You can use the extended conditions to evaluate a parameter value. Use the Show condition and then

• Use “Parameter” as your target.
• Use any table column id to get the value of. (Or at least one that’s normally filled in. This can be the PK column itself.)
• Compare against a non-empty regex with “Regex=.+” as your check.

Normally, the shape won’t show until the condition can evaluate and the condition can’t evaluate if the row key is not found. Therefore this should work.