A feature iterator which iterates over features from a QgsVectorLayer. More...

#include <qgsvectorlayerfeatureiterator.h>

Inheritance diagram for QgsVectorLayerFeatureIterator:

[legend]

Classes
struct	FetchJoinInfo
	Join information prepared for fast attribute id mapping in QgsVectorLayerJoinBuffer::updateFeatureAttributes(). More...

Public Member Functions
	QgsVectorLayerFeatureIterator (QgsVectorLayerFeatureSource *source, bool ownSource, const QgsFeatureRequest &request)

	~QgsVectorLayerFeatureIterator () override

bool	close () override
	end of iterating: free the resources / lock

bool	isValid () const override
	Returns if this iterator is valid.

bool	rewind () override
	reset the iterator to the starting position

void	setInterruptionChecker (QgsFeedback *interruptionChecker) override
	Attach an object that can be queried regularly by the iterator to check if it must stopped.

Public Member Functions inherited from QgsAbstractFeatureIteratorFromSource< QgsVectorLayerFeatureSource >
	QgsAbstractFeatureIteratorFromSource (QgsVectorLayerFeatureSource *source, bool ownSource, const QgsFeatureRequest &request)

	~QgsAbstractFeatureIteratorFromSource () override

Public Member Functions inherited from QgsAbstractFeatureIterator
	QgsAbstractFeatureIterator (const QgsFeatureRequest &request)
	base class constructor - stores the iteration parameters

virtual	~QgsAbstractFeatureIterator ()=default
	destructor makes sure that the iterator is closed properly

bool	compileFailed () const
	Indicator if there was an error when sending the compiled query to the server.

CompileStatus	compileStatus () const
	Returns the status of expression compilation for filter expression requests.

virtual bool	nextFeature (QgsFeature &f)
	Fetch next feature and stores in f, returns `true` on success.

Protected Member Functions
void	addExpressionAttribute (QgsFeature &f, int attrIndex)
	Adds an expression based attribute to a feature.

void	addJoinedAttributes (QgsFeature &f)

void	addVirtualAttributes (QgsFeature &f)
	Adds attributes that don't source from the provider but are added inside QGIS Includes.

bool	fetchFeature (QgsFeature &feature) override
	fetch next feature, return `true` on success

bool	fetchNextAddedFeature (QgsFeature &f)

bool	fetchNextChangedAttributeFeature (QgsFeature &f)

bool	fetchNextChangedGeomFeature (QgsFeature &f)

bool	nextFeatureFid (QgsFeature &f)

bool	nextFeatureFilterExpression (QgsFeature &f) override
	Overrides default method as we only need to filter features in the edit buffer while for others filtering is left to the provider implementation.

void	prepareExpression (int fieldIdx)

void	prepareField (int fieldIdx)

void	prepareFields ()

void	prepareJoin (int fieldIdx)

bool	prepareSimplification (const QgsSimplifyMethod &simplifyMethod) override
	Setup the simplification of geometries to fetch using the specified simplify method.

void	rewindEditBuffer ()

void	updateChangedAttributes (QgsFeature &f)
	Update feature with uncommitted attribute updates.

void	updateFeatureGeometry (QgsFeature &f)
	Update feature with uncommitted geometry updates.

void	useAddedFeature (const QgsFeature &src, QgsFeature &f)

void	useChangedAttributeFeature (QgsFeatureId fid, const QgsGeometry &geom, QgsFeature &f)

Protected Member Functions inherited from QgsAbstractFeatureIteratorFromSource< QgsVectorLayerFeatureSource >
void	iteratorClosed ()
	to be called by from subclass in close()

Protected Member Functions inherited from QgsAbstractFeatureIterator
void	deref ()
	Remove reference, delete if refs == 0.

QgsRectangle	filterRectToSourceCrs (const QgsCoordinateTransform &transform) const
	Returns a rectangle representing the original request's QgsFeatureRequest::filterRect().

void	geometryToDestinationCrs (QgsFeature &feature, const QgsCoordinateTransform &transform) const
	Transforms feature's geometry according to the specified coordinate transform.

virtual bool	nextFeatureFilterFids (QgsFeature &f)
	By default, the iterator will fetch all features and check if the id is in the request.

void	ref ()
	Add reference.

RequestToSourceCrsResult	updateRequestToSourceCrs (QgsFeatureRequest &request, const QgsCoordinateTransform &transform) const
	Update a QgsFeatureRequest so that spatial filters are transformed to the source's coordinate reference system.

Protected Attributes
QgsFeatureIterator	mChangedFeaturesIterator

QgsFeatureRequest	mChangedFeaturesRequest

double	mDistanceWithin = 0

std::shared_ptr< QgsGeometryEngine >	mDistanceWithinEngine

QgsGeometry	mDistanceWithinGeom

QMap< int, QgsExpression * >	mExpressionFieldInfo

QgsFeatureMap::ConstIterator	mFetchAddedFeaturesIt

QgsGeometryMap::ConstIterator	mFetchChangedGeomIt

QSet< QgsFeatureId >	mFetchConsidered

bool	mFetchedFid

QMap< const QgsVectorLayerJoinInfo *, QgsVectorLayerFeatureIterator::FetchJoinInfo >	mFetchJoinInfo
	Information about joins used in the current select() statement.

QgsRectangle	mFilterRect

bool	mHasValidTransform = false

bool	mHasVirtualAttributes

QgsFeatureIterator	mProviderIterator

QgsFeatureRequest	mProviderRequest

QgsCoordinateTransform	mTransform

Protected Attributes inherited from QgsAbstractFeatureIteratorFromSource< QgsVectorLayerFeatureSource >
bool	mOwnSource

QgsVectorLayerFeatureSource *	mSource

Protected Attributes inherited from QgsAbstractFeatureIterator
bool	mClosed = false
	Sets to `true`, as soon as the iterator is closed.

bool	mCompileFailed = false

CompileStatus	mCompileStatus = NoCompilation
	Status of compilation of filter expression.

long long	mFetchedCount = 0
	Number of features already fetched by iterator.

QgsFeatureRequest	mRequest
	A copy of the feature request.

bool	mValid = true
	An invalid state of a feature iterator indicates that there was a problem with even getting it up and running.

bool	mZombie = false
	A feature iterator may be closed already but still be serving features from the cache.

int	refs = 0
	reference counting (to allow seamless copying of QgsFeatureIterator instances)

Additional Inherited Members
Public Types inherited from QgsAbstractFeatureIterator
enum	CompileStatus { NoCompilation , PartiallyCompiled , Compiled }
	Status of expression compilation for filter expression requests. More...

enum class	RequestToSourceCrsResult : int { Success , DistanceWithinMustBeCheckedManually }
	Possible results from the updateRequestToSourceCrs() method. More...

Detailed Description

A feature iterator which iterates over features from a QgsVectorLayer.

Definition at line 154 of file qgsvectorlayerfeatureiterator.h.

Constructor & Destructor Documentation

◆ QgsVectorLayerFeatureIterator()

QgsVectorLayerFeatureIterator::QgsVectorLayerFeatureIterator	(	QgsVectorLayerFeatureSource *	source,
		bool	ownSource,
		const QgsFeatureRequest &	request
	)

Definition at line 137 of file qgsvectorlayerfeatureiterator.cpp.

◆ ~QgsVectorLayerFeatureIterator()

QgsVectorLayerFeatureIterator::~QgsVectorLayerFeatureIterator ( )

override

Definition at line 368 of file qgsvectorlayerfeatureiterator.cpp.

Member Function Documentation

◆ addExpressionAttribute()

void QgsVectorLayerFeatureIterator::addExpressionAttribute	(	QgsFeature &	f,
		int	attrIndex
	)

protected

Adds an expression based attribute to a feature.

Parameters

f	feature
attrIndex	attribute index

Note: not available in Python bindings

Definition at line 1120 of file qgsvectorlayerfeatureiterator.cpp.

◆ addJoinedAttributes()

void QgsVectorLayerFeatureIterator::addJoinedAttributes ( QgsFeature & f )

protected

Note: not available in Python bindings

Definition at line 1063 of file qgsvectorlayerfeatureiterator.cpp.

◆ addVirtualAttributes()

void QgsVectorLayerFeatureIterator::addVirtualAttributes ( QgsFeature & f )

protected

Adds attributes that don't source from the provider but are added inside QGIS Includes.

Joined fields
Expression fields

Parameters

f	The feature will be modified

Note: not available in Python bindings

Definition at line 1080 of file qgsvectorlayerfeatureiterator.cpp.

◆ close()

bool QgsVectorLayerFeatureIterator::close ( )

overridevirtual

end of iterating: free the resources / lock

Implements QgsAbstractFeatureIterator.

Definition at line 602 of file qgsvectorlayerfeatureiterator.cpp.

◆ fetchFeature()

bool QgsVectorLayerFeatureIterator::fetchFeature ( QgsFeature & feature )

overrideprotectedvirtual

fetch next feature, return true on success

Implements QgsAbstractFeatureIterator.

Definition at line 466 of file qgsvectorlayerfeatureiterator.cpp.

◆ fetchNextAddedFeature()

bool QgsVectorLayerFeatureIterator::fetchNextAddedFeature ( QgsFeature & f )

protected

Note: not available in Python bindings

Definition at line 626 of file qgsvectorlayerfeatureiterator.cpp.

◆ fetchNextChangedAttributeFeature()

bool QgsVectorLayerFeatureIterator::fetchNextChangedAttributeFeature ( QgsFeature & f )

protected

Note: not available in Python bindings

Definition at line 712 of file qgsvectorlayerfeatureiterator.cpp.

◆ fetchNextChangedGeomFeature()

bool QgsVectorLayerFeatureIterator::fetchNextChangedGeomFeature ( QgsFeature & f )

protected

Note: not available in Python bindings

Definition at line 673 of file qgsvectorlayerfeatureiterator.cpp.

◆ isValid()

bool QgsVectorLayerFeatureIterator::isValid ( ) const

overridevirtual

Returns if this iterator is valid.

An invalid feature iterator is not able to provide a reliable source for data. If an iterator is invalid, either give up or try to send the request again (preferably after a timeout to give the system some time to stay responsive).

If you want to check if the iterator successfully completed, better use QgsFeatureIterator::isClosed().

Reimplemented from QgsAbstractFeatureIterator.

Definition at line 621 of file qgsvectorlayerfeatureiterator.cpp.

◆ nextFeatureFid()

bool QgsVectorLayerFeatureIterator::nextFeatureFid ( QgsFeature & f )

protected

Note: not available in Python bindings

Definition at line 1262 of file qgsvectorlayerfeatureiterator.cpp.

◆ nextFeatureFilterExpression()

bool QgsVectorLayerFeatureIterator::nextFeatureFilterExpression ( QgsFeature & f )

inlineoverrideprotectedvirtual

Overrides default method as we only need to filter features in the edit buffer while for others filtering is left to the provider implementation.

Reimplemented from QgsAbstractFeatureIterator.

Definition at line 223 of file qgsvectorlayerfeatureiterator.h.

◆ prepareExpression()

void QgsVectorLayerFeatureIterator::prepareExpression ( int fieldIdx )

protected

Note: not available in Python bindings

Definition at line 836 of file qgsvectorlayerfeatureiterator.cpp.

◆ prepareField()

void QgsVectorLayerFeatureIterator::prepareField ( int fieldIdx )

protected

Note: not available in Python bindings

Definition at line 1041 of file qgsvectorlayerfeatureiterator.cpp.

◆ prepareFields()

void QgsVectorLayerFeatureIterator::prepareFields ( )

protected

Note: not available in Python bindings

Definition at line 895 of file qgsvectorlayerfeatureiterator.cpp.

◆ prepareJoin()

void QgsVectorLayerFeatureIterator::prepareJoin ( int fieldIdx )

protected

Note: not available in Python bindings

Definition at line 794 of file qgsvectorlayerfeatureiterator.cpp.

◆ prepareSimplification()

bool QgsVectorLayerFeatureIterator::prepareSimplification ( const QgsSimplifyMethod & simplifyMethod )

overrideprotectedvirtual

Setup the simplification of geometries to fetch using the specified simplify method.

Reimplemented from QgsAbstractFeatureIterator.

Definition at line 1139 of file qgsvectorlayerfeatureiterator.cpp.

◆ rewind()

bool QgsVectorLayerFeatureIterator::rewind ( )

overridevirtual

reset the iterator to the starting position

Implements QgsAbstractFeatureIterator.

Definition at line 584 of file qgsvectorlayerfeatureiterator.cpp.

◆ rewindEditBuffer()

void QgsVectorLayerFeatureIterator::rewindEditBuffer ( )

protected

Note: not available in Python bindings

Definition at line 786 of file qgsvectorlayerfeatureiterator.cpp.

◆ setInterruptionChecker()

void QgsVectorLayerFeatureIterator::setInterruptionChecker ( QgsFeedback * interruptionChecker )

overridevirtual

Attach an object that can be queried regularly by the iterator to check if it must stopped.

This is mostly useful for iterators where a single nextFeature()/fetchFeature() iteration might be very long. A typical use case is the WFS provider. When nextFeature()/fetchFeature() is reasonably fast, it is not necessary to implement this method. The default implementation does nothing.