QGIS API Documentation  2.99.0-Master (6a61179)
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QgsFieldExpressionWidget Class Reference

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:
Inheritance graph
[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 fieldChanged (const QString &fieldName)
 the signal is 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...
 
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
 Return 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 ()
 return 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
 Return true if the current expression is valid. More...
 
QgsVectorLayerlayer () 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 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)
 set 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
 

Properties

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 42 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 28 of file qgsfieldexpressionwidget.cpp.

Member Function Documentation

§ 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).

Note
added in QGIS 2.14

Definition at line 108 of file qgsfieldexpressionwidget.cpp.

§ changeEvent()

void QgsFieldExpressionWidget::changeEvent ( QEvent *  event)
overrideprotected

Definition at line 243 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
isExpressiondetermines if the string returned is the name of a field or an expression
isValiddetermines if the expression (or field) returned is valid

Definition at line 129 of file qgsfieldexpressionwidget.cpp.

§ currentFieldChanged

void QgsFieldExpressionWidget::currentFieldChanged ( )
protectedslot

Definition at line 268 of file qgsfieldexpressionwidget.cpp.

§ currentText()

QString QgsFieldExpressionWidget::currentText ( ) const

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

Definition at line 103 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 206 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()

Note
added in QGIS 3.0

Definition at line 113 of file qgsfieldexpressionwidget.cpp.

§ expressionDialogTitle()

const QString QgsFieldExpressionWidget::expressionDialogTitle ( )
inline

return the title used for the expression dialog

Definition at line 60 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 227 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 233 of file qgsfieldexpressionwidget.cpp.

§ fieldChanged [1/2]

void QgsFieldExpressionWidget::fieldChanged ( const QString &  fieldName)
signal

the signal is 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 68 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 124 of file qgsfieldexpressionwidget.cpp.

§ isExpressionValid

bool QgsFieldExpressionWidget::isExpressionValid ( const QString &  expressionStr)
protectedslot

Definition at line 325 of file qgsfieldexpressionwidget.cpp.

§ isValidExpression()

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

Return true if the current expression is valid.

Definition at line 118 of file qgsfieldexpressionwidget.cpp.

§ layer()

QgsVectorLayer * QgsFieldExpressionWidget::layer ( ) const

Returns the layer currently associated with the widget.

See also
setLayer()

Definition at line 145 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
generatorA QgsExpressionContextGenerator class that will be used to create an expression context when required.
Note
added in QGIS 3.0

Definition at line 150 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.

Note
Added in QGIS 3.0

Definition at line 201 of file qgsfieldexpressionwidget.cpp.

§ setExpressionDialogTitle()

void QgsFieldExpressionWidget::setExpressionDialogTitle ( const QString &  title)

define the title used in the expression dialog

Definition at line 73 of file qgsfieldexpressionwidget.cpp.

§ setField

void QgsFieldExpressionWidget::setField ( const QString &  fieldName)
slot

sets the current field or expression in the widget

Definition at line 173 of file qgsfieldexpressionwidget.cpp.

§ setFilters()

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

setFilters allows fitering according to the type of field

Definition at line 78 of file qgsfieldexpressionwidget.cpp.

§ setGeomCalculator()

void QgsFieldExpressionWidget::setGeomCalculator ( const QgsDistanceArea da)

set the geometry calculator used in the expression dialog

Definition at line 98 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 155 of file qgsfieldexpressionwidget.cpp.

§ setLeftHandButtonStyle()

void QgsFieldExpressionWidget::setLeftHandButtonStyle ( bool  isLeft)

Definition at line 83 of file qgsfieldexpressionwidget.cpp.

§ setRow

void QgsFieldExpressionWidget::setRow ( int  row)
inlineslot

sets the current row in the widget

Definition at line 147 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
expressionif expression is given it will be evaluated for the given string, otherwise it takes current expression from the model

Definition at line 290 of file qgsfieldexpressionwidget.cpp.

Friends And Related Function Documentation

§ TestQgsFieldExpressionWidget

friend class TestQgsFieldExpressionWidget
friend

Definition at line 200 of file qgsfieldexpressionwidget.h.

Property Documentation

§ expressionDialogTitle

QString QgsFieldExpressionWidget::expressionDialogTitle
readwrite

Definition at line 45 of file qgsfieldexpressionwidget.h.

§ filters

QgsFieldProxyModel::Filters QgsFieldExpressionWidget::filters
readwrite

Definition at line 47 of file qgsfieldexpressionwidget.h.


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