Class: QgsExpressionSelectionDialog

A dialog for selecting features by expression.

To do so, a QgsExpressionBuilderWidget is shown in a dialog. It offers the possibilities to create a new selection, add to the current selection remove from the current selection or select within the current selection.

Class Hierarchy

Base classes

QDialog
QWidget
QObject
QPaintDevice

class qgis.gui.QgsExpressionSelectionDialog

Bases: QDialog

__init__(layer: QgsVectorLayer | None, startText: str | None = '', parent: QWidget | None = None)

Creates a new selection dialog.

Parameters:

• layer (Optional[QgsVectorLayer]) – The layer on which the selection is to be performed.

• startText (Optional[str] = '') – A default expression text to be applied (Defaults to empty)

• parent (Optional[QWidget] = None) – parent object (owner)

virtual closeEvent(self, closeEvent: QCloseEvent | None)

Implementation for closeEvent Saves the window geometry

Parameters:

closeEvent (Optional[QCloseEvent]) – Event object. Unused.

virtual done(self, r: int)

Implementation for done (default behavior when pressing esc) Calls close, so the window geometry gets saved and the object deleted.

Parameters:

r (int) – Result value. Unused.

expressionBuilder(self) → QgsExpressionBuilderWidget | None

The builder widget that is used by the dialog

Return type:

Optional[QgsExpressionBuilderWidget]

Returns:

The builder widget that is used by the dialog

expressionText(self) → str

Returns the current expression text

Return type:

str

Returns:

The expression text

setExpressionText(self, text: str | None)

Sets the current expression text

Parameters:

text (Optional[str]) – the expression text to set

setGeomCalculator(self, da: QgsDistanceArea)

Sets geometry calculator used in distance/area calculations.

Parameters:

da (QgsDistanceArea)

setMapCanvas(self, canvas: QgsMapCanvas | None)

Sets a map canvas associated with the dialog.

Parameters:

canvas (Optional[QgsMapCanvas])

setMessageBar(self, messageBar: QgsMessageBar | None)

Sets the message bar to display feedback from the dialog. This is used when zooming to features to display the count of selected features.

Parameters:

messageBar (Optional[QgsMessageBar]) – target message bar