schwifty by example

Basics

IBAN-objects are usually created from their string representation

>>> from schwifty import IBAN
>>> iban = IBAN('DE89 3704 0044 0532 0130 00')
<IBAN=DE89370400440532013000>

Afterwards you can access all relevant components and meta-information of the IBAN as attributes.

>>> str(iban)
'DE89370400440532013000'
>>> iban.formatted
'DE89 3704 0044 0532 0130 00'
>>> iban.country_code
'DE'
>>> iban.bank_code
'37040044'
>>> iban.account_code
'0532013000'
>>> len(iban)
22

For some countries it is also possible to get ahold of the BIC associated to the bank-code of the IBAN.

>>> iban.bic
<BIC=COBADEFFXXX>

A BIC is a unique identification code for both financial and non-financial institutes. schwifty provides a BIC-object, that has a similar interface to the IBAN.

>>> from schwifty import BIC
>>> bic = BIC('PBNKDEFFXXX')
>>> bic.bank_code
'PBNK'
>>> bic.branch_code
'XXX'
>>> bic.country_code
'DE'
>>> bic.location_code
'FF'
>>> bic.domestic_bank_codes
['10010010',
 '20010020',
 ...
 '86010090']

The BIC.domestic_bank_codes lists the country specific bank codes as you can find them as part of the IBAN. This mapping is included in a manually curated registry that ships with schwifty. and currently includes entries for the following countries:

  • Austria

  • Belgium

  • Bulgaria

  • Croatia

  • Czech Republic

  • Finland

  • France

  • Germany

  • Great Britan

  • Hungary

  • Ireland

  • Latvia

  • Lithuania

  • Netherlands

  • Poland

  • Romania

  • Saudi Arabia

  • Slovakia

  • Slovenia

  • Spain

  • Sweden

  • Switzerland

Note

The IBAN and BIC classes are subclasses of str so that all methods and functionallities (e.g. slicing) can be directly used. E.g.

>>> iban = IBAN('DE89 3704 0044 0532 0130 00')
>>> iban[2:4]
"89"
>>> iban.count("0")
8
>>> iban.startswith("DE")
True

Validation

When it comes to validation the IBAN and BIC constructors raise an exception whenever the provided code is incorrect for some reason. schwifty comes with a number of dedicated exceptions classes that help identify the concrete reason for the validation error. They all derive from a common base exception SchwiftyException which makes it easy to catch all validation failures if the concrete cause is not important to you.

Note

Prior to schwifty 2021.01.0 a ValueError was raised for all kind of validation failures. In order to keep backwards compatiblity schwifty’s base exception is a subclass of ValueError.

For IBANs - with respect to ISO 13616 compliance - it is checked if the account-code, the bank-code and possibly the branch-code have the correct country-specific format. E.g.:

>>> IBAN('DX89 3704 0044 0532 0130 00')
...
InvalidCountryCode: Unknown country-code DX

>>> IBAN('DE99 3704 0044 0532 0130 00')
...
InvalidChecksumDigits: Invalid checksum digits

Since version 2021.05.1 schwifty also provides the ability to validate the country specific checksum within the BBAN. This currently works for German and Italian banks. For German IBANs the bank specific checksum algorithm for the account code is derived from the bank code. This functionality is currently opt-in and can be used by providing the validate_bban paramter to the IBAN constructor or the IBAN.validate()-method.

>>> iban = IBAN('DE20 2909 0900 8840 0170 00')
>>> iban.validate(validate_bban=True)
...
InvalidBBANChecksum: Invalid BBAN checksum

>>> IBAN('DE20 2909 0900 8840 0170 00', validate_bban=True)
...
InvalidBBANChecksum: Invalid BBAN checksum

For BICs it is checked if the country-code and the length is valid and if the structure matches the ISO 9362 specification.

>>> BIC('PBNKDXFFXXX')
...
InvalidCountryCode: Invalid country code DX

>>> BIC('PBNKDXFFXXXX')
...
InvalidLength: Invalid length 12

>>> BIC('PBNKD1FFXXXX')
...
InvalidStructure: Invalid structure PBN1DXFFXXXX

Note

Starting from schwifty 2023.11.0 BIC values are being validated in the context of ISO 9362:2022 which allows numbers to be part of the business prefix (the first 4 characters of the BIC). The SWIFT however still enforces alphabetic characters only. If strict SWIFT compliance is required you can use the enforce_swift_compliance-parameter, e.g.

>>> BIC("1234DEWWXXX", enforce_swift_compliance=True)
...
InvalidStructure: Invalid structure 1234DEWWXXX

If catching an exception would complicate your code flow you can also use the IBAN.is_valid property. E.g.:

if IBAN(value, allow_invalid=True).is_valid:
  # do something with value

Generation

You can generate IBAN-objects from country-code, bank-code and account-number by using the IBAN.generate()-method. It will automatically calculate the correct checksum digits for you.

>>> iban = IBAN.generate('DE', bank_code='10010010', account_code='12345')
<IBAN=DE40100100100000012345>
>>> iban.checksum_digits
'40'

Notice that even that the account-code has less digits than required (in Germany accounts should be 10 digits long), zeros have been added at the correct location.

For some countries you can also generate BIC-objects from local bank-codes, e.g.:

>>> bic = BIC.from_bank_code('DE', '43060967')
>>> bic.formatted
'GENO DE M1 GLS'

In case there are multiple BICs that can be related to a domestic bank code you can also use the BIC.candidates_from_bank_code()-method to get a list of all knwon BIC candidates.

>>> BIC.candidates_from_bank_code('FR', '30004') 
[<BIC=BNPAFRPPIFN>, <BIC=BNPAFRPPPAA>, <BIC=BNPAFRPPMED>, <BIC=BNPAFRPPCRN>,
 <BIC=BNPAFRPP>, <BIC=BNPAFRPPPAE>, <BIC=BNPAFRPPPBQ>, <BIC=BNPAFRPPNFE>,
 <BIC=BNPAFRPPPGN>, <BIC=BNPAFRPPXXX>, <BIC=BNPAFRPPBOR>, <BIC=BNPAFRPPCRM>,
 <BIC=BNPAFRPPPVD>, <BIC=BNPAFRPPPTX>, <BIC=BNPAFRPPPAC>, <BIC=BNPAFRPPPLZ>,
 <BIC=BNPAFRPP039>, <BIC=BNPAFRPPENG>, <BIC=BNPAFRPPNEU>, <BIC=BNPAFRPPORE>,
 <BIC=BNPAFRPPPEE>, <BIC=BNPAFRPPPXV>, <BIC=BNPAFRPPIFO>]

Pydantic integration

The IBAN and BIC types can be directly used for the popular data validation library Pydantic like so

from pydantic import BaseModel
from schwifty import IBAN


class Model(BaseModel):
  iban: IBAN

model = Model(iban="DE89370400440532013000")  # OK
model = Model(iban="DX89370400440532013000")  # Raises ValidationError due to invalid country code