A container class for data source field mapping or expression. More...

#include <qgsdatadefined.h>

Public Member Functions
	QgsDataDefined (bool active=false, bool useexpr=false, const QString &expr=QString(), const QString &field=QString())
	Construct a new data defined object. More...

	QgsDataDefined (const QgsExpression *expression)
	Construct a new data defined object, analysing the expression to determine if it's a simple field reference or an expression. More...

	QgsDataDefined (const QString &string)
	Construct a new data defined object, analysing the string to determine if it's a simple field reference or an expression. More...

	QgsDataDefined (const QgsDataDefined &other)
	Copy constructor. More...

virtual	~QgsDataDefined ()

QgsExpression *	expression ()

bool	expressionIsPrepared () const
	Returns whether the data defined object's expression is prepared. More...

QString	expressionOrField () const
	Returns an expression which represents a single field if useExpression returns false, otherwise returns the current expression string. More...

QMap< QString, QVariant >	expressionParams () const

QString	expressionString () const
	Returns the expression string of this QgsDataDefined. More...

QString	field () const
	Get the field which this QgsDataDefined represents. More...

bool	hasDefaultValues () const
	Returns whether the data defined container is set to all the default values, ie, disabled, with empty expression and no assigned field. More...

void	insertExpressionParam (const QString &key, const QVariant &param)

bool	isActive () const

bool	operator!= (const QgsDataDefined &other) const

QgsDataDefined &	operator= (QgsDataDefined const &rhs)
	Assignment operator. More...

bool	operator== (const QgsDataDefined &other) const

Q_DECL_DEPRECATED bool	prepareExpression (QgsVectorLayer *layer)
	Prepares the expression using a vector layer. More...

Q_DECL_DEPRECATED bool	prepareExpression (const QgsFields &fields)
	Prepares the expression using a fields collection. More...

bool	prepareExpression (const QgsExpressionContext &context=QgsExpressionContext())
	Prepares the expression using an expression context. More...

Q_DECL_DEPRECATED QStringList	referencedColumns (QgsVectorLayer *layer)
	Returns the columns referenced by the QgsDataDefined. More...

Q_DECL_DEPRECATED QStringList	referencedColumns (const QgsFields &fields)
	Returns the columns referenced by the QgsDataDefined. More...

QStringList	referencedColumns (const QgsExpressionContext &context=QgsExpressionContext())
	Returns the columns referenced by the QgsDataDefined. More...

void	setActive (bool active)

void	setExpressionParams (const QMap< QString, QVariant > &params)

void	setExpressionString (const QString &expr)
	Sets the expression for this QgsDataDefined. More...

void	setField (const QString &field)
	Set the field name which this QgsDataDefined represents. More...

bool	setFromXmlElement (const QDomElement &element)
	Sets the properties of the data defined container from an XML element. More...

void	setUseExpression (bool use)
	Controls if the field or the expression part is active. More...

QgsStringMap	toMap (const QString &baseName=QString()) const
	Encodes the QgsDataDefined into a string map. More...

QDomElement	toXmlElement (QDomDocument &document, const QString &elementName) const
	Returns a DOM element containing the properties of the data defined container. More...

bool	useExpression () const
	Returns if the field or the expression part is active. More...

Static Public Member Functions
static QgsDataDefined *	fromMap (const QgsStringMap &map, const QString &baseName=QString())
	Creates a QgsDataDefined from a decoded QgsStringMap. More...

Detailed Description

A container class for data source field mapping or expression.

Note: QgsDataDefined objects are implicitly shared.

Definition at line 37 of file qgsdatadefined.h.

Constructor & Destructor Documentation

◆ QgsDataDefined() [1/4]

QgsDataDefined::QgsDataDefined	(	bool	active = `false`,
		bool	useexpr = `false`,
		const QString &	expr = `QString()`,
		const QString &	field = `QString()`
	)

Construct a new data defined object.

Parameters

active	Whether the current data defined is active
useexpr	Whether to use expression instead of field
expr	Expression string
field	Field name string

Definition at line 24 of file qgsdatadefined.cpp.

◆ QgsDataDefined() [2/4]

QgsDataDefined::QgsDataDefined ( const QgsExpression * expression )

explicit

Construct a new data defined object, analysing the expression to determine if it's a simple field reference or an expression.

Parameters

expression can be null

Definition at line 32 of file qgsdatadefined.cpp.

◆ QgsDataDefined() [3/4]

QgsDataDefined::QgsDataDefined ( const QString & string )

Construct a new data defined object, analysing the string to determine if it's a simple field reference or an expression.

Parameters

string field reference or an expression, can be empty

Note: added in QGIS 2.9

Definition at line 70 of file qgsdatadefined.cpp.

◆ QgsDataDefined() [4/4]

QgsDataDefined::QgsDataDefined ( const QgsDataDefined & other )

Copy constructor.

Note that copies of data defined objects with expressions will not be prepared.

Definition at line 42 of file qgsdatadefined.cpp.

◆ ~QgsDataDefined()

QgsDataDefined::~QgsDataDefined ( )

virtual

Definition at line 82 of file qgsdatadefined.cpp.

Member Function Documentation

◆ expression()

QgsExpression * QgsDataDefined::expression ( )

Definition at line 223 of file qgsdatadefined.cpp.

◆ expressionIsPrepared()

bool QgsDataDefined::expressionIsPrepared ( ) const

Returns whether the data defined object's expression is prepared.

Returns: true if expression is prepared

Definition at line 218 of file qgsdatadefined.cpp.

◆ expressionOrField()

QString QgsDataDefined::expressionOrField ( ) const

Returns an expression which represents a single field if useExpression returns false, otherwise returns the current expression string.

Returns: An expression

Note: added in 2.12

Definition at line 140 of file qgsdatadefined.cpp.

◆ expressionParams()

QMap< QString, QVariant > QgsDataDefined::expressionParams ( ) const

Note: not available in python bindings

Definition at line 145 of file qgsdatadefined.cpp.

◆ expressionString()

QString QgsDataDefined::expressionString ( ) const

Returns the expression string of this QgsDataDefined.

Returns: An expression

See also: field(); expressionOrField()

Definition at line 122 of file qgsdatadefined.cpp.

◆ field()

QString QgsDataDefined::field ( ) const

Get the field which this QgsDataDefined represents.

Be aware that this may return a field name which may not be active if useExpression is true.

Returns: A fieldname

See also: expressionOrField()

Definition at line 273 of file qgsdatadefined.cpp.

◆ fromMap()

QgsDataDefined * QgsDataDefined::fromMap	(	const QgsStringMap &	map,
		const QString &	baseName = `QString()`
	)

static

Creates a QgsDataDefined from a decoded QgsStringMap.

Parameters

map	string map encoding of QgsDataDefined
baseName	base name for values in the string map

Returns: new QgsDataDefined if string map was successfully interpreted

See also: toMap

Note: added in QGIS 2.9

Definition at line 48 of file qgsdatadefined.cpp.

◆ hasDefaultValues()

bool QgsDataDefined::hasDefaultValues ( ) const

Returns whether the data defined container is set to all the default values, ie, disabled, with empty expression and no assigned field.

Returns: true if data defined container is set to default values

Note: added in QGIS 2.7

Definition at line 87 of file qgsdatadefined.cpp.

◆ insertExpressionParam()

void QgsDataDefined::insertExpressionParam	(	const QString &	key,
		const QVariant &	param
	)

Definition at line 289 of file qgsdatadefined.cpp.

◆ isActive()

bool QgsDataDefined::isActive ( ) const

Definition at line 92 of file qgsdatadefined.cpp.

◆ operator!=()

bool QgsDataDefined::operator!= ( const QgsDataDefined & other ) const

Definition at line 344 of file qgsdatadefined.cpp.

◆ operator=()

QgsDataDefined & QgsDataDefined::operator= ( QgsDataDefined const & rhs )

Assignment operator.

Note that after assignment the data defined object's expression will not be prepared.

Definition at line 349 of file qgsdatadefined.cpp.

◆ operator==()

bool QgsDataDefined::operator== ( const QgsDataDefined & other ) const

Definition at line 339 of file qgsdatadefined.cpp.

◆ prepareExpression() [1/3]

bool QgsDataDefined::prepareExpression ( QgsVectorLayer * layer )

Prepares the expression using a vector layer.

Parameters

layer vector layer

Returns: true if expression was successfully prepared

Deprecated:: use QgsExpressionContext variant instead

Definition at line 156 of file qgsdatadefined.cpp.

◆ prepareExpression() [2/3]

bool QgsDataDefined::prepareExpression ( const QgsFields & fields )

Prepares the expression using a fields collection.

Parameters

fields

Returns: true if expression was successfully prepared

Note: added in QGIS 2.9

Deprecated:: use QgsExpressionContext variant instead

Definition at line 170 of file qgsdatadefined.cpp.

◆ prepareExpression() [3/3]

bool QgsDataDefined::prepareExpression ( const QgsExpressionContext & context = QgsExpressionContext() )

Prepares the expression using an expression context.

Parameters

context expression context

Returns: true if expression was successfully prepared

Note: added in QGIS 2.12

Definition at line 175 of file qgsdatadefined.cpp.

◆ referencedColumns() [1/3]

QStringList QgsDataDefined::referencedColumns ( QgsVectorLayer * layer )

Returns the columns referenced by the QgsDataDefined.

Parameters

layer vector layer, used for preparing the expression if required

Deprecated:: use QgsExpressionContext variant instead

Definition at line 232 of file qgsdatadefined.cpp.

◆ referencedColumns() [2/3]

QStringList QgsDataDefined::referencedColumns ( const QgsFields & fields )

Returns the columns referenced by the QgsDataDefined.

Parameters

fields vector layer, used for preparing the expression if required

Note: added in QGIS 2.9

Deprecated:: use QgsExpressionContext variant instead

Definition at line 245 of file qgsdatadefined.cpp.

◆ referencedColumns() [3/3]

QStringList QgsDataDefined::referencedColumns ( const QgsExpressionContext & context = QgsExpressionContext() )

Returns the columns referenced by the QgsDataDefined.

Parameters

context expression context, used for preparing the expression if required

Note: added in QGIS 2.12

Definition at line 250 of file qgsdatadefined.cpp.

◆ setActive()

void QgsDataDefined::setActive ( bool active )

Definition at line 97 of file qgsdatadefined.cpp.

◆ setExpressionParams()

void QgsDataDefined::setExpressionParams ( const QMap< QString, QVariant > & params )

Note: not available in python bindings

Definition at line 150 of file qgsdatadefined.cpp.

◆ setExpressionString()

void QgsDataDefined::setExpressionString ( const QString & expr )

Sets the expression for this QgsDataDefined.

Will also set useExpression to true.

Parameters

expr	The expression to set

See also: setField

Definition at line 127 of file qgsdatadefined.cpp.

◆ setField()

void QgsDataDefined::setField ( const QString & field )

Set the field name which this QgsDataDefined represents.

Will set useExpression to false.

Parameters

field

Definition at line 278 of file qgsdatadefined.cpp.

◆ setFromXmlElement()

bool QgsDataDefined::setFromXmlElement ( const QDomElement & element )

Sets the properties of the data defined container from an XML element.

Calling this will overwrite all the current properties of the container.

Parameters

element DOM element

Returns: true if properties were successfully read from element

Note: added in QGIS 2.7

See also: toXmlElement

Definition at line 322 of file qgsdatadefined.cpp.

◆ setUseExpression()

void QgsDataDefined::setUseExpression ( bool use )

Controls if the field or the expression part is active.

For QGIS<=2.10 it is mandatory to call this after setExpressionString or setField.

Parameters

use	True if it should be set to expression mode.

Definition at line 111 of file qgsdatadefined.cpp.

◆ toMap()

QgsStringMap QgsDataDefined::toMap ( const QString & baseName = QString() ) const

Encodes the QgsDataDefined into a string map.

Parameters

baseName optional base name for values in the string map. Can be used to differentiate multiple QgsDataDefineds encoded in the same string map.

See also: fromMap

Definition at line 295 of file qgsdatadefined.cpp.

◆ toXmlElement()

QDomElement QgsDataDefined::toXmlElement	(	QDomDocument &	document,
		const QString &	elementName
	)		const

Returns a DOM element containing the properties of the data defined container.

Parameters

document	DOM document
elementName	name for DOM element

Returns: DOM element corresponding to data defined container

Note: added in QGIS 2.7

See also: setFromXmlElement

Definition at line 312 of file qgsdatadefined.cpp.

◆ useExpression()

bool QgsDataDefined::useExpression ( ) const

Returns if the field or the expression part is active.

Returns: True if it is in expression mode.

Definition at line 106 of file qgsdatadefined.cpp.

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

/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsdatadefined.h
/tmp/buildd/qgis-2.18.21+99unstable/src/core/qgsdatadefined.cpp

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ QgsDataDefined() [1/4]

◆ QgsDataDefined() [2/4]

◆ QgsDataDefined() [3/4]

◆ QgsDataDefined() [4/4]

◆ ~QgsDataDefined()

Member Function Documentation

◆ expression()

◆ expressionIsPrepared()

◆ expressionOrField()

◆ expressionParams()

◆ expressionString()

◆ field()

◆ fromMap()

◆ hasDefaultValues()

◆ insertExpressionParam()

◆ isActive()

◆ operator!=()

◆ operator=()

◆ operator==()

◆ prepareExpression() [1/3]

◆ prepareExpression() [2/3]

◆ prepareExpression() [3/3]

◆ referencedColumns() [1/3]

◆ referencedColumns() [2/3]

◆ referencedColumns() [3/3]

◆ setActive()

◆ setExpressionParams()

◆ setExpressionString()

◆ setField()

◆ setFromXmlElement()

◆ setUseExpression()

◆ toMap()

◆ toXmlElement()

◆ useExpression()