Class: qgsfunction¶
- class qgis.core.qgsfunction(args='auto', group='custom', **kwargs)¶
Decorator function used to define a user expression function.
- Parameters
args – Number of parameters, set to ‘auto’ to accept a variable length of parameters.
group – The expression group to which this expression should be added.
**kwargs – See below
- Keyword Arguments
referenced_columns (
list
) – An array of field names on which this expression works. Can be set to[QgsFeatureRequest.ALL_ATTRIBUTES]
. By default empty.usesgeometry (
bool
) – Defines if this expression requires the geometry. By default False.handlesnull (
bool
) – Defines if this expression has custom handling for NULL values. If False, the result will always be NULL as soon as any parameter is NULL. False by default.
- Example:
@qgsfunction(2, ‘test’): def add(values, feature, parent):
pass
Will create and register a function in
QgsExpression
called ‘add’ in the ‘test’ group that takes two arguments.or not using feature and parent:
- Example:
@qgsfunction(2, ‘test’): def add(values, *args):
pass