RetroFix documentation

RetroFix is a python library for reading and writing fixed-size field text file and more specifically for managing files from Spanish banks and public institutions, including:

• CSB 19, 32, 34 (several versions), 43, 57 & 58
• AEAT 303, 340, 347 & 349

Defining record structures

RetroFix allows an easy way to define the structure of fixed size records by creating a tuple which contains a tuple of size 4 for each field, containing: start position, length, name and type.

Start position and length are numeric fields which define where the field is located in a given record. The name is the internal name of the field and type is a class or instance of a class inheriting retrofix.fields.Field.

RetroFix provides the following field types (new ones can also be created):

Char

This is the simplest one and stores the content in a string.

Const

This one inherits Char but ensures that the record contains the exact characters defined as parameter of the constructor.

Account

Inherits Char but checks that the value of the field is a valid bank account number as defined by Spanish bank number format.

Numeric

Used for numeric fields. You can get and set the value using Decimals.

Integer

Just like Numeric but with integers.

Date

Ensures the field matches the date format supplied to the constructor.

Selection

Only allows a given set of string values supplied to the constructor.

Boolean

Similar to selection but only two values are accepted (supplied to the constructor) and you can set and get the values using a boolean.

Take a look at the following example:

from retrofix import record
from retrofix.fields import *

RECORD = (
    (  1,  2, 'record_type', Const('XX')),
    (  3, 10, 'name', Char),
    ( 33, 15, 'amount', Number(sign=SIGN_N)),
    ( 38, 17, 'date', Date('%d%m%y')),
    )

def read(data):
    lines = data.splitlines()
    records = []
    current_line = lines.pop(0)
    records.append(record.Record.extract(current_line, RECORD))
    return records

lines = read(open('myfile.txt', 'r').read())
f = open('newfile.txt')
try:
    f.write(record.write(lines))
finally:
    f.close()