This document explains how to check for an Empty empty string in the Flow studio using Evaluate Control.
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You have to use the Evaluate control to check for an empty string in flow the Flow studio.
Drop the Evaluate control onto the canvas.
Select Custom from the Input node list. (You will have access to the entire msg object when you use Custom from the list.)
In the input field, add the empty string property path (as a mustache tag).
In this example, it is atmsg.orbita.session.emptyString
In the pin options, select “matches regex“ from the list and add the below Regex to evaluate.
Code Block ^\s$
The regex ^\s$ will match an empty string or a single space.
If you want to match an empty string or multiple spaces, use ^\s*$
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