Subgroup: Expression
Class: QgsExpressionFieldBuffer¶
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class
qgis.core.
QgsExpressionFieldBuffer
¶ Bases:
sip.wrapper
Constructor for QgsExpressionFieldBuffer.
QgsExpressionFieldBuffer(QgsExpressionFieldBuffer)
Buffers information about expression fields for a vector layer.
New in version 2.6: 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 Signals
Attributes
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class
ExpressionField
(exp: str, fld: QgsField)¶ Bases:
sip.wrapper
QgsExpressionFieldBuffer.ExpressionField(QgsExpressionFieldBuffer.ExpressionField)
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cachedExpression
¶
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field
¶
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addExpression
(self, exp: str, fld: QgsField)¶ Add an expression to the buffer
Parameters: - exp – expression to add
- fld – field to add
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expressions
(self) → object¶
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readXml
(self, layer_node: QDomNode)¶ Reads expressions from project file
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removeExpression
(self, index: int)¶ Remove an expression from the buffer
Parameters: index – 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 – The index of the expression to change
- name – New name for field
New in version 3.0.
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updateExpression
(self, index: int, exp: str)¶ Changes the expression at a given index
Parameters: - index – The index of the expression to change
- exp – The new expression to set
New in version 2.9.
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updateFields
(self, flds: QgsFields)¶ Adds fields with the expressions buffered in this object to a QgsFields object
Parameters: flds – The fields to be updated
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writeXml
(self, layer_node: QDomNode, document: QDomDocument)¶ Saves expressions to xml under the layer node
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class