QgsCachedFeatureWriterIterator Class Reference

Uses another iterator as backend and writes features to the cache. More...

#include <qgscachedfeatureiterator.h>

Inheritance diagram for QgsCachedFeatureWriterIterator:

Public Member Functions
	QgsCachedFeatureWriterIterator (QgsVectorLayerCache *vlCache, const QgsFeatureRequest &featureRequest)
	This constructor creates a feature iterator, which queries the backend and caches retrieved features.
bool	close () override
	Close this iterator.
bool	rewind () override
	Rewind to the beginning of the iterator.
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	isValid () const
	Returns if this iterator is valid.
virtual bool	nextFeature (QgsFeature &f)
	Fetch next feature and stores in f, returns true on success.
virtual void	setInterruptionChecker (QgsFeedback *interruptionChecker)
	Attach an object that can be queried regularly by the iterator to check if it must stopped.

Protected Member Functions
bool	fetchFeature (QgsFeature &f) override
	Implementation for fetching a feature.
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	nextFeatureFilterExpression (QgsFeature &f)
	By default, the iterator will fetch all features and check if the feature matches the expression.
virtual bool	nextFeatureFilterFids (QgsFeature &f)
	By default, the iterator will fetch all features and check if the id is in the request.
virtual bool	prepareSimplification (const QgsSimplifyMethod &simplifyMethod)
	Setup the simplification of geometries to fetch using the specified simplify method.
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.

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...
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)

Detailed Description

Uses another iterator as backend and writes features to the cache.

Definition at line 103 of file qgscachedfeatureiterator.h.

Constructor & Destructor Documentation

QgsCachedFeatureWriterIterator()

QgsCachedFeatureWriterIterator::QgsCachedFeatureWriterIterator	(	QgsVectorLayerCache *	vlCache,
		const QgsFeatureRequest &	featureRequest
	)

This constructor creates a feature iterator, which queries the backend and caches retrieved features.

Parameters

vlCache	The vector layer cache to use
featureRequest	The feature request to answer

Definition at line 139 of file qgscachedfeatureiterator.cpp.

Member Function Documentation

close()

bool QgsCachedFeatureWriterIterator::close ( )

overridevirtual

Close this iterator.

No further features will be available.

Returns

true if successful

Implements QgsAbstractFeatureIterator.

Definition at line 193 of file qgscachedfeatureiterator.cpp.

fetchFeature()

bool QgsCachedFeatureWriterIterator::fetchFeature ( QgsFeature &  f )

overrideprotectedvirtual

Implementation for fetching a feature.

Parameters

f	Will write to this feature

Returns

bool true if the operation was OK

Implements QgsAbstractFeatureIterator.

Definition at line 163 of file qgscachedfeatureiterator.cpp.

rewind()

bool QgsCachedFeatureWriterIterator::rewind ( )

overridevirtual

Rewind to the beginning of the iterator.

Returns

bool true if the operation was OK

Implements QgsAbstractFeatureIterator.

Definition at line 187 of file qgscachedfeatureiterator.cpp.

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

• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/qgscachedfeatureiterator.h
• /build/qgis-3.41.0+git20241122+3440c17df1d+99sid/src/core/qgscachedfeatureiterator.cpp