QGIS Calculate Field with Function Editor invalid expression

Question

I have some data which is built like this:

a,bbb,ccc

where bbb and ccc vary in length.

I want to extract the last segment of the string, after the second ",". Using the Function Editor:

from qgis.core import *
from qgis.gui import *

@qgsfunction(args='auto', group='Custom')
def sp_split(value1):
    return value1.split(",")[2]

I save it as a function called sp_split, but when I call it in the expression with a field for a value, it doesn't recognize it.

Pressing More Info gives me this explanation:

Eval Error:
sp_split() takes exactly 1 argument (3 given)

What might be the reason for that? I'm at a loss here. I'm using the function because of the split, if there is another way of using the built-in expression to retain the "ccc" part, I'll gladly use it.

Answer 1

I think you need to add from qgis.utils import qgsfunction into your code. You can also remove the other imports as they're not necessary. So something like this should work:

from qgis.utils import qgsfunction

@qgsfunction(args="auto", group='Custom')
def sp_split(value1, feature, parent):
    return value1.split(",")[2]