The null to string transform function is used to convert incoming null values to an empty string. For example:
...is converted to:
Step 1
In your process flow, access settings for your map shape:
Step 2
Select the add transform icon for the required mapping rule - for example:
Step 3
Click the add transform button:
Step 4
Click in the name field to access a list of all available transform functions, then select null to string from the other category:
Step 5
Click the add field button:
Step 7
Click in source fields and select the source field to be used for this transform:
Step 8
Accept your changes (twice).
Step 9
Save the transform. You'll notice that the transform icon is updated to indicate that a transform function is present for the mapping row - for example: