Class: QgsExpressionBuilderDialog

A generic dialog for building expression strings.

Class Hierarchy

Base classes

QDialog
QWidget
QObject
QPaintDevice

Methods

allowEvalErrors	Allow accepting invalid expressions.
expectedOutputFormat	Returns the expected format string, which is shown in the dialog.
expressionBuilder	The builder widget that is used by the dialog
expressionContext	Returns the expression context for the dialog.
expressionText
setAllowEvalErrors	Allow accepting expressions with evaluation errors.
setExpectedOutputFormat	Set the expected format string, which is shown in the dialog.
setExpressionContext	Sets the expression context for the dialog.
setExpressionText
setGeomCalculator	Sets geometry calculator used in distance/area calculations.

Virtual Methods

In PyQGIS, only methods marked as virtual can be safely overridden in a Python subclass of QgsExpressionBuilderDialog. See the FAQ for more details.

done	Is called when the dialog get accepted or rejected Used to save geometry

Signals

allowEvalErrorsChanged

Allow accepting expressions with evaluation errors.

class qgis.gui.QgsExpressionBuilderDialog

Bases: QDialog

allowEvalErrors(self) → bool

Allow accepting invalid expressions. This can be useful when we are not able to provide an expression context of which we are sure it’s completely populated.

Return type:

bool

signal allowEvalErrorsChanged

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.

virtual done(self, r: int)

Is called when the dialog get accepted or rejected Used to save geometry

Parameters:

r (int) – result value (unused)

expectedOutputFormat(self) → str

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

See also

setExpectedOutputFormat()

Return type:

str

expressionBuilder(self) → QgsExpressionBuilderWidget | None

The builder widget that is used by the dialog

Return type:

Optional[QgsExpressionBuilderWidget]

expressionContext(self) → QgsExpressionContext

Returns the expression context for the dialog. The context is used for the expression preview result and for populating the list of available functions and variables.

See also

setExpressionContext()

Return type:

QgsExpressionContext

expressionText(self) → str

Return type:

str

setAllowEvalErrors(self, allowEvalErrors: bool)

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.

Parameters:

allowEvalErrors (bool)

setExpectedOutputFormat(self, expected: str | None)

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

See also

expectedOutputFormat()

Parameters:

expected (Optional[str])

setExpressionContext(self, context: QgsExpressionContext)

Sets the expression context for the dialog. The context is used for the expression preview result and for populating the list of available functions and variables.

Parameters:

context (QgsExpressionContext) – expression context

See also

expressionContext()

setExpressionText(self, text: str | None)

Parameters:

text (Optional[str])

setGeomCalculator(self, da: QgsDistanceArea)

Sets geometry calculator used in distance/area calculations.

Parameters:

da (QgsDistanceArea)