Manages joined fields for a vector layer. More...

#include <qgsvectorlayerjoinbuffer.h>

Inheritance diagram for QgsVectorLayerJoinBuffer:

[legend]

Signals
void	joinedFieldsChanged ()
	Emitted whenever the list of joined fields changes (e.g.

Public Member Functions
	QgsVectorLayerJoinBuffer (QgsVectorLayer *layer=nullptr)
bool	addFeatures (QgsFeatureList &features, QgsFeatureSink::Flags flags=QgsFeatureSink::Flags()) override
	Adds a list of features in joined layers.
bool	addJoin (const QgsVectorLayerJoinInfo &joinInfo)
	Joins another vector layer to this layer.
bool	changeAttributeValue (QgsFeatureId fid, int field, const QVariant &newValue, const QVariant &oldValue=QVariant())
	Changes attribute value in joined layers.
bool	changeAttributeValues (QgsFeatureId fid, const QgsAttributeMap &newValues, const QgsAttributeMap &oldValues=QgsAttributeMap())
	Changes attributes' values in joined layers.
QgsVectorLayerJoinBuffer *	clone () const
	Create a copy of the join buffer.
bool	containsJoins () const
	Quick way to test if there is any join at all.
void	createJoinCaches ()
	Calls cacheJoinLayer() for all vector joins.
bool	deleteFeature (QgsFeatureId fid, QgsVectorLayer::DeleteContext *context=nullptr) const
	Deletes a feature from joined layers.
bool	deleteFeatures (const QgsFeatureIds &fids, QgsVectorLayer::DeleteContext *context=nullptr) const
	Deletes a list of features from joined layers.
bool	isAuxiliaryJoin (const QgsVectorLayerJoinInfo &info) const
	Returns `true` if the join information is about auxiliary layer, `false` otherwise.
QgsFeature	joinedFeatureOf (const QgsVectorLayerJoinInfo *info, const QgsFeature &feature) const
	Returns the joined feature corresponding to the feature.
int	joinedFieldsOffset (const QgsVectorLayerJoinInfo *info, const QgsFields &fields)
	Find out what is the first index of the join within fields.
const QgsVectorLayerJoinInfo *	joinForFieldIndex (int index, const QgsFields &fields, int &sourceFieldIndex) const
	Finds the vector join for a layer field index.
QList< const QgsVectorLayerJoinInfo * >	joinsWhereFieldIsId (const QgsField &field) const
	Returns joins where the field of a target layer is considered as an id.
void	readXml (const QDomNode &layer_node)
	Reads joins from project file.
bool	removeJoin (const QString &joinLayerId)
	Removes a vector layer join.
void	resolveReferences (QgsProject *project)
	Resolves layer IDs of joined layers using given project's available layers.
QgsFeature	targetedFeatureOf (const QgsVectorLayerJoinInfo *info, const QgsFeature &feature) const
	Returns the targeted feature corresponding to the joined feature.
void	updateFields (QgsFields &fields)
	Updates field map with joined attributes.
const QgsVectorJoinList &	vectorJoins () const
void	writeXml (QDomNode &layer_node, QDomDocument &document) const
	Saves mVectorJoins to xml under the layer node.
Public Member Functions inherited from QgsFeatureSink
virtual	~QgsFeatureSink ()=default
virtual bool	addFeature (QgsFeature &feature, QgsFeatureSink::Flags flags=QgsFeatureSink::Flags())
	Adds a single feature to the sink.
virtual bool	addFeatures (QgsFeatureIterator &iterator, QgsFeatureSink::Flags flags=QgsFeatureSink::Flags())
	Adds all features from the specified iterator to the sink.
virtual void	finalize ()
	Finalizes the sink, flushing any buffered features to the destination.
virtual bool	flushBuffer ()
	Flushes any internal buffer which may exist in the sink, causing any buffered features to be added to the sink's destination.
virtual QString	lastError () const
	Returns the most recent error encountered by the sink, e.g.

Static Public Member Functions
static QVector< int >	joinSubsetIndices (const QgsFields &joinLayerFields, const QStringList &joinFieldsSubset)
	Returns a vector of indices for use in join based on field names from the join layer's fields.
static QVector< int >	joinSubsetIndices (QgsVectorLayer *joinLayer, const QStringList &joinFieldsSubset)
	Returns a vector of indices for use in join based on field names from the layer.

Additional Inherited Members
Public Types inherited from QgsFeatureSink
enum	Flag { FastInsert = 1 << 1 , RollBackOnErrors = 1 << 2 }
	Flags controlling how features are added to a sink. More...
typedef QFlags< Flag >	Flags
enum	SinkFlag { RegeneratePrimaryKey = 1 << 1 }
	Flags that can be set on a QgsFeatureSink. More...
typedef QFlags< SinkFlag >	SinkFlags

Detailed Description

Manages joined fields for a vector layer.

Definition at line 36 of file qgsvectorlayerjoinbuffer.h.

Constructor & Destructor Documentation

◆ QgsVectorLayerJoinBuffer()

QgsVectorLayerJoinBuffer::QgsVectorLayerJoinBuffer ( QgsVectorLayer * layer = nullptr )

Definition at line 30 of file qgsvectorlayerjoinbuffer.cpp.

Member Function Documentation

◆ addFeatures()

bool QgsVectorLayerJoinBuffer::addFeatures	(	QgsFeatureList &	features,
		QgsFeatureSink::Flags	flags = QgsFeatureSink::Flags() )

overridevirtual

Adds a list of features in joined layers.

Features given in parameter are those added in target layer. If a corresponding joined feature yet exists in a joined layer, then this feature is just updated. Note that if a corresponding joined feature has only empty fields, then it's not created nor added.

Parameters

features	The list of features added in the target layer
flags	Unused parameter

Returns: false if an error happened, true otherwise

Implements QgsFeatureSink.

Definition at line 564 of file qgsvectorlayerjoinbuffer.cpp.

◆ addJoin()

bool QgsVectorLayerJoinBuffer::addJoin ( const QgsVectorLayerJoinInfo & joinInfo )

Joins another vector layer to this layer.

Parameters

joinInfo join object containing join layer id, target and source field

Returns: (since 2.6) whether the join was successfully added

Definition at line 66 of file qgsvectorlayerjoinbuffer.cpp.

◆ changeAttributeValue()

bool QgsVectorLayerJoinBuffer::changeAttributeValue	(	QgsFeatureId	fid,
		int	field,
		const QVariant &	newValue,
		const QVariant &	oldValue = QVariant() )

Changes attribute value in joined layers.

The feature id given in parameter is the one added in target layer. If the corresponding joined feature does not exist in a joined layer, then it's automatically created if its fields are not empty.

Parameters

fid	The feature id
field	The field to update
newValue	The new value of the attribute
oldValue	The old value of the attribute

Returns: false if an error happened, true otherwise

Definition at line 651 of file qgsvectorlayerjoinbuffer.cpp.

◆ changeAttributeValues()

bool QgsVectorLayerJoinBuffer::changeAttributeValues	(	QgsFeatureId	fid,
		const QgsAttributeMap &	newValues,
		const QgsAttributeMap &	oldValues = QgsAttributeMap() )

Changes attributes' values in joined layers.

The feature id given in parameter is the one added in target layer. If the corresponding joined feature does not exist in a joined layer, then it's automatically created if its fields are not empty.

Parameters

fid	The feature id
newValues	The new values for attributes
oldValues	The old values for attributes

Returns: false if an error happened, true otherwise

Definition at line 679 of file qgsvectorlayerjoinbuffer.cpp.

◆ clone()

QgsVectorLayerJoinBuffer * QgsVectorLayerJoinBuffer::clone ( ) const

Create a copy of the join buffer.

Definition at line 506 of file qgsvectorlayerjoinbuffer.cpp.

◆ containsJoins()

bool QgsVectorLayerJoinBuffer::containsJoins ( ) const

inline

Quick way to test if there is any join at all.

Definition at line 79 of file qgsvectorlayerjoinbuffer.h.

◆ createJoinCaches()

void QgsVectorLayerJoinBuffer::createJoinCaches ( )

Calls cacheJoinLayer() for all vector joins.

Definition at line 287 of file qgsvectorlayerjoinbuffer.cpp.

◆ deleteFeature()

bool QgsVectorLayerJoinBuffer::deleteFeature	(	QgsFeatureId	fid,
		QgsVectorLayer::DeleteContext *	context = nullptr ) const

Deletes a feature from joined layers.

The feature id given in parameter is the one coming from the target layer.

Parameters

fid	The feature id from the target layer to delete
context	The chain of features which will be deleted for feedback and to avoid infinite recursions. Can be `nullptr`.

Returns: false if an error happened, true otherwise

Definition at line 698 of file qgsvectorlayerjoinbuffer.cpp.

◆ deleteFeatures()

bool QgsVectorLayerJoinBuffer::deleteFeatures	(	const QgsFeatureIds &	fids,
		QgsVectorLayer::DeleteContext *	context = nullptr ) const

Deletes a list of features from joined layers.

Feature ids given in a parameter are those coming from the target layer.

Parameters

fids	Feature ids from the target layer to delete
context	The chain of features who will be deleted for feedback and to avoid infinite recursions. Can be `nullptr`.

Returns: false if an error happened, true otherwise

Definition at line 703 of file qgsvectorlayerjoinbuffer.cpp.

◆ isAuxiliaryJoin()

bool QgsVectorLayerJoinBuffer::isAuxiliaryJoin ( const QgsVectorLayerJoinInfo & info ) const

Returns true if the join information is about auxiliary layer, false otherwise.

Parameters

info	The join information

Returns: true if the join information is about auxiliary layer, false otherwise

Definition at line 726 of file qgsvectorlayerjoinbuffer.cpp.

◆ joinedFeatureOf()

QgsFeature QgsVectorLayerJoinBuffer::joinedFeatureOf	(	const QgsVectorLayerJoinInfo *	info,
		const QgsFeature &	feature ) const

Returns the joined feature corresponding to the feature.

Parameters

info	the vector join information
feature	the feature of the target layer

Definition at line 462 of file qgsvectorlayerjoinbuffer.cpp.

◆ joinedFieldsChanged

void QgsVectorLayerJoinBuffer::joinedFieldsChanged ( )

signal

Emitted whenever the list of joined fields changes (e.g.

added join or joined layer's fields change)

◆ joinedFieldsOffset()

int QgsVectorLayerJoinBuffer::joinedFieldsOffset	(	const QgsVectorLayerJoinInfo *	info,
		const QgsFields &	fields )

Find out what is the first index of the join within fields.

Returns -1 if join is not present

Definition at line 410 of file qgsvectorlayerjoinbuffer.cpp.

◆ joinForFieldIndex()

const QgsVectorLayerJoinInfo * QgsVectorLayerJoinBuffer::joinForFieldIndex	(	int	index,
		const QgsFields &	fields,
		int &	sourceFieldIndex ) const

Finds the vector join for a layer field index.

Parameters

index	this layers attribute index
fields	fields of the vector layer (including joined fields)
sourceFieldIndex	Output: field's index in source layer

Returns: the vector layer join info

Definition at line 430 of file qgsvectorlayerjoinbuffer.cpp.

◆ joinSubsetIndices() [1/2]

QVector< int > QgsVectorLayerJoinBuffer::joinSubsetIndices	(	const QgsFields &	joinLayerFields,
		const QStringList &	joinFieldsSubset )

static

Returns a vector of indices for use in join based on field names from the join layer's fields.

Since: QGIS 3.20

Definition at line 217 of file qgsvectorlayerjoinbuffer.cpp.

◆ joinSubsetIndices() [2/2]

QVector< int > QgsVectorLayerJoinBuffer::joinSubsetIndices	(	QgsVectorLayer *	joinLayer,
		const QStringList &	joinFieldsSubset )

static

Returns a vector of indices for use in join based on field names from the layer.

Definition at line 212 of file qgsvectorlayerjoinbuffer.cpp.

◆ joinsWhereFieldIsId()

QList< const QgsVectorLayerJoinInfo * > QgsVectorLayerJoinBuffer::joinsWhereFieldIsId ( const QgsField & field ) const

Returns joins where the field of a target layer is considered as an id.

Parameters

field the field of a target layer

Returns: a list of vector joins

Definition at line 445 of file qgsvectorlayerjoinbuffer.cpp.

◆ readXml()

void QgsVectorLayerJoinBuffer::readXml ( const QDomNode & layer_node )

Reads joins from project file.

Does not resolve layer IDs to layers - call resolveReferences() afterwards

Definition at line 348 of file qgsvectorlayerjoinbuffer.cpp.

◆ removeJoin()

bool QgsVectorLayerJoinBuffer::removeJoin ( const QString & joinLayerId )

Removes a vector layer join.

Returns: true if join was found and successfully removed

Definition at line 109 of file qgsvectorlayerjoinbuffer.cpp.

◆ resolveReferences()

void QgsVectorLayerJoinBuffer::resolveReferences ( QgsProject * project )

Resolves layer IDs of joined layers using given project's available layers.

Definition at line 390 of file qgsvectorlayerjoinbuffer.cpp.

◆ targetedFeatureOf()

QgsFeature QgsVectorLayerJoinBuffer::targetedFeatureOf	(	const QgsVectorLayerJoinInfo *	info,
		const QgsFeature &	feature ) const

Returns the targeted feature corresponding to the joined feature.

Parameters

info	the vector join information
feature	the feature of the joined layer

Definition at line 486 of file qgsvectorlayerjoinbuffer.cpp.

◆ updateFields()

void QgsVectorLayerJoinBuffer::updateFields ( QgsFields & fields )

Updates field map with joined attributes.

Parameters

fields map to append joined attributes

Definition at line 237 of file qgsvectorlayerjoinbuffer.cpp.

◆ vectorJoins()

const QgsVectorJoinList & QgsVectorLayerJoinBuffer::vectorJoins ( ) const

inline

Definition at line 81 of file qgsvectorlayerjoinbuffer.h.

◆ writeXml()

void QgsVectorLayerJoinBuffer::writeXml	(	QDomNode &	layer_node,
		QDomDocument &	document ) const

Saves mVectorJoins to xml under the layer node.

Definition at line 299 of file qgsvectorlayerjoinbuffer.cpp.

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

/build/qgis-3.99.0+git20251205+26c88405ac0+99sid/src/core/vector/qgsvectorlayerjoinbuffer.h
/build/qgis-3.99.0+git20251205+26c88405ac0+99sid/src/core/vector/qgsvectorlayerjoinbuffer.cpp

Signals

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QgsVectorLayerJoinBuffer()

Member Function Documentation

◆ addFeatures()

◆ addJoin()

◆ changeAttributeValue()

◆ changeAttributeValues()

◆ clone()

◆ containsJoins()

◆ createJoinCaches()

◆ deleteFeature()

◆ deleteFeatures()

◆ isAuxiliaryJoin()

◆ joinedFeatureOf()

◆ joinedFieldsChanged

◆ joinedFieldsOffset()

◆ joinForFieldIndex()

◆ joinSubsetIndices() [1/2]

◆ joinSubsetIndices() [2/2]

◆ joinsWhereFieldIsId()

◆ readXml()

◆ removeJoin()

◆ resolveReferences()

◆ targetedFeatureOf()

◆ updateFields()

◆ vectorJoins()

◆ writeXml()