The QgsFieldExpressionWidget class reates a widget to choose fields and edit expressions It contains a combo boxto display the fields and expression and a button to open the expression dialog. More...

#include <qgsfieldexpressionwidget.h>

Inheritance diagram for QgsFieldExpressionWidget:

[legend]

Public Slots
void	setExpression (const QString &expression)
	Sets the current expression text and if applicable also the field. More...

void	setField (const QString &fieldName)
	sets the current field or expression in the widget More...

void	setLayer (QgsMapLayer *layer)
	Sets the layer used to display the fields and expression. More...

void	setRow (int row)
	sets the current row in the widget More...

Signals
void	allowEvalErrorsChanged ()
	Allow accepting expressions with evaluation errors. More...

void	fieldChanged (const QString &fieldName)
	Emitted when the currently selected field changes. More...

void	fieldChanged (const QString &fieldName, bool isValid)
	fieldChanged signal with indication of the validity of the expression More...

Public Member Functions
	QgsFieldExpressionWidget (QWidget *parent=nullptr)
	QgsFieldExpressionWidget creates a widget with a combo box to display the fields and expression and a button to open the expression dialog. More...

bool	allowEmptyFieldName () const
	Returns `true` if the combo box allows the empty field ("not set") choice. More...

bool	allowEvalErrors () const
	Allow accepting expressions with evaluation errors. More...

void	appendScope (QgsExpressionContextScope *scope)
	Appends a scope to the current expression context. More...

QString	asExpression () const
	Returns the currently selected field or expression. More...

QString	currentField (bool isExpression=nullptr, bool isValid=nullptr) const
	currentField returns the currently selected field or expression if allowed More...

QString	currentText () const
	Returns the current text that is set in the expression area. More...

QString	expression () const
	Returns the currently selected field or expression. More...

const QString	expressionDialogTitle ()
	Returns the title used for the expression dialog. More...

QgsFieldProxyModel::Filters	filters () const
	currently used filter on list of fields More...

bool	isExpression () const
	If the content is not just a simple field this method will return `true`. More...

bool	isValidExpression (QString *expressionError=nullptr) const
	Returns `true` if the current expression is valid. More...

QgsVectorLayer *	layer () const
	Returns the layer currently associated with the widget. More...

void	registerExpressionContextGenerator (const QgsExpressionContextGenerator *generator)
	Register an expression context generator class that will be used to retrieve an expression context for the widget. More...

void	setAllowEmptyFieldName (bool allowEmpty)
	Sets whether an optional empty field ("not set") option is shown in the combo box. More...

void	setAllowEvalErrors (bool allowEvalErrors)
	Allow accepting expressions with evaluation errors. More...

void	setExpressionDialogTitle (const QString &title)
	define the title used in the expression dialog More...

void	setFilters (QgsFieldProxyModel::Filters filters)
	setFilters allows fitering according to the type of field More...

void	setGeomCalculator (const QgsDistanceArea &da)
	Sets the geometry calculator used in the expression dialog. More...

void	setLeftHandButtonStyle (bool isLeft)

Protected Slots
void	currentFieldChanged ()

void	editExpression ()
	open the expression dialog to edit the current or add a new expression More...

void	expressionEdited (const QString &expression)
	when expression is edited by the user in the line edit, it will be checked for validity More...

void	expressionEditingFinished ()
	when expression has been edited (finished) it will be added to the model More...

bool	isExpressionValid (const QString &expressionStr)

void	updateLineEditStyle (const QString &expression=QString())
	updateLineEditStyle will re-style (color/font) the line edit depending on content and status More...

Protected Member Functions
void	changeEvent (QEvent *event) override

bool	eventFilter (QObject watched, QEvent event) override

Properties
bool	allowEmptyFieldName

bool	allowEvalErrors

QString	expressionDialogTitle

QgsFieldProxyModel::Filters	filters

Friends
class	TestQgsFieldExpressionWidget

Detailed Description

The QgsFieldExpressionWidget class reates a widget to choose fields and edit expressions It contains a combo boxto display the fields and expression and a button to open the expression dialog.

The combo box is editable, allowing expressions to be edited inline. The validity of the expression is checked live on key press, invalid expressions are displayed in red. The expression will be added to the model (and the fieldChanged signals emitted) only when editing in the line edit is finished (focus lost, enter key pressed).

Definition at line 46 of file qgsfieldexpressionwidget.h.

Constructor & Destructor Documentation

◆ QgsFieldExpressionWidget()

QgsFieldExpressionWidget::QgsFieldExpressionWidget ( QWidget * parent = nullptr )

explicit

QgsFieldExpressionWidget creates a widget with a combo box to display the fields and expression and a button to open the expression dialog.

Definition at line 32 of file qgsfieldexpressionwidget.cpp.

Member Function Documentation

◆ allowEmptyFieldName()

bool QgsFieldExpressionWidget::allowEmptyFieldName ( ) const

Returns true if the combo box allows the empty field ("not set") choice.

See also: setAllowEmptyFieldName()

Since: QGIS 3.4.6

◆ allowEvalErrors()

bool QgsFieldExpressionWidget::allowEvalErrors ( ) const

Allow accepting expressions with evaluation errors.

This can be useful when we are not able to provide an expression context of which we are sure it's completely populated.

Since: QGIS 3.0

◆ allowEvalErrorsChanged

void QgsFieldExpressionWidget::allowEvalErrorsChanged ( )

signal

Allow accepting expressions with evaluation errors.

This can be useful when we are not able to provide an expression context of which we are sure it's completely populated.

Since: QGIS 3.0

◆ appendScope()

void QgsFieldExpressionWidget::appendScope ( QgsExpressionContextScope * scope )

Appends a scope to the current expression context.

Parameters

scope The scope to add.

Since: QGIS 3.2

Definition at line 377 of file qgsfieldexpressionwidget.cpp.

◆ asExpression()

QString QgsFieldExpressionWidget::asExpression ( ) const

Returns the currently selected field or expression.

If a field is currently selected, the returned value will be converted to a valid expression referencing this field (ie enclosing the field name with appropriate quotations).

Since: QGIS 2.14

Definition at line 123 of file qgsfieldexpressionwidget.cpp.

◆ changeEvent()

void QgsFieldExpressionWidget::changeEvent ( QEvent * event )

overrideprotected

Definition at line 264 of file qgsfieldexpressionwidget.cpp.

◆ currentField()

QString QgsFieldExpressionWidget::currentField	(	bool *	isExpression = `nullptr`,
		bool *	isValid = `nullptr`
	)		const

currentField returns the currently selected field or expression if allowed

Parameters

isExpression	determines if the string returned is the name of a field or an expression
isValid	determines if the expression (or field) returned is valid

Definition at line 144 of file qgsfieldexpressionwidget.cpp.

◆ currentFieldChanged

void QgsFieldExpressionWidget::currentFieldChanged ( )

protectedslot

Definition at line 317 of file qgsfieldexpressionwidget.cpp.

◆ currentText()

QString QgsFieldExpressionWidget::currentText ( ) const

Returns the current text that is set in the expression area.

Definition at line 118 of file qgsfieldexpressionwidget.cpp.

◆ editExpression

void QgsFieldExpressionWidget::editExpression ( )

protectedslot

open the expression dialog to edit the current or add a new expression

Definition at line 226 of file qgsfieldexpressionwidget.cpp.

◆ eventFilter()

bool QgsFieldExpressionWidget::eventFilter	(	QObject *	watched,
		QEvent *	event
	)

overrideprotected

Definition at line 289 of file qgsfieldexpressionwidget.cpp.

◆ expression()

QString QgsFieldExpressionWidget::expression ( ) const

Returns the currently selected field or expression.

If a field is currently selected, the returned value will be converted to a valid expression referencing this field (ie enclosing the field name with appropriate quotations).

Alias for asExpression()

Since: QGIS 3.0

Definition at line 128 of file qgsfieldexpressionwidget.cpp.

◆ expressionDialogTitle()

const QString QgsFieldExpressionWidget::expressionDialogTitle ( )

inline

Returns the title used for the expression dialog.

Definition at line 74 of file qgsfieldexpressionwidget.h.

◆ expressionEdited

void QgsFieldExpressionWidget::expressionEdited ( const QString & expression )

protectedslot

when expression is edited by the user in the line edit, it will be checked for validity

Definition at line 248 of file qgsfieldexpressionwidget.cpp.

◆ expressionEditingFinished

void QgsFieldExpressionWidget::expressionEditingFinished ( )

protectedslot

when expression has been edited (finished) it will be added to the model

Definition at line 254 of file qgsfieldexpressionwidget.cpp.

◆ fieldChanged [1/2]

void QgsFieldExpressionWidget::fieldChanged ( const QString & fieldName )

signal

Emitted when the currently selected field changes.

◆ fieldChanged [2/2]

void QgsFieldExpressionWidget::fieldChanged	(	const QString &	fieldName,
		bool	isValid
	)

signal

fieldChanged signal with indication of the validity of the expression

◆ filters()

QgsFieldProxyModel::Filters QgsFieldExpressionWidget::filters ( ) const

inline

currently used filter on list of fields

Definition at line 96 of file qgsfieldexpressionwidget.h.

◆ isExpression()

bool QgsFieldExpressionWidget::isExpression ( ) const

If the content is not just a simple field this method will return true.

Definition at line 139 of file qgsfieldexpressionwidget.cpp.

◆ isExpressionValid

bool QgsFieldExpressionWidget::isExpressionValid ( const QString & expressionStr )

protectedslot

Definition at line 370 of file qgsfieldexpressionwidget.cpp.

◆ isValidExpression()

bool QgsFieldExpressionWidget::isValidExpression ( QString * expressionError = nullptr ) const

Returns true if the current expression is valid.

Definition at line 133 of file qgsfieldexpressionwidget.cpp.

◆ layer()

QgsVectorLayer * QgsFieldExpressionWidget::layer ( ) const

Returns the layer currently associated with the widget.

See also: setLayer()

Definition at line 160 of file qgsfieldexpressionwidget.cpp.

◆ registerExpressionContextGenerator()

void QgsFieldExpressionWidget::registerExpressionContextGenerator ( const QgsExpressionContextGenerator * generator )

Register an expression context generator class that will be used to retrieve an expression context for the widget.

Parameters

generator A QgsExpressionContextGenerator class that will be used to create an expression context when required.

Since: QGIS 3.0

Definition at line 165 of file qgsfieldexpressionwidget.cpp.

◆ setAllowEmptyFieldName()

void QgsFieldExpressionWidget::setAllowEmptyFieldName ( bool allowEmpty )

Sets whether an optional empty field ("not set") option is shown in the combo box.

See also: allowEmptyFieldName()

Since: QGIS 3.4.6

Definition at line 87 of file qgsfieldexpressionwidget.cpp.

◆ setAllowEvalErrors()

void QgsFieldExpressionWidget::setAllowEvalErrors ( bool allowEvalErrors )

Allow accepting expressions with evaluation errors.

This can be useful when we are not able to provide an expression context of which we are sure it's completely populated.

Since: QGIS 3.0

Definition at line 308 of file qgsfieldexpressionwidget.cpp.

◆ setExpression

void QgsFieldExpressionWidget::setExpression ( const QString & expression )

slot

Sets the current expression text and if applicable also the field.

Alias for setField.

Since: QGIS 3.0

Definition at line 221 of file qgsfieldexpressionwidget.cpp.

◆ setExpressionDialogTitle()

void QgsFieldExpressionWidget::setExpressionDialogTitle ( const QString & title )

define the title used in the expression dialog

Definition at line 77 of file qgsfieldexpressionwidget.cpp.

◆ setField

void QgsFieldExpressionWidget::setField ( const QString & fieldName )

slot

sets the current field or expression in the widget

Definition at line 188 of file qgsfieldexpressionwidget.cpp.

◆ setFilters()

void QgsFieldExpressionWidget::setFilters ( QgsFieldProxyModel::Filters filters )

setFilters allows fitering according to the type of field

Definition at line 82 of file qgsfieldexpressionwidget.cpp.

◆ setGeomCalculator()

void QgsFieldExpressionWidget::setGeomCalculator ( const QgsDistanceArea & da )

Sets the geometry calculator used in the expression dialog.

Definition at line 113 of file qgsfieldexpressionwidget.cpp.

◆ setLayer

void QgsFieldExpressionWidget::setLayer ( QgsMapLayer * layer )

slot

Sets the layer used to display the fields and expression.

See also: layer()

Definition at line 170 of file qgsfieldexpressionwidget.cpp.

◆ setLeftHandButtonStyle()

void QgsFieldExpressionWidget::setLeftHandButtonStyle ( bool isLeft )

Definition at line 98 of file qgsfieldexpressionwidget.cpp.

◆ setRow

void QgsFieldExpressionWidget::setRow ( int row )

inlineslot

sets the current row in the widget

Definition at line 197 of file qgsfieldexpressionwidget.h.

◆ updateLineEditStyle

void QgsFieldExpressionWidget::updateLineEditStyle ( const QString & expression = QString() )

protectedslot

updateLineEditStyle will re-style (color/font) the line edit depending on content and status

Parameters

expression if expression is given it will be evaluated for the given string, otherwise it takes current expression from the model

Definition at line 339 of file qgsfieldexpressionwidget.cpp.

Friends And Related Function Documentation

◆ TestQgsFieldExpressionWidget

friend class TestQgsFieldExpressionWidget

friend

Definition at line 253 of file qgsfieldexpressionwidget.h.

Property Documentation

◆ allowEmptyFieldName

bool QgsFieldExpressionWidget::allowEmptyFieldName

readwrite

Definition at line 51 of file qgsfieldexpressionwidget.h.

◆ allowEvalErrors

bool QgsFieldExpressionWidget::allowEvalErrors

readwrite

Definition at line 52 of file qgsfieldexpressionwidget.h.

◆ expressionDialogTitle

QString QgsFieldExpressionWidget::expressionDialogTitle

readwrite

Definition at line 49 of file qgsfieldexpressionwidget.h.

◆ filters

QgsFieldProxyModel::Filters QgsFieldExpressionWidget::filters

readwrite

Definition at line 50 of file qgsfieldexpressionwidget.h.

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

/build/qgis-3.10.0+15buster/src/gui/qgsfieldexpressionwidget.h
/build/qgis-3.10.0+15buster/src/gui/qgsfieldexpressionwidget.cpp

Public Slots

Signals

Public Member Functions

Protected Slots

Protected Member Functions

Properties

Friends

Detailed Description

Constructor & Destructor Documentation

◆ QgsFieldExpressionWidget()

Member Function Documentation

◆ allowEmptyFieldName()

◆ allowEvalErrors()

◆ allowEvalErrorsChanged

◆ appendScope()

◆ asExpression()

◆ changeEvent()

◆ currentField()

◆ currentFieldChanged

◆ currentText()

◆ editExpression

◆ eventFilter()

◆ expression()

◆ expressionDialogTitle()

◆ expressionEdited

◆ expressionEditingFinished

◆ fieldChanged [1/2]

◆ fieldChanged [2/2]

◆ filters()

◆ isExpression()

◆ isExpressionValid

◆ isValidExpression()

◆ layer()

◆ registerExpressionContextGenerator()

◆ setAllowEmptyFieldName()

◆ setAllowEvalErrors()

◆ setExpression

◆ setExpressionDialogTitle()

◆ setField

◆ setFilters()

◆ setGeomCalculator()

◆ setLayer

◆ setLeftHandButtonStyle()

◆ setRow

◆ updateLineEditStyle

Friends And Related Function Documentation

◆ TestQgsFieldExpressionWidget

Property Documentation

◆ allowEmptyFieldName

◆ allowEvalErrors

◆ expressionDialogTitle

◆ filters