Formula to keep field empty, and if not empty, display today's date

[malcorr]

Hello, 

i have a field in which, if it comes empty from the input file, i want to keep it empty, and if its not empty, i want to display today's date in that same field (Lets call the field "Date")

Any ideas? i think it should be easy, tried using the below in a "Formula" Tool but it says the IF is malformed. 

IF IsNull([Date]) THEN "" ELSE ToString(DateTimeToday())

[rzdodson · Accepted solution]

@malcorr try this in a Formula tool.

If IsEmpty([Date]) then [Date]
else DateTimeToday()
endif

Edit:

The solution above assumes that your Date field is already in a Date format.

[malcorr]

Thank you! this worked, and yes, the field was already in a date format