This class wraps a request for features to a vector layer (or directly its vector data provider). More...

#include <qgsfeaturerequest.h>

Collaboration diagram for QgsFeatureRequest:

Public Types
enum	Flag { NoFlags = 0, NoGeometry = 1, SubsetOfAttributes = 2, ExactIntersect = 4 }
enum	FilterType { FilterNone, FilterRect, FilterFid, FilterExpression, FilterFids }

Public Member Functions
	QgsFeatureRequest ()
	construct a default request: for all features get attributes and geometries
	QgsFeatureRequest (QgsFeatureId fid)
	construct a request with feature ID filter
	QgsFeatureRequest (const QgsRectangle &rect)
	construct a request with rectangle filter
	QgsFeatureRequest (const QgsExpression &expr)
	construct a request with a filter expression
	QgsFeatureRequest (const QgsFeatureRequest &rh)
	copy constructor
QgsFeatureRequest &	operator= (const QgsFeatureRequest &rh)
	~QgsFeatureRequest ()
FilterType	filterType () const
QgsFeatureRequest &	setFilterRect (const QgsRectangle &rect)
	Set rectangle from which features will be taken.
const QgsRectangle &	filterRect () const
QgsFeatureRequest &	setFilterFid (QgsFeatureId fid)
	Set feature ID that should be fetched.
const QgsFeatureId &	filterFid () const
QgsFeatureRequest &	setFilterFids (QgsFeatureIds fids)
	Set feature ID that should be fetched.
const QgsFeatureIds &	filterFids () const
QgsFeatureRequest &	setFilterExpression (const QString &expression)
	Set filter expression. {.
QgsExpression *	filterExpression () const
QgsFeatureRequest &	setFlags (Flags flags)
	Set flags that affect how features will be fetched.
const Flags &	flags () const
QgsFeatureRequest &	setSubsetOfAttributes (const QgsAttributeList &attrs)
	Set a subset of attributes that will be fetched.
const QgsAttributeList &	subsetOfAttributes () const
QgsFeatureRequest &	setSubsetOfAttributes (const QStringList &attrNames, const QgsFields &fields)
	Set a subset of attributes by names that will be fetched.
QgsFeatureRequest &	setSimplifyMethod (const QgsSimplifyMethod &simplifyMethod)
	Set a simplification method for geometries that will be fetched.
const QgsSimplifyMethod &	simplifyMethod () const
	Get simplification method for geometries that will be fetched.
bool	acceptFeature (const QgsFeature &feature)
	Check if a feature is accepted by this requests filter.

Protected Attributes
FilterType	mFilter
QgsRectangle	mFilterRect
QgsFeatureId	mFilterFid
QgsFeatureIds	mFilterFids
QgsExpression *	mFilterExpression
Flags	mFlags
QgsAttributeList	mAttrs
QgsSimplifyMethod	mSimplifyMethod

Detailed Description

This class wraps a request for features to a vector layer (or directly its vector data provider).

The request may apply a filter to fetch only a particular subset of features. Currently supported filters:

no filter - all features are returned
feature id - only feature that matches given feature id is returned
rectangle - only features that intersect given rectangle should be fetched. For the sake of speed, the intersection is often done only using feature's bounding box. There is a flag ExactIntersect that makes sure that only intersecting features will be returned.

For efficiency, it is also possible to tell provider that some data is not required:

NoGeometry flag
SubsetOfAttributes flag
SimplifyMethod for geometries to fetch

The options may be chained, e.g.: QgsFeatureRequest().setFilterRect(QgsRectangle(0,0,1,1)).setFlags(QgsFeatureRequest::ExactIntersect)

Examples:

fetch all features: QgsFeatureRequest()
fetch all features, only one attribute QgsFeatureRequest().setSubsetOfAttributes(QStringList("myfield"), provider->fieldMap())
fetch all features, without geometries QgsFeatureRequest().setFlags(QgsFeatureRequest::NoGeometry)
fetch only features from particular extent QgsFeatureRequest().setFilterRect(QgsRectangle(0,0,1,1))
fetch only one feature QgsFeatureRequest().setFilterFid(45)

Definition at line 58 of file qgsfeaturerequest.h.

Member Enumeration Documentation

enum QgsFeatureRequest::FilterType

Enumerator:

FilterNone	No filter is applied.
FilterRect	Filter using a rectangle, no need to set NoGeometry.
FilterFid	Filter using feature ID.
FilterExpression	Filter using expression.
FilterFids	Filter using feature IDs.

Definition at line 70 of file qgsfeaturerequest.h.

enum QgsFeatureRequest::Flag

Enumerator:

NoFlags
NoGeometry	Geometry is not required. It may still be returned if e.g. required for a filter condition.
SubsetOfAttributes	Fetch only a subset of attributes (setSubsetOfAttributes sets this flag)
ExactIntersect	Use exact geometry intersection (slower) instead of bounding boxes.

Definition at line 61 of file qgsfeaturerequest.h.

Constructor & Destructor Documentation

QgsFeatureRequest::QgsFeatureRequest ( )

construct a default request: for all features get attributes and geometries

Definition at line 22 of file qgsfeaturerequest.cpp.

QgsFeatureRequest::QgsFeatureRequest ( QgsFeatureId fid )

explicit

construct a request with feature ID filter

Definition at line 29 of file qgsfeaturerequest.cpp.

QgsFeatureRequest::QgsFeatureRequest ( const QgsRectangle & rect )

explicit

construct a request with rectangle filter

Definition at line 37 of file qgsfeaturerequest.cpp.

QgsFeatureRequest::QgsFeatureRequest ( const QgsExpression & expr )

explicit

construct a request with a filter expression

Definition at line 45 of file qgsfeaturerequest.cpp.

QgsFeatureRequest::QgsFeatureRequest ( const QgsFeatureRequest & rh )

copy constructor

Definition at line 52 of file qgsfeaturerequest.cpp.

References operator=().

QgsFeatureRequest::~QgsFeatureRequest ( )

Definition at line 77 of file qgsfeaturerequest.cpp.

References mFilterExpression.

Member Function Documentation

bool QgsFeatureRequest::acceptFeature ( const QgsFeature & feature )

Check if a feature is accepted by this requests filter.

Parameters

feature The feature which will be tested

Returns: true, if the filter accepts the feature

Note: added in 2.1

Definition at line 144 of file qgsfeaturerequest.cpp.

References QgsExpression::evaluate(), FilterExpression, FilterFid, FilterFids, FilterNone, FilterRect, QgsFeature::geometry(), QgsFeature::id(), QgsGeometry::intersects(), mFilter, mFilterExpression, mFilterFid, mFilterFids, and mFilterRect.

Referenced by QgsAttributeTableModel::attributeValueChanged(), QgsAttributeTableModel::featureAdded(), QgsCachedFeatureIterator::fetchFeature(), and QgsVectorLayerFeatureIterator::fetchNextAddedFeature().

QgsExpression* QgsFeatureRequest::filterExpression ( ) const

inline

Definition at line 111 of file qgsfeaturerequest.h.

Referenced by QgsVectorLayerFeatureIterator::fetchNextChangedAttributeFeature(), QgsAbstractFeatureIterator::nextFeatureFilterExpression(), and QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator().

const QgsFeatureId& QgsFeatureRequest::filterFid ( ) const

inline

Definition at line 103 of file qgsfeaturerequest.h.

Referenced by QgsCacheIndexFeatureId::getCacheIterator(), QgsVectorLayerFeatureIterator::nextFeatureFid(), QgsCachedFeatureIterator::QgsCachedFeatureIterator(), and QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator().

const QgsFeatureIds& QgsFeatureRequest::filterFids ( ) const

inline

Definition at line 107 of file qgsfeaturerequest.h.

Referenced by QgsAbstractFeatureIterator::nextFeatureFilterFids(), and QgsCachedFeatureIterator::QgsCachedFeatureIterator().

const QgsRectangle& QgsFeatureRequest::filterRect ( ) const

inline

Definition at line 99 of file qgsfeaturerequest.h.

Referenced by QgsVectorLayerFeatureIterator::fetchNextChangedGeomFeature().

FilterType QgsFeatureRequest::filterType ( ) const

inline

Definition at line 94 of file qgsfeaturerequest.h.

Referenced by QgsAttributeTableModel::attributeValueChanged(), QgsAttributeTableModel::featureAdded(), QgsAttributeTableModel::featureDeleted(), QgsVectorLayerFeatureIterator::fetchFeature(), QgsVectorLayerFeatureIterator::fetchNextChangedAttributeFeature(), QgsCacheIndexFeatureId::getCacheIterator(), QgsAbstractFeatureIterator::nextFeature(), QgsCachedFeatureIterator::QgsCachedFeatureIterator(), QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator(), and QgsVectorLayerFeatureIterator::rewind().

const Flags& QgsFeatureRequest::flags ( ) const

inline

Definition at line 115 of file qgsfeaturerequest.h.

Referenced by QgsVectorLayerCache::checkInformationCovered(), QgsVectorLayerFeatureIterator::fetchFeature(), QgsVectorLayerCache::getFeatures(), QgsVectorLayerFeatureIterator::nextFeatureFid(), QgsVectorLayerFeatureIterator::prepareJoins(), QgsVectorLayerFeatureIterator::prepareSimplification(), QgsAbstractFeatureIterator::prepareSimplification(), QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator(), setFlags(), QgsAttributeTableModel::setRequest(), QgsVectorLayerFeatureIterator::useAddedFeature(), and QgsVectorLayerFeatureIterator::useChangedAttributeFeature().

QgsFeatureRequest & QgsFeatureRequest::operator= ( const QgsFeatureRequest & rh )

Definition at line 57 of file qgsfeaturerequest.cpp.

References QgsExpression::expression(), mAttrs, mFilter, mFilterExpression, mFilterFid, mFilterFids, mFilterRect, mFlags, and mSimplifyMethod.

Referenced by QgsFeatureRequest().

QgsFeatureRequest & QgsFeatureRequest::setFilterExpression ( const QString & expression )

Set filter expression. {.

See Also: QgsExpression}

Definition at line 103 of file qgsfeaturerequest.cpp.

References FilterExpression, mFilter, and mFilterExpression.

Referenced by QgsRelation::getRelatedFeaturesRequest().

QgsFeatureRequest & QgsFeatureRequest::setFilterFid ( QgsFeatureId fid )

Set feature ID that should be fetched.

Definition at line 89 of file qgsfeaturerequest.cpp.

References FilterFid, mFilter, and mFilterFid.

Referenced by QgsVectorLayer::selectedFeatures(), QgsVectorLayerUndoCommandChangeAttribute::undo(), QgsVectorLayer::updateFeature(), and QgsVectorLayerFeatureIterator::useChangedAttributeFeature().

QgsFeatureRequest & QgsFeatureRequest::setFilterFids ( QgsFeatureIds fids )

Set feature ID that should be fetched.

Definition at line 96 of file qgsfeaturerequest.cpp.

References FilterFids, mFilter, and mFilterFids.

Referenced by QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator().

QgsFeatureRequest & QgsFeatureRequest::setFilterRect ( const QgsRectangle & rect )

Set rectangle from which features will be taken.

Empty rectangle removes the filter.

Definition at line 82 of file qgsfeaturerequest.cpp.

References FilterRect, mFilter, and mFilterRect.

Referenced by QgsVectorLayer::draw(), and QgsComposerAttributeTable::getFeatureAttributes().

QgsFeatureRequest & QgsFeatureRequest::setFlags ( Flags flags )

Set flags that affect how features will be fetched.

Definition at line 111 of file qgsfeaturerequest.cpp.

References flags(), and mFlags.

Referenced by QgsVectorLayerFeatureIterator::FetchJoinInfo::addJoinedAttributesDirect(), QgsComposerAttributeTable::getFeatureAttributes(), QgsVectorLayerCache::getFeatures(), QgsVectorLayerImport::importLayer(), QgsAttributeTableModel::QgsAttributeTableModel(), QgsVectorLayer::selectedFeatures(), QgsAttributeTableModel::setRequest(), QgsVectorLayerUndoCommandChangeAttribute::undo(), QgsVectorLayer::updateFeature(), QgsVectorLayerFeatureIterator::useChangedAttributeFeature(), and QgsVectorFileWriter::writeAsVectorFormat().

QgsFeatureRequest & QgsFeatureRequest::setSimplifyMethod ( const QgsSimplifyMethod & simplifyMethod )

Set a simplification method for geometries that will be fetched.

Note: added in 2.2

Definition at line 138 of file qgsfeaturerequest.cpp.

References mSimplifyMethod, and simplifyMethod().

Referenced by QgsVectorLayer::draw().

QgsFeatureRequest & QgsFeatureRequest::setSubsetOfAttributes ( const QgsAttributeList & attrs )

Set a subset of attributes that will be fetched.

Empty list means that all attributes are used. To disable fetching attributes, reset the FetchAttributes flag (which is set by default)

Definition at line 117 of file qgsfeaturerequest.cpp.

References mAttrs, mFlags, and SubsetOfAttributes.

Referenced by QgsVectorLayerFeatureIterator::FetchJoinInfo::addJoinedAttributesDirect(), QgsZonalStatistics::calculateStatistics(), QgsTransectSample::createSample(), QgsGeometryAnalyzer::eventLayer(), QgsComposerAttributeTable::getFeatureAttributes(), QgsVectorLayerCache::getFeatures(), QgsVectorLayerImport::importLayer(), QgsVectorLayerFeatureIterator::prepareJoins(), QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator(), QgsVectorLayerUndoCommandChangeAttribute::undo(), QgsVectorLayer::updateFeature(), QgsVectorLayerFeatureIterator::useChangedAttributeFeature(), and QgsVectorFileWriter::writeAsVectorFormat().

QgsFeatureRequest & QgsFeatureRequest::setSubsetOfAttributes	(	const QStringList &	attrNames,
		const QgsFields &	fields
	)

Set a subset of attributes by names that will be fetched.

Definition at line 124 of file qgsfeaturerequest.cpp.

References QgsFields::count(), mAttrs, mFlags, and SubsetOfAttributes.

const QgsSimplifyMethod& QgsFeatureRequest::simplifyMethod ( ) const

inline

Get simplification method for geometries that will be fetched.

Note: added in 2.2

Definition at line 130 of file qgsfeaturerequest.h.

Referenced by QgsAbstractFeatureIterator::ref(), and setSimplifyMethod().

const QgsAttributeList& QgsFeatureRequest::subsetOfAttributes ( ) const

inline

Definition at line 120 of file qgsfeaturerequest.h.

Referenced by QgsVectorLayerCache::checkInformationCovered(), QgsVectorLayerCache::getFeatures(), QgsVectorLayerFeatureIterator::prepareJoins(), QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator(), and QgsVectorLayerFeatureIterator::useChangedAttributeFeature().

Member Data Documentation

QgsAttributeList QgsFeatureRequest::mAttrs

protected

Definition at line 154 of file qgsfeaturerequest.h.

Referenced by operator=(), and setSubsetOfAttributes().

FilterType QgsFeatureRequest::mFilter

protected

Definition at line 148 of file qgsfeaturerequest.h.

Referenced by acceptFeature(), operator=(), setFilterExpression(), setFilterFid(), setFilterFids(), and setFilterRect().

QgsExpression* QgsFeatureRequest::mFilterExpression

protected

Definition at line 152 of file qgsfeaturerequest.h.

Referenced by acceptFeature(), operator=(), setFilterExpression(), and ~QgsFeatureRequest().

QgsFeatureId QgsFeatureRequest::mFilterFid

protected

Definition at line 150 of file qgsfeaturerequest.h.

Referenced by acceptFeature(), operator=(), and setFilterFid().

QgsFeatureIds QgsFeatureRequest::mFilterFids

protected

Definition at line 151 of file qgsfeaturerequest.h.

Referenced by acceptFeature(), operator=(), and setFilterFids().

QgsRectangle QgsFeatureRequest::mFilterRect

protected

Definition at line 149 of file qgsfeaturerequest.h.

Referenced by acceptFeature(), operator=(), and setFilterRect().

Flags QgsFeatureRequest::mFlags

protected

Definition at line 153 of file qgsfeaturerequest.h.

Referenced by operator=(), setFlags(), and setSubsetOfAttributes().

QgsSimplifyMethod QgsFeatureRequest::mSimplifyMethod

protected

Definition at line 155 of file qgsfeaturerequest.h.

Referenced by operator=(), and setSimplifyMethod().

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

/tmp/buildd/qgis-2.2.0+wheezy1/src/core/qgsfeaturerequest.h
/tmp/buildd/qgis-2.2.0+wheezy1/src/core/qgsfeaturerequest.cpp

Public Types

Public Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation