Copies the attributes of a field (data type, precision, scale, length, isNullable, required, domain) to a new field on a new table. Correctly maps data types pulled from Describe tool to data types needed for field creation.

copy_field_attributes_to_new_field.py

def copy_field_attributes_to_new_field(source_table, current_field, target_table, target_field):
	"""
		Copies the attributes of a field (data type, precision, scale, length, isNullable, required, domain) to a new field on a new table.
		Correctly maps data types pulled from Describe tool to data types needed for field creation.
	:param source_table: The table containing the existing field
	:param current_field: The field to copy attributes from
	:param target_table: The field to create the new field on
	:param target_field: The name of the new field to create with the attributes from current_field
	:return:
	"""

	# first, we need to find the information about the field that we're attaching
	join_table_fields = arcpy.ListFields(source_table)
	for field in join_table_fields:
		if field.name == current_field:  # we found our attribute
			base_field = field
			break
	else:
		raise ValueError("Couldn't find field to base join on in source table")

	type_mapping = {"Integer": "LONG", "OID": "LONG", "SmallInteger": "SHORT",
					"String": "TEXT"}  # ArcGIS annoyingly doesn't report out the same data types as you need to provide, so this allows us to map one to the other
	if base_field.type in type_mapping.keys():  # if it's a type that needs conversion
		new_type = type_mapping[base_field.type]  # look it up and save it
	else:
		new_type = base_field.type.upper()  # otherwise, just grab the exact type as specified

	if target_field:
		new_name = target_field
	else:
		new_name = base_field.name

	# copy the field over other than those first two attributes
	arcpy.AddField_management(target_table, new_name, new_type, field.precision, field.scale, field.length,
							  field_alias=None, field_is_nullable=field.isNullable, field_is_required=field.required,
							  field_domain=field.domain)