Class: QgsExpressionFieldBuffer

Buffers information about expression fields for a vector layer.

List of all members, including inherited members

Classes

ExpressionField

Methods

addExpression	Add an expression to the buffer
expressions
readXml	Reads expressions from project file
removeExpression	Remove an expression from the buffer
renameExpression	Renames an expression field at a given index
updateExpression	Changes the expression at a given index
updateFields	Adds fields with the expressions buffered in this object to a QgsFields object
writeXml	Saves expressions to xml under the layer node

class qgis.core.QgsExpressionFieldBuffer

Bases: object

class ExpressionField(exp: str | None, fld: QgsField)

class ExpressionField(a0: QgsExpressionFieldBuffer.ExpressionField)

Bases: object

cachedExpression

field

addExpression(self, exp: str | None, fld: QgsField)

Add an expression to the buffer

Parameters:

• exp (Optional[str]) – expression to add

• fld (QgsField) – field to add

expressions(self) → list[QgsExpressionFieldBuffer.ExpressionField]

Return type:

list[QgsExpressionFieldBuffer.ExpressionField]

readXml(self, layer_node: QDomNode)

Reads expressions from project file

Parameters:

layer_node (QDomNode)

removeExpression(self, index: int)

Remove an expression from the buffer

Parameters:

index (int) – index of expression to remove

renameExpression(self, index: int, name: str | None)

Renames an expression field at a given index

Parameters:

• index (int) – The index of the expression to change

• name (Optional[str]) – New name for field

updateExpression(self, index: int, exp: str | None)

Changes the expression at a given index

Parameters:

• index (int) – The index of the expression to change

• exp (Optional[str]) – The new expression to set

updateFields(self, flds: QgsFields)

Adds fields with the expressions buffered in this object to a QgsFields object

Parameters:

flds (QgsFields) – The fields to be updated

writeXml(self, layer_node: QDomNode, document: QDomDocument)

Saves expressions to xml under the layer node

Parameters:

• layer_node (QDomNode)

• document (QDomDocument)