Best way to check if a field is empty in a DTL

Question

For a non repeating field. How do I write an If that executes only if the field is empty.

i.e. source.{PID:19}

I've tried source.{PID:19} = "" and source.{PID:19} '= "" in the if (With true and false), but neither worked.

Answer 1

I ended up using ..Length(source.{PID:19})>0 which worked. Thought I had tried this before.