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BAI2 Parser

Project description

Python module for parsing and writing BAI2 files.

The library is not production ready at the moment as we don’t have enough data to test against, please help us improve it.


Only Python 3.6+ is supported.


pip install bai2


To use bai2 in a project

>>> from bai2 import bai2

>>> # parse from a file
>>> with open(<file-path>) as f:
>>>     bai2_file = bai2.parse_from_file(f)

>>> # parse from a string
>>> bai2_file = bai2.parse_from_string(<bai2_as_string>)

>>> # parse from lines
>>> bai2_file = bai2.parse_from_lines(<bai2_as_lines>)

The parse_from_* methods return a bai2.models.Bai2File object which can be used to inspect the parsed data.

To write a BAI2 file:

>>> from bai2 import bai2
>>> from bai2 import models

>>> bai2_file = models.Bai2File()
>>> bai2_file.header.sender_id = 'EGBANK'

>>> bai2_file.children.append(models.Group())

>>> transactions = [models.TransactionDetail(amount=100)]
>>> bai2_file.children[0].children.append(models.Account(children=transactions))

>>> # write to string
>>> output = bai2.write(bai2_file)


Models structure:


Section models define a header, a trailer and a list of children whilst single models define properties matching the bai2 fields.

Each Model has a rows property with the original rows from the BAI2 file.


The parse method might raise 3 exceptions:

  1. ParsingException: when the file contains an error and the library can’t interpret the data
  2. NotSupportedYetException: when the library doesn’t support the feature yet
  3. IntegrityException: when the control totals or the number of objects reported in the trailers don’t match the ones in the file.


We’ve noticed that different banks implement the specs in slightly different ways and the parse method might therefore raise an ParsingException. It is expected to work correctly with files produced by NatWest, RBS, and JP Morgan.

We don’t know yet how to deal with these cases as we don’t have access to many bai2 files so we can’t test it as we would like.

Please let me know if this happens to you.


Please report bugs and open pull requests on GitHub.

Use python test or tox to run all tests.

Distribute a new version to PyPi by updating the VERSION tuple in bai2/ and publishing a release in GitHub (this triggers a GitHub Actions workflow to automatically upload it). Alternatively, run python sdist bdist_wheel upload locally. Remember to update History.


0.8.2 (2022-01-26)
No library changes Add testing for python 3.9 and 3.10
0.8.0 (2020-11-11)
Remove support for python versions below 3.6
0.7.0 (2019-10-03)
rows no longer required in BAI2 models (c.f. issue 12 and PR 13)
0.6.0 (2019-09-18)
Fix regular expression escaping Add python 3.7 testing
0.5.0 (2018-03-05)
Updated packaging details and improved python version compatibility
0.1.0 (2015-08-06)
Original release

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