There are times when you want to validate that the value of a property isn’t blank. For example, you could be checking the output value (published data) of an activity to make sure it’s not blank before proceeding. However, in the list of available comparisons, there isn’t a selection for “Is Null” or “Is Blank”.
So how can you check for blank values?
Use the “Matches Pattern” or “Does Not Match pattern” condition and enter the regular expression ^$ which is interpreted as “blank”.
Thanks to Jeffrey Fanjoy for this Quick Tip!
In some cases \S may be a more desirable match pattern. A field or line that appears empty may actually contain whitespace that $^ would fail to match on.
Why not just use "Parameter 1 from Initialize Data equals" and leave the value empty?
It appears that Match Pattern ^$ does not work on Get Object filters. Just link filters. Is this a bug?