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

#include <qgsexpressioncontext.h>

Static Public Member Functions
static QgsExpressionContextScope *	atlasScope (QgsLayoutAtlas *atlas)
	Creates a new scope which contains variables and functions relating to a QgsLayoutAtlas. More...

static QgsExpressionContext	createFeatureBasedContext (const QgsFeature &feature, const QgsFields &fields)
	Helper function for creating an expression context which contains just a feature and fields collection. More...

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 feature. More...

static QList< QgsExpressionContextScope * >	globalProjectLayerScopes (const QgsMapLayer *layer)
	Creates a list of three scopes: global, layer's project and layer. More...

static QgsExpressionContextScope *	globalScope ()
	Creates a new scope which contains variables and functions relating to the global QGIS context. More...

static QgsExpressionContextScope *	layerScope (const QgsMapLayer *layer)
	Creates a new scope which contains variables and functions relating to a QgsMapLayer. More...

static QgsExpressionContextScope *	layoutItemScope (const QgsLayoutItem *item)
	Creates a new scope which contains variables and functions relating to a QgsLayoutItem. More...

static QgsExpressionContextScope *	layoutScope (const QgsLayout *layout)
	Creates a new scope which contains variables and functions relating to a QgsLayout layout. More...

static QgsExpressionContextScope *	mapSettingsScope (const QgsMapSettings &mapSettings)
	Creates a new scope which contains variables and functions relating to a QgsMapSettings object. More...

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. More...

static QgsExpressionContextScope *	notificationScope (const QString &message=QString())
	Creates a new scope which contains variables and functions relating to provider notifications. More...

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. More...

static QgsExpressionContextScope *	projectScope (const QgsProject *project)
	Creates a new scope which contains variables and functions relating to a QGIS project. More...

static void	registerContextFunctions ()
	Registers all known core functions provided by QgsExpressionContextScope objects. More...

static void	removeGlobalVariable (const QString &name)
	Remove a global context variable. More...

static void	removeProjectVariable (QgsProject *project, const QString &name)
	Remove project context variable. More...

static void	setGlobalVariable (const QString &name, const QVariant &value)
	Sets a global context variable. More...

static void	setGlobalVariables (const QVariantMap &variables)
	Sets all global context variables. More...

static void	setLayerVariable (QgsMapLayer *layer, const QString &name, const QVariant &value)
	Sets a layer context variable. More...

static void	setLayerVariables (QgsMapLayer *layer, const QVariantMap &variables)
	Sets all layer context variables. More...

static void	setLayoutItemVariable (QgsLayoutItem *item, const QString &name, const QVariant &value)
	Sets a layout item context variable, with the given name and value. More...

static void	setLayoutItemVariables (QgsLayoutItem *item, const QVariantMap &variables)
	Sets all layout item context variables for an item. More...

static void	setLayoutVariable (QgsLayout *layout, const QString &name, const QVariant &value)
	Sets a layout context variable. More...

static void	setLayoutVariables (QgsLayout *layout, const QVariantMap &variables)
	Sets all layout context variables. More...

static void	setProjectVariable (QgsProject *project, const QString &name, const QVariant &value)
	Sets a project context variable. More...

static void	setProjectVariables (QgsProject *project, const QVariantMap &variables)
	Sets all project context variables. More...

static QgsExpressionContextScope *	updateSymbolScope (const QgsSymbol symbol, QgsExpressionContextScope symbolScope=nullptr)
	Updates a symbol scope related to a QgsSymbol to an expression context. More...

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).

Since: QGIS 2.12

Definition at line 756 of file qgsexpressioncontext.h.

Member Function Documentation

QgsExpressionContextScope * QgsExpressionContextUtils::atlasScope ( 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 null, a set of default atlas variables will be added to the scope.

Definition at line 1159 of file qgsexpressioncontext.cpp.

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 1280 of file qgsexpressioncontext.cpp.

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 feature.

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 769 of file qgsexpressioncontext.cpp.

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

static

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

Since: QGIS 3.0

Definition at line 908 of file qgsexpressioncontext.cpp.

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 582 of file qgsexpressioncontext.cpp.

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 866 of file qgsexpressioncontext.cpp.

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()

Since: QGIS 3.0

Definition at line 1198 of file qgsexpressioncontext.cpp.

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.

Since: QGIS 3.0

Definition at line 1066 of file qgsexpressioncontext.cpp.

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 958 of file qgsexpressioncontext.cpp.

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.

Since: QGIS 3.0

Definition at line 1024 of file qgsexpressioncontext.cpp.

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 1305 of file qgsexpressioncontext.cpp.

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.

Definition at line 1288 of file qgsexpressioncontext.cpp.

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 779 of file qgsexpressioncontext.cpp.

void QgsExpressionContextUtils::registerContextFunctions ( )

static

Registers all known core functions provided by QgsExpressionContextScope objects.

Definition at line 1312 of file qgsexpressioncontext.cpp.

void QgsExpressionContextUtils::removeGlobalVariable ( const QString & name )

static

Remove a global context variable.

Parameters

name	variable name

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

Definition at line 617 of file qgsexpressioncontext.cpp.

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 854 of file qgsexpressioncontext.cpp.

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 607 of file qgsexpressioncontext.cpp.

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 612 of file qgsexpressioncontext.cpp.

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 923 of file qgsexpressioncontext.cpp.

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 939 of file qgsexpressioncontext.cpp.

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()

Since: QGIS 3.0

Definition at line 1245 of file qgsexpressioncontext.cpp.

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()

Since: QGIS 3.0

Definition at line 1261 of file qgsexpressioncontext.cpp.

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()

Since: QGIS 3.0

Definition at line 1124 of file qgsexpressioncontext.cpp.

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()

Since: QGIS 3.0

Definition at line 1140 of file qgsexpressioncontext.cpp.

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 834 of file qgsexpressioncontext.cpp.

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 846 of file qgsexpressioncontext.cpp.

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

Since: QGIS 2.14

Definition at line 1048 of file qgsexpressioncontext.cpp.

Friends And Related Function Documentation

friend class QgsLayoutItemMap

friend

Definition at line 1006 of file qgsexpressioncontext.h.

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

/build/qgis-3.4.15+24xenial/src/core/qgsexpressioncontext.h
/build/qgis-3.4.15+24xenial/src/core/qgsexpressioncontext.cpp

Static Public Member Functions

Friends

Detailed Description

Member Function Documentation

Friends And Related Function Documentation