Subgroup: Expression

Class: QgsExpressionLineEdit

class qgis.gui.QgsExpressionLineEdit(parent: QWidget = None)

Bases: PyQt5.QtWidgets.QWidget

Constructor for QgsExpressionLineEdit.

Parameters:parent – parent widget

The QgsExpressionLineEdit widget includes a line edit for entering expressions together with a button to open the expression creation dialog.

This widget is designed for use in contexts where no layer fields are available for use in an expression. In contexts where the expression is directly associated with a layer and fields can be used, then QgsFieldExpressionWidget is a more appropriate choice as it gives users direct access to select fields from a drop-down list.

QgsExpressionLineEdit also supports a multiline editor mode which is useful where more space is available for the widget, but where QgsExpressionBuilderWidget is too complex or large for use.

New in version 3.0: Methods

actionEvent
changeEvent
childEvent
closeEvent
connectNotify
contextMenuEvent
create
customEvent
destroy
disconnectNotify
dragEnterEvent
dragLeaveEvent
dragMoveEvent
dropEvent
enterEvent
event
expectedOutputFormat Returns the expected format string, which is shown in the expression builder dialog for the widget.
expression Returns the current expression shown in the widget.
expressionDialogTitle Returns the title used for the expression dialog.
focusInEvent
focusNextChild
focusNextPrevChild
focusOutEvent
focusPreviousChild
hideEvent
initPainter
inputMethodEvent
isSignalConnected
isValidExpression Returns true if the current expression is valid.
keyPressEvent
keyReleaseEvent
leaveEvent
metric
mouseDoubleClickEvent
mouseMoveEvent
mousePressEvent
mouseReleaseEvent
moveEvent
nativeEvent
paintEvent
receivers
registerExpressionContextGenerator Register an expression context generator class that will be used to retrieve an expression context for the widget.
resizeEvent
sender
senderSignalIndex
setExpectedOutputFormat Set the expected format string, which is shown in the expression builder dialog for the widget.
setExpression Sets the current expression to show in the widget.
setExpressionDialogTitle Sets the title used in the expression builder dialog
setGeomCalculator Set the geometry calculator used in the expression dialog.
setLayer Sets a layer associated with the widget.
setMultiLine Sets whether the widget should show a multiline text editor.
sharedPainter
showEvent
tabletEvent
timerEvent
updateMicroFocus
wheelEvent

Signals

expressionChanged Emitted when the expression is changed.

Attributes

actionEvent()
changeEvent(self, event: QEvent)
childEvent()
closeEvent()
connectNotify()
contextMenuEvent()
create()
customEvent()
destroy()
disconnectNotify()
dragEnterEvent()
dragLeaveEvent()
dragMoveEvent()
dropEvent()
enterEvent()
event()
expectedOutputFormat(self) → str

Returns the expected format string, which is shown in the expression builder dialog for the widget. This is purely a text format and no expression validation is done against it.

New in version 3.4.

expression(self) → str

Returns the current expression shown in the widget.

See also

setExpression()

expressionChanged

Emitted when the expression is changed.

Parameters:expression – new expression [signal]
expressionDialogTitle(self) → str

Returns the title used for the expression dialog.

focusInEvent()
focusNextChild()
focusNextPrevChild()
focusOutEvent()
focusPreviousChild()
hideEvent()
initPainter()
inputMethodEvent()
isSignalConnected()
isValidExpression(self) → Tuple[bool, str]

Returns true if the current expression is valid.

Parameters:expressionError – will be set to any generated error message if specified
keyPressEvent()
keyReleaseEvent()
leaveEvent()
metric()
mouseDoubleClickEvent()
mouseMoveEvent()
mousePressEvent()
mouseReleaseEvent()
moveEvent()
nativeEvent()
paintEvent()
receivers()
registerExpressionContextGenerator(self, generator: QgsExpressionContextGenerator)

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.
resizeEvent()
sender()
senderSignalIndex()
setExpectedOutputFormat(self, expected: str)

Set the expected format string, which is shown in the expression builder dialog for the widget. This is purely a text format and no expression validation is done against it.

New in version 3.4.

setExpression(self, expression: str)

Sets the current expression to show in the widget.

Parameters:expression – expression string

See also

expression()

setExpressionDialogTitle(self, title: str)

Sets the title used in the expression builder dialog

Parameters:title – dialog title
setGeomCalculator(self, distanceArea: QgsDistanceArea)

Set the geometry calculator used in the expression dialog.

Parameters:distanceArea – calculator
setLayer(self, layer: QgsVectorLayer)

Sets a layer associated with the widget. Required in order to get the fields and values from the layer. This will also automatically register the layer as expression context generator if no generator has been set before or the previous layer has been used as generator.

setMultiLine(self, multiLine: bool)

Sets whether the widget should show a multiline text editor.

Parameters:multiLine – set to true to show multiline editor, or false to show single line editor (the default).
sharedPainter()
showEvent()
tabletEvent()
timerEvent()
updateMicroFocus()
wheelEvent()