The feature class encapsulates a single feature including its id, geometry and a list of field/values attributes. More...

#include <qgsfeature.h>

Collaboration diagram for QgsFeature:

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Public Member Functions
	QgsFeature (QgsFeatureId id=QgsFeatureId())
	Constructor.
	QgsFeature (const QgsFields &fields, QgsFeatureId id=QgsFeatureId())
	QgsFeature (const QgsFeature &rhs)
	copy ctor needed due to internal pointer
QgsFeature &	operator= (QgsFeature const &rhs)
	assignment operator needed due to internal pointer
	~QgsFeature ()
	Destructor.
QgsFeatureId	id () const
	Get the feature id for this feature.
void	setFeatureId (QgsFeatureId id)
	Set the feature id for this feature.
const QgsAttributes &	attributes () const
QgsAttributes &	attributes ()
void	setAttributes (const QgsAttributes &attrs)
bool	setAttribute (int field, const QVariant &attr)
	Set an attribute by id.
void	initAttributes (int fieldCount)
	Initialize this feature with the given number of fields.
void	deleteAttribute (int field)
	Deletes an attribute and its value.
bool	isValid () const
	Return the validity of this feature.
void	setValid (bool validity)
	Set the validity of the feature.
QgsGeometry *	geometry () const
	Get the geometry object associated with this feature.
QgsGeometry *	geometryAndOwnership ()
	Get the geometry object associated with this feature The caller assumes responsibility for the QgsGeometry*'s destruction.
void	setGeometry (const QgsGeometry &geom)
	Set this feature's geometry from another QgsGeometry object (deep copy)
void	setGeometry (QgsGeometry *geom)
	Set this feature's geometry (takes geometry ownership)
void	setGeometryAndOwnership (unsigned char *geom, size_t length)
	Set this feature's geometry from WKB.
void	setFields (const QgsFields *fields, bool initAttributes=false)
	Assign a field map with the feature to allow attribute access by attribute name.
const QgsFields *	fields () const
	Get associated field map.
bool	setAttribute (const QString &name, QVariant value)
	Insert a value into attribute.
bool	deleteAttribute (const QString &name)
	Remove an attribute value.
QVariant	attribute (const QString &name) const
	Lookup attribute value from attribute name.
QVariant	attribute (int fieldIdx) const
	Lookup attribute value from its index.
int	fieldNameIndex (const QString &fieldName) const
	Utility method to get attribute index from name.

Private Attributes
QgsFeatureId	mFid
	feature id
QgsAttributes	mAttributes
	attributes accessed by field index
QgsGeometry *	mGeometry
	pointer to geometry in binary WKB format
bool	mOwnsGeometry
	Indicator if the mGeometry is owned by this QgsFeature.
bool	mValid
	Flag to indicate if this feature is valid.
const QgsFields *	mFields
	Optional field map for name-based attribute lookups.

Detailed Description

The feature class encapsulates a single feature including its id, geometry and a list of field/values attributes.

Encapsulates a spatial feature with attributes.

Author: Gary E.Sherman

Definition at line 114 of file qgsfeature.h.

Constructor & Destructor Documentation

QgsFeature::QgsFeature ( QgsFeatureId id = QgsFeatureId() )

Constructor.

Definition at line 27 of file qgsfeature.cpp.

QgsFeature::QgsFeature	(	const QgsFields &	fields,
		QgsFeatureId	id = `QgsFeatureId()`
	)

Definition at line 37 of file qgsfeature.cpp.

References QgsFields::count(), and initAttributes().

QgsFeature::QgsFeature ( const QgsFeature & rhs )

copy ctor needed due to internal pointer

Definition at line 47 of file qgsfeature.cpp.

References mGeometry, and setGeometry().

QgsFeature::~QgsFeature ( )

Destructor.

Definition at line 90 of file qgsfeature.cpp.

References mGeometry, and mOwnsGeometry.

Member Function Documentation

QVariant QgsFeature::attribute ( const QString & name ) const

Lookup attribute value from attribute name.

Returns invalid variant if attribute name could not be converted to index (C++ only) Field map must be associated to make this work.

Parameters

name	The name of the attribute to get

Returns: The value of the attribute (C++: Invalid variant if no such name exists )

Note: For Python: raises a KeyError exception if field is not found; added in 2.0

Definition at line 231 of file qgsfeature.cpp.

References fieldNameIndex(), and mAttributes.

Referenced by QgsGeometryAnalyzer::addEventLayerFeature(), QgsVectorLayerFeatureIterator::addJoinedAttributes(), QgsDualView::attributeAdded(), QgsGeometryAnalyzer::bufferFeature(), QgsInterpolator::cacheBaseData(), QgsAttributeEditor::createAttributeEditor(), QgsVectorFileWriter::createFeature(), QgsGraduatedSymbolRendererV2::createRenderer(), QgsAttributeTableModel::data(), QgsPalLayerSettings::dataDefinedValue(), QgsAttributeAction::doAction(), QgsExpression::NodeColumnRef::eval(), QgsGeometryAnalyzer::eventLayer(), QgsMapTip::fetchFeature(), QgsLabel::fieldValue(), QgsSearchQueryBuilder::getFieldValues(), QgsTINInterpolator::insertData(), QgsAttributeTableModel::loadAttributes(), QgsVectorLayer::maximumValue(), QgsVectorLayer::minimumValue(), QgsAttributeTableModel::prefetchColumnData(), QgsVectorLayerUndoCommandDeleteAttribute::QgsVectorLayerUndoCommandDeleteAttribute(), QgsPalLabeling::registerDiagramFeature(), QgsPalLayerSettings::registerFeature(), QgsDualView::reloadAttribute(), QgsVectorFieldSymbolLayer::renderPoint(), QgsSingleSymbolRendererV2::symbolForFeature(), QgsVectorLayerUndoCommandChangeAttribute::undo(), QgsVectorDataProvider::uniqueValues(), and QgsVectorLayer::uniqueValues().

QVariant QgsFeature::attribute ( int fieldIdx ) const

Lookup attribute value from its index.

Returns invalid variant if the index does not exist.

Parameters

fieldIdx The index of the attribute to get

Returns: The value of the attribute (C++: Invalid variant if no such index exists )

Note: For Python: raises a KeyError exception if field is not found; added in 2.0

Definition at line 223 of file qgsfeature.cpp.

References mAttributes.

const QgsAttributes& QgsFeature::attributes ( ) const

inline

Definition at line 143 of file qgsfeature.h.

Referenced by QgsVectorLayerEditBuffer::addFeature(), QgsVectorLayerImport::addFeature(), QgsVectorLayerFeatureIterator::addJoinedAttributes(), QgsVectorLayerFeatureIterator::FetchJoinInfo::addJoinedAttributesDirect(), QgsOfflineEditing::applyFeaturesAdded(), QgsDualView::attributeAdded(), QgsAtlasComposition::beginRender(), QgsGeometryAnalyzer::bufferFeature(), QgsVectorLayerJoinBuffer::cacheJoinLayer(), QgsGeometryAnalyzer::centroidFeature(), QgsVectorLayerEditBuffer::commitChanges(), QgsOfflineEditing::copyVectorLayer(), QgsFormAnnotationItem::createDesignerWidget(), QgsVectorDataProvider::fillMinMaxCache(), QgsComposerAttributeTable::getFeatureAttributes(), QgsPointDisplacementRenderer::getLabel(), QgsOverlayAnalyzer::intersectFeature(), QgsAttributeDialog::QgsAttributeDialog(), QgsPalLabeling::registerDiagramFeature(), QgsDualView::saveEditChanges(), QgsGeometryAnalyzer::simplifyFeature(), QgsGraduatedSymbolRendererV2::symbolForFeature(), QgsCategorizedSymbolRendererV2::symbolForFeature(), QgsVectorLayerFeatureIterator::updateChangedAttributes(), QgsVectorLayerEditBuffer::updateChangedAttributes(), QgsVectorLayer::updateFeature(), QgsVectorLayerFeatureIterator::useAddedFeature(), and QgsVectorLayerFeatureIterator::useChangedAttributeFeature().

QgsAttributes& QgsFeature::attributes ( )

inline

Definition at line 144 of file qgsfeature.h.

void QgsFeature::deleteAttribute ( int field )

Deletes an attribute and its value.

Parameters

field The index of the field

Note: For Python: raises a KeyError exception if the field is not found

Definition at line 107 of file qgsfeature.cpp.

References mAttributes.

Referenced by QgsDualView::attributeDeleted().

bool QgsFeature::deleteAttribute ( const QString & name )

Remove an attribute value.

Returns false if attribute name could not be converted to index. Field map must be associated to make this work.

Parameters

name	The name of the field to delete

Returns: false if attribute name could not be converted to index (C++ only)

Note: For Python: raises a KeyError exception instead of returning false; added in 2.0

Definition at line 213 of file qgsfeature.cpp.

References fieldNameIndex(), and mAttributes.

int QgsFeature::fieldNameIndex ( const QString & fieldName ) const

Utility method to get attribute index from name.

Returns -1 if field does not exist or field map is not associated. Field map must be associated to make this work.

Note: added in 2.0

Definition at line 240 of file qgsfeature.cpp.

References QgsFields::at(), QgsFields::count(), mFields, and QgsField::name().

Referenced by attribute(), deleteAttribute(), and setAttribute().

const QgsFields* QgsFeature::fields ( ) const

inline

Get associated field map.

may be NULL

Note: added in 2.0

Definition at line 230 of file qgsfeature.h.

Referenced by setFields().

QgsGeometry * QgsFeature::geometry ( ) const

Get the geometry object associated with this feature.

Definition at line 113 of file qgsfeature.cpp.

References mGeometry.

Referenced by QgsVectorLayerImport::addFeature(), QgsVectorLayerEditUtils::addPart(), QgsVectorLayerEditUtils::addRing(), QgsVectorLayer::boundingBoxOfSelected(), QgsGeometryAnalyzer::bufferFeature(), QgsInterpolator::cacheBaseData(), QgsGml::calculateExtentFromFeatures(), QgsZonalStatistics::calculateStatistics(), QgsGeometryAnalyzer::centroidFeature(), QgsGeometryAnalyzer::convexFeature(), QgsPointDisplacementRenderer::createDisplacementGroups(), QgsVectorFileWriter::createFeature(), QgsGeometryAnalyzer::dissolveFeature(), QgsVectorLayer::drawRendererV2(), QgsVectorLayer::drawRendererV2Levels(), QgsGeometryAnalyzer::eventLayer(), QgsVectorFileWriter::exportFeaturesSymbolLevels(), QgsVectorLayer::extent(), fcnGeomArea(), fcnGeometry(), fcnGeomLength(), fcnGeomPerimeter(), QgsMapToolIdentify::featureDerivedAttributes(), QgsSpatialIndex::featureInfo(), QgsVectorLayerImport::importLayer(), QgsTINInterpolator::insertData(), QgsOverlayAnalyzer::intersectFeature(), QgsLabel::labelPoint(), QgsAtlasComposition::prepareForFeature(), QgsAttributeDialog::QgsAttributeDialog(), QgsVectorLayerUndoCommandAddFeature::redo(), QgsPalLabeling::registerDiagramFeature(), QgsPalLayerSettings::registerFeature(), QgsVectorLayer::removePolygonIntersections(), QgsPointDisplacementRenderer::renderFeature(), QgsFeatureRendererV2::renderFeatureWithSymbol(), QgsGeometryAnalyzer::simplifyFeature(), QgsVectorLayer::snapWithContext(), QgsVectorLayerEditUtils::translateFeature(), QgsVectorLayerUndoCommandAddFeature::undo(), QgsVectorLayerUndoCommandChangeGeometry::undo(), QgsVectorLayer::updateFeature(), QgsVectorLayerFeatureIterator::useAddedFeature(), and QgsVectorFileWriter::writeAsVectorFormat().

QgsGeometry * QgsFeature::geometryAndOwnership ( )

Get the geometry object associated with this feature The caller assumes responsibility for the QgsGeometry*'s destruction.

Definition at line 118 of file qgsfeature.cpp.

References mGeometry, and mOwnsGeometry.

QgsFeatureId QgsFeature::id ( ) const

Get the feature id for this feature.

Returns: Feature id

Definition at line 101 of file qgsfeature.cpp.

References mFid.

Referenced by QgsVectorLayerEditUtils::addRing(), QgsDualView::attributeAdded(), QgsAttributeTableModel::attributeValueChanged(), QgsAtlasComposition::beginRender(), QgsVectorLayer::boundingBoxOfSelected(), QgsVectorLayerCache::cacheFeature(), QgsZonalStatistics::calculateStatistics(), QgsVectorLayerEditBuffer::commitChanges(), QgsOfflineEditing::copyVectorLayer(), QgsPointDisplacementRenderer::createDisplacementGroups(), QgsVectorFileWriter::createFeature(), QgsFeatureListModel::data(), QgsAttributeTableModel::data(), QgsVectorLayer::drawRendererV2(), QgsVectorLayer::drawRendererV2Levels(), QgsGml::endElement(), QgsGeometryAnalyzer::eventLayer(), fcnFeatureId(), QgsDualView::featureDeleted(), QgsSpatialIndex::featureInfo(), QgsAttributeTableFilterModel::generateListOfVisibleFeatures(), QgsVectorLayerImport::importLayer(), QgsVectorLayer::invertSelection(), QgsVectorLayer::invertSelectionInRectangle(), QgsAttributeTableModel::loadLayer(), QgsVectorLayerFeatureIterator::nextFeature(), QgsCachedFeatureWriterIterator::nextFeature(), QgsExpressionSelectionDialog::on_mActionAddToSelection_triggered(), QgsExpressionSelectionDialog::on_mActionRemoveFromSelection_triggered(), QgsExpressionSelectionDialog::on_mActionSelect_triggered(), QgsExpressionSelectionDialog::on_mActionSelectInstersect_triggered(), QgsAttributeTableModel::prefetchColumnData(), QgsAttributeDialog::QgsAttributeDialog(), QgsVectorLayerUndoCommandDeleteAttribute::QgsVectorLayerUndoCommandDeleteAttribute(), QgsVectorLayerUndoCommandAddFeature::redo(), QgsPalLabeling::registerDiagramFeature(), QgsPalLayerSettings::registerFeature(), QgsDualView::reloadAttribute(), QgsVectorLayer::removePolygonIntersections(), QgsPointDisplacementRenderer::renderFeature(), QgsFeatureRendererV2::renderFeatureWithSymbol(), QgsDualView::saveEditChanges(), QgsVectorLayer::select(), QgsVectorLayer::selectAll(), QgsFormAnnotationItem::setFeatureForMapPosition(), QgsHtmlAnnotationItem::setFeatureForMapPosition(), setFeatureId(), QgsVectorLayer::snapWithContext(), QgsVectorLayerUndoCommandAddFeature::undo(), QgsVectorLayerUndoCommandDeleteFeature::undo(), QgsVectorLayerUndoCommandDeleteAttribute::undo(), QgsVectorLayerFeatureIterator::updateChangedAttributes(), QgsVectorLayerEditBuffer::updateChangedAttributes(), QgsVectorLayer::updateFeature(), QgsVectorLayerFeatureIterator::updateFeatureGeometry(), QgsVectorLayerEditBuffer::updateFeatureGeometry(), QgsOfflineEditing::updateFidLookup(), QgsVectorLayerFeatureIterator::useAddedFeature(), and QgsVectorFileWriter::writeAsVectorFormat().

void QgsFeature::initAttributes ( int fieldCount )

Initialize this feature with the given number of fields.

Discard any previously set attribute data.

Parameters

fieldCount Number of fields to initialize

Definition at line 182 of file qgsfeature.cpp.

References mAttributes.

Referenced by QgsVectorLayerImport::addFeature(), QgsAttributeTableModel::feature(), QgsVectorLayerImport::importLayer(), QgsFeature(), setFields(), and QgsVectorFileWriter::writeAsVectorFormat().

bool QgsFeature::isValid ( ) const

Return the validity of this feature.

This is normally set by the provider to indicate some problem that makes the feature invalid or to indicate a null feature.

Definition at line 172 of file qgsfeature.cpp.

References mValid.

Referenced by QgsAttributeTableModel::data(), QgsDualView::on_mFeatureList_currentEditSelectionChanged(), and QgsExpressionBuilderWidget::on_txtExpressionString_textChanged().

QgsFeature & QgsFeature::operator= ( QgsFeature const & rhs )

assignment operator needed due to internal pointer

Definition at line 64 of file qgsfeature.cpp.

References mAttributes, mFid, mFields, mGeometry, mOwnsGeometry, mValid, and setGeometry().

bool QgsFeature::setAttribute	(	int	field,
		const QVariant &	attr
	)

Set an attribute by id.

Parameters

field	The index of the field to set
attr	The value of the attribute

Returns: false, if the field id does not exist

Note: For Python: raises a KeyError exception instead of returning false

Definition at line 191 of file qgsfeature.cpp.

References QgsMessageLog::logMessage(), mAttributes, tr, and QgsMessageLog::WARNING.

Referenced by QgsAttributeDialog::accept(), QgsVectorLayerImport::addFeature(), QgsVectorLayerFeatureIterator::FetchJoinInfo::addJoinedAttributesCached(), QgsVectorLayerFeatureIterator::FetchJoinInfo::addJoinedAttributesDirect(), QgsDualView::attributeAdded(), QgsGml::endElement(), QgsAttributeTableModel::feature(), QgsVectorLayerCache::onAttributeValueChanged(), QgsDualView::reloadAttribute(), and QgsVectorLayerUndoCommandDeleteAttribute::undo().

bool QgsFeature::setAttribute	(	const QString &	name,
		QVariant	value
	)

Insert a value into attribute.

Returns false if attribute name could not be converted to index. Field map must be associated to make this work.

Parameters

name	The name of the field to set
value	The value to set

Returns: false if attribute name could not be converted to index (C++ only)

Note: For Python: raises a KeyError exception instead of returning false; added in 2.0

Definition at line 203 of file qgsfeature.cpp.

References fieldNameIndex(), and mAttributes.

void QgsFeature::setAttributes ( const QgsAttributes & attrs )

inline

Definition at line 145 of file qgsfeature.h.

Referenced by QgsOfflineEditing::applyFeaturesAdded(), QgsGeometryAnalyzer::bufferFeature(), QgsGeometryAnalyzer::centroidFeature(), QgsGeometryAnalyzer::convexHull(), QgsOfflineEditing::copyVectorLayer(), QgsGeometryAnalyzer::dissolve(), QgsGeometryAnalyzer::extent(), QgsOverlayAnalyzer::intersectFeature(), QgsGeometryAnalyzer::simplifyFeature(), QgsVectorLayerEditUtils::splitFeatures(), QgsGml::startElement(), QgsVectorLayerFeatureIterator::useAddedFeature(), and QgsVectorLayerFeatureIterator::useChangedAttributeFeature().

void QgsFeature::setFeatureId ( QgsFeatureId id )

Set the feature id for this feature.

Set the feature id.

Parameters

id	Feature id

Definition at line 129 of file qgsfeature.cpp.

References id(), and mFid.

Referenced by QgsAttributeTableModel::feature(), QgsAttributeTableModel::QgsAttributeTableModel(), QgsVectorLayerUndoCommandAddFeature::QgsVectorLayerUndoCommandAddFeature(), QgsAttributeTableModel::reload(), QgsVectorLayerFeatureIterator::useAddedFeature(), and QgsVectorLayerFeatureIterator::useChangedAttributeFeature().

void QgsFeature::setFields	(	const QgsFields *	fields,
		bool	initAttributes = `false`
	)

Assign a field map with the feature to allow attribute access by attribute name.

Parameters

fields	The attribute fields which this feature holds. When used from python, make sure a copy of the fields is held by python, as ownership stays there. I.e. Do not call feature.setFields( myDataProvider.fields() ) but instead call myFields = myDataProvider.fields() feature.setFields( myFields )
initAttributes	If true, attributes are initialized. Clears any data previously assigned. C++: Defaults to false Python: Defaults to true