filter expr(submission_time >= ^arg(:min_submission_time)).:min_submission_time argument is optional - i want to be able to use the same action for getting both all as well as the filtered submissions. Is there a way to have a conditional in the action to only apply the :min_submission_time filter if the argument is not nil? As far as I know the action code is evaluated at compile time, so i cant use a normal elixir if/else.