.

See also: next() first() last() setPos() pos() isFinished() isValid()

◆ query()

QString QSparqlResult::query ( ) const

Returns the query which was executed for creating this QSparqlResult. Useful for debugging purposes.

◆ setBoolValue()

void QSparqlResult::setBoolValue ( bool v )

protected

Set the boolean result of an ASK query

See also: isBool() boolValue()

◆ setLastError()

void QSparqlResult::setLastError ( const QSparqlError & error )

protected

This function is provided for derived classes to set the last error to error.

See also: lastError() hasError()

◆ setPos()

bool QSparqlResult::setPos ( int pos )

virtual

This function is provided to set the internal (zero-based) row position to index. If the index is within the range of result rows retrieved the function returns true, otherwise false.

See also: pos()

◆ setQuery()

void QSparqlResult::setQuery ( const QString & query )

protected

Sets the information about the query whose results this QSparqlResult object represents.

◆ size()

int QSparqlResult::size ( ) const

virtual

Returns the size of the result (number of rows returned).

A return value of -1 is used if the result does not support QuerySize information, or if the query has not yet finished (isFinished() returns false)

See also: isFinished() QSparqlResult::hasFeature()

◆ stringValue()

QString QSparqlResult::stringValue ( int i ) const

virtual

Returns the value on column column on the current result row as a string. This function ignores the type of the data.

An empty QString is returned if column column does not exist, or if the result is positioned on an invalid result row.

See also: binding() value() current()

◆ updatePos()

void QSparqlResult::updatePos ( int index )

protected

This function is provided for derived classes which handle position tracking themselves, allowing them to record the current position in the results

◆ value()

QVariant QSparqlResult::value ( int index ) const

pure virtual

Returns the value of binding index in the current result row.

The binding values are numbered from left to right using the text of the SELECT statement. The indexes start from 0.

An invalid QVariant is returned if binding value index does not exist, if the query is inactive, or if the query is positioned on an invalid result row.

See also: binding() previous() next() first() last() setPos() isValid()

◆ waitForFinished()

void QSparqlResult::waitForFinished ( )

virtual

Suspends the execution of the calling thread until all the query results have arrived. After this function returns, isFinished() should return true, indicating the result's contents are ready to be processed.

Warning: Calling this function from the main thread (the thread that calls QApplication::exec()) may cause your user interface to freeze.; Calling this function may cause the events in your event queue to be processed.

See also: isFinished()

The documentation for this class was generated from the following files:

/home/abuild/rpmbuild/BUILD/libqt5sparql-0.2.22.1/src/sparql/kernel/qsparqlresult.h
/home/abuild/rpmbuild/BUILD/libqt5sparql-0.2.22.1/src/sparql/kernel/qsparqlresult.cpp

Public Types

Signals

Public Member Functions

Protected Member Functions

Friends

Detailed Description

Member Enumeration Documentation

◆ Feature

Constructor & Destructor Documentation

◆ ~QSparqlResult()

◆ QSparqlResult()

Member Function Documentation

◆ binding()

◆ boolValue()

◆ current()

◆ dataReady

◆ finished

◆ first()

◆ hasError()

◆ hasFeature()

◆ isBool()

◆ isFinished()

◆ isGraph()

◆ isTable()

◆ isValid()

◆ last()

◆ lastError()

◆ next()

◆ pos()

◆ previous()

◆ query()

◆ setBoolValue()

◆ setLastError()

◆ setPos()

◆ setQuery()

◆ size()

◆ stringValue()

◆ updatePos()

◆ value()

◆ waitForFinished()