Error: 'list' object has no attribute 'segmentAlongLine'

Question

I am trying to trim each polyline in a shapefile down to the first 15 feet of each line. The segmentAlongLine method was suggested to me, but this code is getting the AttributeError: 'list' object has no attribute 'segmentAlongLine'.

SHAPE@ in this case is a polyline object... Why is it calling it a list and why isn't segmentAlongLine working? I have found questions about this error but none of the answers seem to apply to my issue.

with arcpy.da.UpdateCursor(fc,"SHAPE@") as cursor:  
    for row in cursor:   
        row.segmentAlongLine(0,15)

Answer 1

row is a list containing the shape of the feature. Use row[0].segmentAlongLine(0,15).

Answer 2

What if you try:

errors = []
with arcpy.da.UpdateCursor(fc,["SHAPE@", "OID@"]) as cursor:  
    for row in cursor:
        try:
            row[0].segmentAlongLine(0,15)
        except AttributeError:
            errors.append(row)

What is in errors list?

And you are not changing anything with your code. You need to assign row[0] a new value and cursor.updateRow(row)