Contains utilities for working with QgsExpressionContext objects, including methods for creating scopes for specific uses (e.g., project scopes, layer scopes). More...

#include <qgsexpressioncontextutils.h>

Static Public Member Functions
static QgsExpressionContextScope *	atlasScope (const QgsLayoutAtlas *atlas)
	Creates a new scope which contains variables and functions relating to a QgsLayoutAtlas.
static QgsExpressionContext	createFeatureBasedContext (const QgsFeature &feature, const QgsFields &fields)
	Helper function for creating an expression context which contains just a feature and fields collection.
static QgsExpressionContextScope *	formScope (const QgsFeature &formFeature=QgsFeature(), const QString &formMode=QString())
	Creates a new scope which contains functions and variables from the current attribute form/table formFeature.
static QList< QgsExpressionContextScope * >	globalProjectLayerScopes (const QgsMapLayer *layer)
	Creates a list of three scopes: global, layer's project and layer.
static QgsExpressionContextScope *	globalScope ()
	Creates a new scope which contains variables and functions relating to the global QGIS context.
static QgsExpressionContextScope *	layerScope (const QgsMapLayer *layer)
	Creates a new scope which contains variables and functions relating to a QgsMapLayer.
static QgsExpressionContextScope *	layoutItemScope (const QgsLayoutItem *item)
	Creates a new scope which contains variables and functions relating to a QgsLayoutItem.
static QgsExpressionContextScope *	layoutScope (const QgsLayout *layout)
	Creates a new scope which contains variables and functions relating to a QgsLayout layout.
static QgsExpressionContextScope *	mapLayerPositionScope (const QgsPointXY &position)
	Sets the expression context variables which are available for expressions triggered by moving the mouse over a feature of the currently selected layer.
static QgsExpressionContextScope *	mapSettingsScope (const QgsMapSettings &mapSettings)
	Creates a new scope which contains variables and functions relating to a QgsMapSettings object.
static QgsExpressionContextScope *	mapToolCaptureScope (const QList< QgsPointLocator::Match > &matches)
	Sets the expression context variables which are available for expressions triggered by a map tool capture like add feature.
static QgsExpressionContextScope *	meshExpressionScope (QgsMesh::ElementType elementType)
	Creates a new scope which contains functions relating to mesh layer element elementType.
static QgsExpressionContextScope *	multiFrameScope (const QgsLayoutMultiFrame *frame)
	Creates a new scope which contains variables and functions relating to a QgsLayoutMultiFrame.
static QgsExpressionContextScope *	notificationScope (const QString &message=QString())
	Creates a new scope which contains variables and functions relating to provider notifications.
static QgsExpressionContextScope *	parentFormScope (const QgsFeature &formFeature=QgsFeature(), const QString &formMode=QString())
	Creates a new scope which contains functions and variables from the current parent attribute form/table formFeature.
static QgsExpressionContextScope *	processingAlgorithmScope (const QgsProcessingAlgorithm *algorithm, const QVariantMap &parameters, QgsProcessingContext &context)
	Creates a new scope which contains variables and functions relating to a processing algorithm, when used with the specified parameters and context.
static QgsExpressionContextScope *	processingModelAlgorithmScope (const QgsProcessingModelAlgorithm *model, const QVariantMap &parameters, QgsProcessingContext &context)
	Creates a new scope which contains variables and functions relating to a processing model algorithm, when used with the specified parameters and context.
static QgsExpressionContextScope *	projectScope (const QgsProject *project)
	Creates a new scope which contains variables and functions relating to a QGIS project.
static void	registerContextFunctions ()
	Registers all known core functions provided by QgsExpressionContextScope objects.
static void	removeGlobalVariable (const QString &name)
	Remove a global context variable.
static void	removeProjectVariable (QgsProject *project, const QString &name)
	Remove project context variable.
static void	setGlobalVariable (const QString &name, const QVariant &value)
	Sets a global context variable.
static void	setGlobalVariables (const QVariantMap &variables)
	Sets all global context variables.
static void	setLayerVariable (QgsMapLayer *layer, const QString &name, const QVariant &value)
	Sets a layer context variable.
static void	setLayerVariables (QgsMapLayer *layer, const QVariantMap &variables)
	Sets all layer context variables.
static void	setLayoutItemVariable (QgsLayoutItem *item, const QString &name, const QVariant &value)
	Sets a layout item context variable, with the given name and value.
static void	setLayoutItemVariables (QgsLayoutItem *item, const QVariantMap &variables)
	Sets all layout item context variables for an item.
static void	setLayoutMultiFrameVariable (QgsLayoutMultiFrame *frame, const QString &name, const QVariant &value)
	Sets a layout multi frame context variable, with the given name and value.
static void	setLayoutMultiFrameVariables (QgsLayoutMultiFrame *frame, const QVariantMap &variables)
	Sets all layout multiframe context variables for an frame.
static void	setLayoutVariable (QgsLayout *layout, const QString &name, const QVariant &value)
	Sets a layout context variable.
static void	setLayoutVariables (QgsLayout *layout, const QVariantMap &variables)
	Sets all layout context variables.
static void	setProjectVariable (QgsProject *project, const QString &name, const QVariant &value)
	Sets a project context variable.
static void	setProjectVariables (QgsProject *project, const QVariantMap &variables)
	Sets all project context variables.
static QgsExpressionContextScope *	updateSymbolScope (const QgsSymbol symbol, QgsExpressionContextScope symbolScope=nullptr)
	Updates a symbol scope related to a QgsSymbol to an expression context.

Friends
class	QgsLayoutItemMap

Detailed Description

Contains utilities for working with QgsExpressionContext objects, including methods for creating scopes for specific uses (e.g., project scopes, layer scopes).

Definition at line 47 of file qgsexpressioncontextutils.h.

Member Function Documentation

◆ atlasScope()

QgsExpressionContextScope * QgsExpressionContextUtils::atlasScope ( const QgsLayoutAtlas * atlas )

static

Creates a new scope which contains variables and functions relating to a QgsLayoutAtlas.

For instance, current page name and number.

Parameters

atlas source atlas. If nullptr, a set of default atlas variables will be added to the scope.

Definition at line 733 of file qgsexpressioncontextutils.cpp.

◆ createFeatureBasedContext()

QgsExpressionContext QgsExpressionContextUtils::createFeatureBasedContext	(	const QgsFeature &	feature,
		const QgsFields &	fields )

static

Helper function for creating an expression context which contains just a feature and fields collection.

Generally this method should not be used as the created context does not include standard scopes such as the global and project scopes.

Definition at line 938 of file qgsexpressioncontextutils.cpp.

◆ formScope()

QgsExpressionContextScope * QgsExpressionContextUtils::formScope	(	const QgsFeature &	formFeature = QgsFeature( ),
		const QString &	formMode = QString() )

static

Creates a new scope which contains functions and variables from the current attribute form/table formFeature.

The variables and values in this scope will reflect the current state of the form/row being edited. The formMode (SingleEditMode etc.) is passed as text

Since: QGIS 3.2

Definition at line 295 of file qgsexpressioncontextutils.cpp.

◆ globalProjectLayerScopes()

QList< QgsExpressionContextScope * > QgsExpressionContextUtils::globalProjectLayerScopes ( const QgsMapLayer * layer )

static

Creates a list of three scopes: global, layer's project and layer.

Definition at line 413 of file qgsexpressioncontextutils.cpp.

◆ globalScope()

QgsExpressionContextScope * QgsExpressionContextUtils::globalScope ( )

static

Creates a new scope which contains variables and functions relating to the global QGIS context.

For instance, QGIS version numbers and variables specified through QGIS options.

See also: setGlobalVariable()

Definition at line 46 of file qgsexpressioncontextutils.cpp.

◆ layerScope()

QgsExpressionContextScope * QgsExpressionContextUtils::layerScope ( const QgsMapLayer * layer )

static

Creates a new scope which contains variables and functions relating to a QgsMapLayer.

For instance, layer name, id and fields.

Definition at line 359 of file qgsexpressioncontextutils.cpp.

◆ layoutItemScope()

QgsExpressionContextScope * QgsExpressionContextUtils::layoutItemScope ( const QgsLayoutItem * item )

static

Creates a new scope which contains variables and functions relating to a QgsLayoutItem.

For instance, item size and position.

See also: setLayoutItemVariable(); setLayoutItemVariables()

Definition at line 772 of file qgsexpressioncontextutils.cpp.

◆ layoutScope()

QgsExpressionContextScope * QgsExpressionContextUtils::layoutScope ( const QgsLayout * layout )

static

Creates a new scope which contains variables and functions relating to a QgsLayout layout.

For instance, number of pages and page sizes.

Definition at line 616 of file qgsexpressioncontextutils.cpp.

◆ mapLayerPositionScope()

QgsExpressionContextScope * QgsExpressionContextUtils::mapLayerPositionScope ( const QgsPointXY & position )

static

Sets the expression context variables which are available for expressions triggered by moving the mouse over a feature of the currently selected layer.

Parameters

position map coordinates of the current pointer position in the CRS of the layer which triggered the action.

Since: QGIS 3.30

Definition at line 591 of file qgsexpressioncontextutils.cpp.

◆ mapSettingsScope()

QgsExpressionContextScope * QgsExpressionContextUtils::mapSettingsScope ( const QgsMapSettings & mapSettings )

static

Creates a new scope which contains variables and functions relating to a QgsMapSettings object.

For instance, map scale and rotation.

Definition at line 473 of file qgsexpressioncontextutils.cpp.

◆ mapToolCaptureScope()

QgsExpressionContextScope * QgsExpressionContextUtils::mapToolCaptureScope ( const QList< QgsPointLocator::Match > & matches )

static

Sets the expression context variables which are available for expressions triggered by a map tool capture like add feature.

Definition at line 567 of file qgsexpressioncontextutils.cpp.

◆ meshExpressionScope()

QgsExpressionContextScope * QgsExpressionContextUtils::meshExpressionScope ( QgsMesh::ElementType elementType )

static

Creates a new scope which contains functions relating to mesh layer element elementType.

Since: QGIS 3.22

◆ multiFrameScope()

QgsExpressionContextScope * QgsExpressionContextUtils::multiFrameScope ( const QgsLayoutMultiFrame * frame )

static

Creates a new scope which contains variables and functions relating to a QgsLayoutMultiFrame.

See also: setLayoutMultiFrameVariable(); setLayoutMultiFrameVariables()

Since: QGIS 3.10

Definition at line 877 of file qgsexpressioncontextutils.cpp.

◆ notificationScope()

QgsExpressionContextScope * QgsExpressionContextUtils::notificationScope ( const QString & message = QString() )

static

Creates a new scope which contains variables and functions relating to provider notifications.

Parameters

message the notification message

Definition at line 994 of file qgsexpressioncontextutils.cpp.

◆ parentFormScope()

QgsExpressionContextScope * QgsExpressionContextUtils::parentFormScope	(	const QgsFeature &	formFeature = QgsFeature( ),
		const QString &	formMode = QString() )

static

Creates a new scope which contains functions and variables from the current parent attribute form/table formFeature.

The variables and values in this scope will reflect the current state of the parent form/row being edited. The formMode (SingleEditMode etc.) is passed as text

Since: QGIS 3.14

Definition at line 306 of file qgsexpressioncontextutils.cpp.

◆ processingAlgorithmScope()

QgsExpressionContextScope * QgsExpressionContextUtils::processingAlgorithmScope	(	const QgsProcessingAlgorithm *	algorithm,
		const QVariantMap &	parameters,
		QgsProcessingContext &	context )

static

Creates a new scope which contains variables and functions relating to a processing algorithm, when used with the specified parameters and context.

For instance, algorithm name and parameter functions.

See also: processingModelAlgorithmScope()

Definition at line 946 of file qgsexpressioncontextutils.cpp.

◆ processingModelAlgorithmScope()

QgsExpressionContextScope * QgsExpressionContextUtils::processingModelAlgorithmScope	(	const QgsProcessingModelAlgorithm *	model,
		const QVariantMap &	parameters,
		QgsProcessingContext &	context )

static

Creates a new scope which contains variables and functions relating to a processing model algorithm, when used with the specified parameters and context.

For instance, model name and path variables.

Since: QGIS 3.6

Definition at line 963 of file qgsexpressioncontextutils.cpp.

◆ projectScope()

QgsExpressionContextScope * QgsExpressionContextUtils::projectScope ( const QgsProject * project )

static

Creates a new scope which contains variables and functions relating to a QGIS project.

For instance, project path and title, and variables specified through the project properties.

Parameters

project What project to use

See also: setProjectVariable()

Definition at line 316 of file qgsexpressioncontextutils.cpp.

◆ registerContextFunctions()

void QgsExpressionContextUtils::registerContextFunctions ( )

static

Registers all known core functions provided by QgsExpressionContextScope objects.

Definition at line 1001 of file qgsexpressioncontextutils.cpp.

◆ removeGlobalVariable()

void QgsExpressionContextUtils::removeGlobalVariable ( const QString & name )

static

Remove a global context variable.

Parameters

name	variable name

See also: setGlobalVariable(); setGlobalVariables(); globalScope()

Definition at line 81 of file qgsexpressioncontextutils.cpp.

◆ removeProjectVariable()

void QgsExpressionContextUtils::removeProjectVariable	(	QgsProject *	project,
		const QString &	name )

static

Remove project context variable.

Parameters

project	Project to apply changes to
name	variable name

See also: setProjectVariable(); setProjectVariables(); projectScope()

Definition at line 347 of file qgsexpressioncontextutils.cpp.

◆ setGlobalVariable()

void QgsExpressionContextUtils::setGlobalVariable	(	const QString &	name,
		const QVariant &	value )

static

Sets a global context variable.

This variable will be contained within scopes retrieved via globalScope().

Parameters

name	variable name
value	variable value

See also: setGlobalVariable(); globalScope(); removeGlobalVariable()

Definition at line 71 of file qgsexpressioncontextutils.cpp.

◆ setGlobalVariables()

void QgsExpressionContextUtils::setGlobalVariables ( const QVariantMap & variables )

static

Sets all global context variables.

Existing global variables will be removed and replaced with the variables specified.

Parameters

variables new set of global variables

See also: setGlobalVariable(); globalScope(); removeGlobalVariable()

Definition at line 76 of file qgsexpressioncontextutils.cpp.

◆ setLayerVariable()

void QgsExpressionContextUtils::setLayerVariable	(	QgsMapLayer *	layer,
		const QString &	name,
		const QVariant &	value )

static

Sets a layer context variable.

This variable will be contained within scopes retrieved via layerScope().

Parameters

layer	map layer
name	variable name
value	variable value

See also: setLayerVariables(); layerScope()

Definition at line 428 of file qgsexpressioncontextutils.cpp.

◆ setLayerVariables()

void QgsExpressionContextUtils::setLayerVariables	(	QgsMapLayer *	layer,
		const QVariantMap &	variables )

static

Sets all layer context variables.

Existing layer variables will be removed and replaced with the variables specified.

Parameters

layer	map layer
variables	new set of layer variables

See also: setLayerVariable(); layerScope()

Definition at line 454 of file qgsexpressioncontextutils.cpp.

◆ setLayoutItemVariable()

void QgsExpressionContextUtils::setLayoutItemVariable	(	QgsLayoutItem *	item,
		const QString &	name,
		const QVariant &	value )

static

Sets a layout item context variable, with the given name and value.

This variable will be contained within scopes retrieved via layoutItemScope().

See also: setLayoutItemVariables(); layoutItemScope()

Definition at line 842 of file qgsexpressioncontextutils.cpp.

◆ setLayoutItemVariables()

void QgsExpressionContextUtils::setLayoutItemVariables	(	QgsLayoutItem *	item,
		const QVariantMap &	variables )

static

Sets all layout item context variables for an item.

Existing variables will be removed and replaced with the variables specified.

See also: setLayoutItemVariable(); layoutItemScope()

Definition at line 858 of file qgsexpressioncontextutils.cpp.

◆ setLayoutMultiFrameVariable()

void QgsExpressionContextUtils::setLayoutMultiFrameVariable	(	QgsLayoutMultiFrame *	frame,
		const QString &	name,
		const QVariant &	value )

static

Sets a layout multi frame context variable, with the given name and value.

This variable will be contained within scopes retrieved via multiFrameScope().

See also: setLayoutItemVariables(); multiFrameScope()

Since: QGIS 3.10

Definition at line 903 of file qgsexpressioncontextutils.cpp.

◆ setLayoutMultiFrameVariables()

void QgsExpressionContextUtils::setLayoutMultiFrameVariables	(	QgsLayoutMultiFrame *	frame,
		const QVariantMap &	variables )

static

Sets all layout multiframe context variables for an frame.

Existing variables will be removed and replaced with the variables specified.

See also: setLayoutMultiFrameVariable(); multiFrameScope()

Since: QGIS 3.10

Definition at line 919 of file qgsexpressioncontextutils.cpp.

◆ setLayoutVariable()

void QgsExpressionContextUtils::setLayoutVariable	(	QgsLayout *	layout,
		const QString &	name,
		const QVariant &	value )

static

Sets a layout context variable.

This variable will be contained within scopes retrieved via layoutScope().

Parameters

layout	target layout
name	variable name
value	variable value

See also: setLayoutVariables(); layoutScope()

Definition at line 698 of file qgsexpressioncontextutils.cpp.

◆ setLayoutVariables()

void QgsExpressionContextUtils::setLayoutVariables	(	QgsLayout *	layout,
		const QVariantMap &	variables )

static

Sets all layout context variables.

Existing layout variables will be removed and replaced with the variables specified.

Parameters

layout	target layout
variables	new set of layer variables

See also: setLayoutVariable(); layoutScope()

Definition at line 714 of file qgsexpressioncontextutils.cpp.

◆ setProjectVariable()

void QgsExpressionContextUtils::setProjectVariable	(	QgsProject *	project,
		const QString &	name,
		const QVariant &	value )

static

Sets a project context variable.

This variable will be contained within scopes retrieved via projectScope().

Parameters

project	Project to apply changes to
name	variable name
value	variable value

See also: setProjectVariables(); removeProjectVariable(); projectScope()

Definition at line 327 of file qgsexpressioncontextutils.cpp.

◆ setProjectVariables()

void QgsExpressionContextUtils::setProjectVariables	(	QgsProject *	project,
		const QVariantMap &	variables )

static

Sets all project context variables.

Existing project variables will be removed and replaced with the variables specified.

Parameters

project	Project to apply changes to
variables	new set of project variables

See also: setProjectVariable(); removeProjectVariable(); projectScope()

Definition at line 339 of file qgsexpressioncontextutils.cpp.

◆ updateSymbolScope()

QgsExpressionContextScope * QgsExpressionContextUtils::updateSymbolScope	(	const QgsSymbol *	symbol,
		QgsExpressionContextScope *	symbolScope = nullptr )

static

Updates a symbol scope related to a QgsSymbol to an expression context.

Parameters

symbol	symbol to extract properties from
symbolScope	pointer to an existing scope to update

Definition at line 598 of file qgsexpressioncontextutils.cpp.

◆ QgsLayoutItemMap

friend class QgsLayoutItemMap

friend

Definition at line 350 of file qgsexpressioncontextutils.h.

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

/build/qgis-3.99.0+git20251207+21b3aa880ba+99sid/src/core/expression/qgsexpressioncontextutils.h
/build/qgis-3.99.0+git20251207+21b3aa880ba+99sid/src/core/expression/qgsexpressioncontextutils.cpp

Static Public Member Functions

Friends

Detailed Description

Member Function Documentation

◆ atlasScope()

◆ createFeatureBasedContext()

◆ formScope()

◆ globalProjectLayerScopes()

◆ globalScope()

◆ layerScope()

◆ layoutItemScope()

◆ layoutScope()

◆ mapLayerPositionScope()

◆ mapSettingsScope()

◆ mapToolCaptureScope()

◆ meshExpressionScope()

◆ multiFrameScope()

◆ notificationScope()

◆ parentFormScope()

◆ processingAlgorithmScope()

◆ processingModelAlgorithmScope()

◆ projectScope()

◆ registerContextFunctions()

◆ removeGlobalVariable()

◆ removeProjectVariable()

◆ setGlobalVariable()

◆ setGlobalVariables()

◆ setLayerVariable()

◆ setLayerVariables()

◆ setLayoutItemVariable()

◆ setLayoutItemVariables()

◆ setLayoutMultiFrameVariable()

◆ setLayoutMultiFrameVariables()

◆ setLayoutVariable()

◆ setLayoutVariables()

◆ setProjectVariable()

◆ setProjectVariables()

◆ updateSymbolScope()

Friends And Related Symbol Documentation

◆ QgsLayoutItemMap