I am using QGIS 3.22 and I am making some algorithm in Modeler enter image description here

I am using Vector Layer as layer and Vector Field as field (it is field with real values and nulls). I want to add column with sum of field. So in Field calculator I use following formula


As a result I get NULL field instead of my input field and the following error message is shown:

Eval Error: Cannot use aggregate function in this context.

How to use aggregate functions correctly?

enter image description here

  • Please provide relevant error messages.
    – Erik
    Commented Feb 27, 2023 at 15:51
  • @Erik Eval Error: Cannot use aggregate function in this context Commented Feb 27, 2023 at 17:30

1 Answer 1


This is a bit tricky in QGIS - may be it is an error because it is not logical, which QGIS mostly is - but anyway, you have to change your formula to precalculated value and then make a string representation of your formula like:

'sum(' || @field || ')'

enter image description here

  • Worked like a charm!
    – chjch
    Commented Jul 5, 2023 at 1:38

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