Class: QgsExpressionFieldBuffer¶
-
class
qgis.core.
QgsExpressionFieldBuffer
¶ Bases:
sip.wrapper
Constructor for QgsExpressionFieldBuffer.
QgsExpressionFieldBuffer(
QgsExpressionFieldBuffer
)Buffers information about expression fields for a vector layer.
Methods
Add an expression to the buffer
- rtype
object
Reads expressions from project file
Remove an expression from the buffer
Renames an expression field at a given index
Changes the expression at a given index
Adds fields with the expressions buffered in this object to a
QgsFields
objectSaves expressions to xml under the layer node
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class
ExpressionField
(exp: str, fld: QgsField)¶ Bases:
sip.wrapper
QgsExpressionFieldBuffer.ExpressionField(QgsExpressionFieldBuffer.ExpressionField)
- Parameters
exp (str) –
fld (QgsField) –
-
cachedExpression
¶
-
field
¶
-
addExpression
(self, exp: str, fld: QgsField)¶ Add an expression to the buffer
- Parameters
exp (str) – expression to add
fld (QgsField) – field to add
-
expressions
(self) → object¶ - Return type
object
-
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
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renameExpression
(self, index: int, name: str)¶ Renames an expression field at a given index
- Parameters
index (int) – The index of the expression to change
name (str) – New name for field
New in version 3.0.
-
updateExpression
(self, index: int, exp: str)¶ Changes the expression at a given index
- Parameters
index (int) – The index of the expression to change
exp (str) – The new expression to set
New in version 2.9.
-
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) –