Python-code "max value among fields and print field name" working in ArcGIS Pro command line, not in script-tool

Question

I tried this code in ArcGIS Pro.

I am getting the code to work great in command line. However, trying to script a tool out it in ArcGIS Pro.

Getting an error:

File "", line 13, in AttributeError: 'str' object has no attribute 'extend'.

Here is the code:

import arcpy
#input data and fields to find maximum
table = arcpy.GetParameterAsText(0)
fields = arcpy.GetParameterAsText(1)
n = len(fields)
# Add fields to input table to store maximum and field name
maxfield = arcpy.GetParameterAsText(2)
maxname = arcpy.GetParameterAsText(3)
arcpy.AddField_management(table, maxfield, "DOUBLE")
arcpy.AddField_management(table, maxname, "TEXT"
fields2 = fields[:] # shallow copy
fields2.extend([maxfield, maxname])
with arcpy.da.UpdateCursor(table, fields2) as cursor:
 for row in cursor:
 # Look at the first n values
 check = row[:n]
 maxval = max(check)
 # Get the index position of the maxval and use it slice into field list
 # which gives us the field name
 # only update the last two rows
 row[-2:] = maxval, fields[check.index(maxval)]
 cursor.updateRow(row)

Answer 1

You are using GetParamterAsText, so the input fields variable is a string. If you print the fields variable using arcpy.AddMessage you will see how the GetParameterAsText handles the multiple field inputs as text. Convert the input string to a list.

fields = arcpy.GetParameterAsText(1).replace("'", "").split(";")