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This document explains how to check for an Empty empty string in the Flow studio using Evaluate Control.

In the below example, we will pass an empty string to the Evaluate control using Custom control. Then we will use the Regex code in the Evaluate control to verify the empty string.

Custom control

1. Use a custom Custom control in the Flow studio flow to build your custom logic.

2. In the Experience Designer, place the below code in the Function node to set an empty string.

   Code Block
   msg.orbita.session.emptyString = ""; return msg;

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You have to use the Evaluate control to check for an empty string in flow the Flow studio.

1. Drop the Evaluate control onto the canvas.

2. Select Custom controlfrom the Input node list. (You will have access to the entire msg object when you use Custom from the list.)

   

3. In the input field, add the empty string property path in which you have the empty string(as a mustache tag).
   In this example, it is at msg.orbita.session.emptyString

   

4. In the pin options, select “matches regex“ from the list and add the below Regex to evaluate.

   Code Block
   ^\s$

   

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