I'm having issues setting a row value to 0 when joining a csv to a shapefile. When the shapefile value is not in the csv, the row is getting set to 0 instead of null. This is a huge problem as i'm showing 0 change instead of no data. I tried row.setValue(field, None) and row.setNull(field) and both produce the same result. In the .dbf file of the shapefile, there is no value but in the UI attribute table a 0 is shown. Any advice on how to fix this would be very appreciated. 


    arcpy.AddField_management(shpfile, "TEST", "DOUBLE", field_is_nullable = 'NULLABLE')

    newcols = ["TEST"]

    with open(csvfile, 'rb') as csvfile:
        lib = dict()
        csvfile = csv.reader(csvfile, delimiter = ",")
        csvfile.next() #skip the headers
        for line in csvfile:
            lib[line[csvjoinindex]] = lib.get(line[csvjoinindex],line[csvstartfield:])
    rows = arcpy.UpdateCursor(shpfile)
    for row in rows:
        shpjoinval = str(row.getValue(shapefilejoincol))
        try:
            vals = lib.get(shpjoinval)
            for ind, field in enumerate(newcols):
                row.setValue(str(field),vals[ind])
                rows.updateRow(row)
        except:
            for ind, field in enumerate(newcols):
                 row.setNull(field)
                 rows.updateRow(row)