CalculateField_management no-success

Question

The following script is suppose to do the following, similar to what was done here: Renaming field using ArcPy?.

1. Create a fieldlist.
2. Read thru the fieldlist and create a new field named "OLD_" + field.name.

3. Copy the values in field to new field.

   import arcpy, os
   
   intable = arcpy.GetParameter(0)
   
   fields = arcpy.ListFields(intable)
   
   try:
       for field in fields:
           if field.name == "OBJECTID" or field.name == "Shape" or field.name == "Shape_Length":
               pass
           else:
               field_name = field.aliasName
               old_field = field_name + "OLD_"
               field_precision = field.precision
               field_scale = field.scale
               field_length = field.length
               field_type = field.type
   
               arcpy.AddField_management(intable, old_field, field_type, field_precision, field_scale, field_length)
   
               arcpy.CalculateField_management(intable, old_field, "!"+field+"!")        
   except:
       print arcpy.GetMessages()
   
   del intable, fields, field
   

Two problems:

1. The script stops upon reaching the CalculateField_management code, which is one iteration, but there are approximately 50 more fields in the list that are ignored.
2. The newly create field is empty, the values are not copied across.

I have tried everything and followed the example given in the link above, but nothing has fixed these two problems.

Answer 1

Try changing this line:

intable = arcpy.GetParameter(0)

to

intable = arcpy.GetParameterAsText(0)

Also I think you meant this line:

old_field = field_name + "OLD_"

to actually be

old_field = "OLD_" + field_name 

Finally your calculate line should be:

arcpy.CalculateField_management(intable, old_field, '"' + "!" + field.name + "!" + '"')  

Answer 2

Which version of ArcGIS do you use? Since 10.2 there's the Alter Field tool that allows to rename a field directly. No need to add and calculate a new field and delete the old one. No need to figure out the correct calculate field expression, all field properties are kept and it's super fast even if you have many fields. Works only with geodatabases fc & tables, not shapefiles.

This would be your code:

import arcpy, os
intable = arcpy.GetParameterAsText(0)
fields = arcpy.ListFields(intable)

try:
    for field in fields:
       if not field.required:       # Couldn't help improving this part as well :)
           arcpy.AlterField_management(intable, field.name, field.name + "_OLD")       

except:
    print arcpy.GetMessages()

del intable, fields, field