Is it possible to use an optional variable (value2) like

@qgsfunction(args='auto', group='Custom')
def my_test(value1, value2=True, feature, parent)

in a custom function? Using QGIS 3.8

...likeenter image description here

1 Answer 1


Not sure of a direct way but there is the handlesnull flag which when set to true would let you input NULL as a parameter value.

@qgsfunction(args='auto', group='Custom', handlesnull=True)
def my_test(value1, value2, feature, parent):

You might want to include some logic in your code to determine what happens when a parameter value is NULL.

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