Class: register_function¶
- class qgis.core.register_function(function, arg_count, group, usesgeometry=False, referenced_columns=['#!allattributes!#'], handlesnull=False, **kwargs)¶
Register a Python function to be used as a expression function.
Functions should take (values, feature, parent) as args:
- Example:
- def myfunc(values, feature, parent):
pass
They can also shortcut naming feature and parent args by using *args if they are not needed in the function.
- Example:
- def myfunc(values, *args):
pass
Functions should return a value compatible with QVariant
Eval errors can be raised using parent.setEvalErrorString(“Error message”)
- Parameters
function –
arg_count –
group –
usesgeometry –
handlesnull – Needs to be set to True if this function does not always return NULL if any parameter is NULL. Default False.
- Returns