An expression parameter for processing algorithms. More...

#include <qgsprocessingparameters.h>

Inheritance diagram for QgsProcessingParameterExpression:

Public Member Functions
	QgsProcessingParameterExpression (const QString &name, const QString &description=QString(), const QVariant &defaultValue=QVariant(), const QString &parentLayerParameterName=QString(), bool optional=false, Qgis::ExpressionType type=Qgis::ExpressionType::Qgis)
	Constructor for QgsProcessingParameterExpression.

QString	asPythonString (QgsProcessing::PythonOutputType outputType=QgsProcessing::PythonOutputType::PythonQgsProcessingAlgorithmSubclass) const override
	Returns the parameter definition as a Python command which can be used within a Python Processing script.

QgsProcessingParameterDefinition *	clone () const override
	Creates a clone of the parameter definition.

QStringList	dependsOnOtherParameters () const override
	Returns a list of other parameter names on which this parameter is dependent (e.g.

Qgis::ExpressionType	expressionType () const
	Returns the parameter's expression type.

bool	fromVariantMap (const QVariantMap &map) override
	Restores this parameter to a QVariantMap.

QString	parentLayerParameterName () const
	Returns the name of the parent layer parameter, or an empty string if this is not set.

void	setExpressionType (Qgis::ExpressionType type)
	Sets the parameter's expression type.

void	setParentLayerParameterName (const QString &parentLayerParameterName)
	Sets the name of the parent layer parameter.

QVariantMap	toVariantMap () const override
	Saves this parameter to a QVariantMap.

QString	type () const override
	Unique parameter type name.

QString	valueAsPythonString (const QVariant &value, QgsProcessingContext &context) const override
	Returns a string version of the parameter input value, which is suitable for use as an input parameter value when running an algorithm directly from a Python command.

Public Member Functions inherited from QgsProcessingParameterDefinition
	QgsProcessingParameterDefinition (const QString &name, const QString &description=QString(), const QVariant &defaultValue=QVariant(), bool optional=false, const QString &help=QString())
	Constructor for QgsProcessingParameterDefinition.

virtual	~QgsProcessingParameterDefinition ()=default

QStringList	additionalExpressionContextVariables () const
	Returns a list of additional expression context variables which are available for use when evaluating this parameter.

QgsProcessingAlgorithm *	algorithm () const
	Returns a pointer to the algorithm which owns this parameter.

virtual QString	asScriptCode () const
	Returns the parameter definition encoded in a string which can be used within a Processing script.

virtual bool	checkValueIsAcceptable (const QVariant &input, QgsProcessingContext *context=nullptr) const
	Checks whether the specified input value is acceptable for the parameter.

QVariant	defaultValue () const
	Returns the default value for the parameter.

QVariant	defaultValueForGui () const
	Returns the default value to use for the parameter in a GUI.

QString	description () const
	Returns the description for the parameter.

QString	dynamicLayerParameterName () const
	Returns the name of the parameter for a layer linked to a dynamic parameter, or an empty string if this is not set.

QgsPropertyDefinition	dynamicPropertyDefinition () const
	Returns the property definition for dynamic properties.

Qgis::ProcessingParameterFlags	flags () const
	Returns any flags associated with the parameter.

QVariant	guiDefaultValueOverride () const
	Returns the default value to use in the GUI for the parameter.

QString	help () const
	Returns the help for the parameter.

virtual bool	isDestination () const
	Returns `true` if this parameter represents a file or layer destination, e.g.

bool	isDynamic () const
	Returns `true` if the parameter supports is dynamic, and can support data-defined values (i.e.

QVariantMap &	metadata ()
	Returns the parameter's freeform metadata.

QVariantMap	metadata () const
	Returns the parameter's freeform metadata.

QString	name () const
	Returns the name of the parameter.

QgsProcessingProvider *	provider () const
	Returns a pointer to the provider for the algorithm which owns this parameter.

void	setAdditionalExpressionContextVariables (const QStringList &variables)
	Sets a list of additional expression context variables which are available for use when evaluating this parameter.

void	setDefaultValue (const QVariant &value)
	Sets the default value for the parameter.

void	setDescription (const QString &description)
	Sets the description for the parameter.

void	setDynamicLayerParameterName (const QString &name)
	Sets the name for the parameter for a layer linked to a dynamic parameter, or an empty string if this is not set.

void	setDynamicPropertyDefinition (const QgsPropertyDefinition &definition)
	Sets the property definition for dynamic properties.

void	setFlags (Qgis::ProcessingParameterFlags flags)
	Sets the flags associated with the parameter.

void	setGuiDefaultValueOverride (const QVariant &value)
	Sets the default value to use for the parameter in GUI widgets.

void	setHelp (const QString &help)
	Sets the help for the parameter.

void	setIsDynamic (bool dynamic)
	Sets whether the parameter is dynamic, and can support data-defined values (i.e.

void	setMetadata (const QVariantMap &metadata)
	Sets the parameter's freeform metadata.

void	setName (const QString &name)
	Sets the name of the parameter.

virtual QString	toolTip () const
	Returns a formatted tooltip for use with the parameter, which gives helpful information like parameter description, ID, and extra content like default values (depending on parameter type).

virtual QVariant	valueAsJsonObject (const QVariant &value, QgsProcessingContext &context) const
	Returns a version of the parameter input value, which is suitable for use in a JSON object.

virtual QString	valueAsPythonComment (const QVariant &value, QgsProcessingContext &context) const
	Returns a Python comment explaining a parameter value, or an empty string if no comment is required.

virtual QString	valueAsString (const QVariant &value, QgsProcessingContext &context, bool &ok) const
	Returns a string version of the parameter input value (if possible).

virtual QStringList	valueAsStringList (const QVariant &value, QgsProcessingContext &context, bool &ok) const
	Returns a string list version of the parameter input value (if possible).

Static Public Member Functions
static QgsProcessingParameterExpression *	fromScriptCode (const QString &name, const QString &description, bool isOptional, const QString &definition)
	Creates a new parameter using the definition from a script code.

static QString	typeName ()
	Returns the type name for the parameter class.

Additional Inherited Members
Public Types inherited from QgsProcessingParameterDefinition
enum class	ValueAsStringFlag : int { AllowMapLayerValues = 1 << 0 }
	Flags for passing to the valueAsStringPrivate() method. More...

typedef QFlags< ValueAsStringFlag >	ValueAsStringFlags

Protected Member Functions inherited from QgsProcessingParameterDefinition
QVariant	defaultGuiValueFromSetting () const
	Default gui value for an algorithm parameter from settings.

QVariant	valueAsJsonObjectPrivate (const QVariant &value, QgsProcessingContext &context, ValueAsStringFlags flags) const
	Internal method for evaluating values as JSON objects.

QString	valueAsStringPrivate (const QVariant &value, QgsProcessingContext &context, bool &ok, ValueAsStringFlags flags) const
	Internal method for evaluating values as string.

Protected Attributes inherited from QgsProcessingParameterDefinition
QStringList	mAdditionalExpressionVariables
	Additional expression context variables exposed for use by this parameter.

QgsProcessingAlgorithm *	mAlgorithm = nullptr
	Pointer to algorithm which owns this parameter.

QVariant	mDefault
	Default value for parameter.

QString	mDescription
	Parameter description.

QString	mDynamicLayerParameterName
	Linked vector layer parameter name for dynamic properties.

Qgis::ProcessingParameterFlags	mFlags
	Parameter flags.

QVariant	mGuiDefault
	Default value for parameter in GUI.

QString	mHelp
	Parameter help.

bool	mIsDynamic = false
	True for dynamic parameters, which can have data-defined (QgsProperty) based values.

QVariantMap	mMetadata
	Freeform metadata for parameter. Mostly used by widget wrappers to customize their appearance and behavior.

QString	mName
	Parameter name.

QgsPropertyDefinition	mPropertyDefinition
	Data defined property definition.

Detailed Description

An expression parameter for processing algorithms.

Definition at line 2959 of file qgsprocessingparameters.h.

Constructor & Destructor Documentation

◆ QgsProcessingParameterExpression()

QgsProcessingParameterExpression::QgsProcessingParameterExpression	(	const QString &	name,
		const QString &	description = `QString()`,
		const QVariant &	defaultValue = `QVariant()`,
		const QString &	parentLayerParameterName = `QString()`,
		bool	optional = `false`,
		Qgis::ExpressionType	type = `Qgis::ExpressionType::Qgis`
	)

Constructor for QgsProcessingParameterExpression.

Definition at line 5495 of file qgsprocessingparameters.cpp.

Member Function Documentation

◆ asPythonString()

QString QgsProcessingParameterExpression::asPythonString ( QgsProcessing::PythonOutputType outputType = QgsProcessing::PythonOutputType::PythonQgsProcessingAlgorithmSubclass ) const

overridevirtual

Returns the parameter definition as a Python command which can be used within a Python Processing script.

The outputType argument specifies the desired output format for the Python string, i.e. the intended end use of the generated Python code.

Since: QGIS 3.6

Reimplemented from QgsProcessingParameterDefinition.

Definition at line 5528 of file qgsprocessingparameters.cpp.

◆ clone()

QgsProcessingParameterDefinition * QgsProcessingParameterExpression::clone ( ) const

overridevirtual

Creates a clone of the parameter definition.

Implements QgsProcessingParameterDefinition.

Definition at line 5503 of file qgsprocessingparameters.cpp.

◆ dependsOnOtherParameters()

QStringList QgsProcessingParameterExpression::dependsOnOtherParameters ( ) const

overridevirtual

Returns a list of other parameter names on which this parameter is dependent (e.g.

field parameters which depend on a parent layer parameter).

Reimplemented from QgsProcessingParameterDefinition.

Definition at line 5520 of file qgsprocessingparameters.cpp.

◆ expressionType()

Qgis::ExpressionType QgsProcessingParameterExpression::expressionType ( ) const

Returns the parameter's expression type.

See also: setExpressionType()

Since: QGIS 3.32

Definition at line 5573 of file qgsprocessingparameters.cpp.

◆ fromScriptCode()

QgsProcessingParameterExpression * QgsProcessingParameterExpression::fromScriptCode	(	const QString &	name,
		const QString &	description,
		bool	isOptional,
		const QString &	definition
	)

static

Creates a new parameter using the definition from a script code.

Definition at line 5599 of file qgsprocessingparameters.cpp.

◆ fromVariantMap()

bool QgsProcessingParameterExpression::fromVariantMap ( const QVariantMap & map )

overridevirtual

Restores this parameter to a QVariantMap.

Subclasses should ensure that they call the base class method.

See also: toVariantMap()

Reimplemented from QgsProcessingParameterDefinition.

Definition at line 5591 of file qgsprocessingparameters.cpp.

◆ parentLayerParameterName()

QString QgsProcessingParameterExpression::parentLayerParameterName ( ) const

Returns the name of the parent layer parameter, or an empty string if this is not set.

See also: setParentLayerParameterName()

Definition at line 5563 of file qgsprocessingparameters.cpp.

◆ setExpressionType()

void QgsProcessingParameterExpression::setExpressionType ( Qgis::ExpressionType type )

Sets the parameter's expression type.

See also: expressionType()

Since: QGIS 3.32

Definition at line 5578 of file qgsprocessingparameters.cpp.

◆ setParentLayerParameterName()

void QgsProcessingParameterExpression::setParentLayerParameterName ( const QString & parentLayerParameterName )

Sets the name of the parent layer parameter.

Use an empty string if this is not required.

See also: parentLayerParameterName()

Definition at line 5568 of file qgsprocessingparameters.cpp.

◆ toVariantMap()

QVariantMap QgsProcessingParameterExpression::toVariantMap ( ) const

overridevirtual

Saves this parameter to a QVariantMap.

Subclasses should ensure that they call the base class method and then extend the result with additional properties.

See also: fromVariantMap()

Reimplemented from QgsProcessingParameterDefinition.

Definition at line 5583 of file qgsprocessingparameters.cpp.

◆ type()

QString QgsProcessingParameterExpression::type ( ) const

inlineoverridevirtual

Unique parameter type name.

Implements QgsProcessingParameterDefinition.

Definition at line 2975 of file qgsprocessingparameters.h.

◆ typeName()

static QString QgsProcessingParameterExpression::typeName ( )

inlinestatic

Returns the type name for the parameter class.

Definition at line 2973 of file qgsprocessingparameters.h.

◆ valueAsPythonString()

QString QgsProcessingParameterExpression::valueAsPythonString	(	const QVariant &	value,
		QgsProcessingContext &	context
	)		const

overridevirtual

Returns a string version of the parameter input value, which is suitable for use as an input parameter value when running an algorithm directly from a Python command.

See also: valueAsJsonObject(); valueAsString()

Reimplemented from QgsProcessingParameterDefinition.

Definition at line 5508 of file qgsprocessingparameters.cpp.

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

/build/qgis-3.41.0+git20241225+af5edcb665c+99sid/src/core/processing/qgsprocessingparameters.h
/build/qgis-3.41.0+git20241225+af5edcb665c+99sid/src/core/processing/qgsprocessingparameters.cpp

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ QgsProcessingParameterExpression()

Member Function Documentation

◆ asPythonString()

◆ clone()

◆ dependsOnOtherParameters()

◆ expressionType()

◆ fromScriptCode()

◆ fromVariantMap()

◆ parentLayerParameterName()

◆ setExpressionType()

◆ setParentLayerParameterName()

◆ toVariantMap()

◆ type()

◆ typeName()

◆ valueAsPythonString()