How to use substring without knowing string length

[MattMcQ]

I have a flow that reads a SharePoint list and converts that into a CSV table with custom columns. I was trying to take one of the columns and use the substring() function on it to only take the first 90 characters like this: 

Substring(@item()?['Justification_x0020_for_x0020_Sp'],0,90)

. However this throws an error when the field is empty or less than 90 characters long. I was going to try and manage this AFTER the CSV table was created but the field is rich text and can contain line feeds so I can't do a split for each row and then  try to process each column. 

Is there a way to just pull the first X characters of a field in the CSV table step without the substring() function?

[Paulie78 · Accepted solution]

You could do this:

if
(
  greater(length(outputs('Justification')), 90),
  substring(outputs('Justification'), 0, 90),
  outputs('Justification')
)

You will need to replace outputs('Justification') with your value. 

This checks to see if the string is greater than 90 characters, if it is, it gets the first 90 characters. If it is less than 90, it just outputs the value.

Make sense?

[MattMcQ]

I thought I tried that and it didn't work, but I wasn't using greater(). It does work now though. Thank you.