Empty or Null dates in SharePoint 2010

Turns out that my first, “simple” foray into SharePoint Workflows already hit upon a snag.

How do you test for an empty date in SharePoint 2010?

I did some digging and found that the common consensus was to convert the date to a string (using String Builder) and then use string comparison.  Unfortunately, this didn’t work quite as expected.

Attempt 1: Test Date.“as String” begins with “1/1/0001”

Unfortunately, I don’t know enough about SharePoint to understand why this didn’t work.  Through playing around, I found that if I used String Builder to convert an empty date to a string, the resulting string would be “1/1/0001 12:00:00 AM”.  So, logic would seem to indicate that all I had to do was test to see if a string begins with “1/1/0001.”  However, this did not work!  Maybe someone could tell me why.

Here’s what I did:

• Set Variable: Date as String to [%Current Item: Cutoff Date%]
  • Note: In String Builder, I set Return field as to As String
• If Variable: Date as String begins with 1/1/0001
  • Log Date is empty. to the workflow history list

And, of course, the “Date is empty.” message never appeared in the workflow history.

I never did find out why “begins with” wasn’t operating as expected. I even changed the test to “does not begin with” and my logged output to be “Date does not start with 1/1/0001.  Its value is ‘[%Variable: Date as String%]’.”  Not surprisingly at this point, this time I DID get a message and it stated:

Date does not start with 1/1/0001.  Its value is ‘1/1/0001 12:00:00 AM’.

Someone explain THAT one to me.  Nevertheless, I persisted.

Attempt 2: Test Date.“Short Date” equals “1/1/0001”

Obviously, it occurred to me that I could test the value of the entire string.  But while I was at it, I tried using the “Short Date” setting in String Builder.

I was then able to use essentially my original logic, and this time it worked!

• Set Variable: Date as String to [%Current Item: Cutoff Date%]
  • Note: In String Builder, I set Return field as to Short Date
• If Variable: Date as String equals 1/1/0001
  • Log Date is empty. to the workflow history list

This one worked!  There must be something I’m missing in the “begins with” operator.  But for now, I have a solution to my problem.