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https://github.com/kvesteri/sqlalchemy-continuum

Versioning extension for SQLAlchemy.
https://github.com/kvesteri/sqlalchemy-continuum

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Versioning extension for SQLAlchemy.

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SQLAlchemy-Continuum
====================

|Build Status| |Version Status| |Downloads|

Versioning and auditing extension for SQLAlchemy.

Features
--------

- Creates versions for inserts, deletes and updates
- Does not store updates which don't change anything
- Supports alembic migrations
- Can revert objects data as well as all object relations at given transaction even if the object was deleted
- Transactions can be queried afterwards using SQLAlchemy query syntax
- Query for changed records at given transaction
- Temporal relationship reflection. Version object's relationship show the parent objects relationships as they where in that point in time.
- Supports native versioning for PostgreSQL database (trigger based versioning)

QuickStart
----------

::

pip install SQLAlchemy-Continuum

In order to make your models versioned you need two things:

1. Call make_versioned() before your models are defined.
2. Add __versioned__ to all models you wish to add versioning to

.. code-block:: python

from sqlalchemy_continuum import make_versioned

make_versioned(user_cls=None)

class Article(Base):
__versioned__ = {}
__tablename__ = 'article'

id = sa.Column(sa.Integer, primary_key=True, autoincrement=True)
name = sa.Column(sa.Unicode(255))
content = sa.Column(sa.UnicodeText)

article = Article(name='Some article', content='Some content')
session.add(article)
session.commit()

# article has now one version stored in database
article.versions[0].name
# 'Some article'

article.name = 'Updated name'
session.commit()

article.versions[1].name
# 'Updated name'

# lets revert back to first version
article.versions[0].revert()

article.name
# 'Some article'

For completeness, below is a working example.

.. code-block:: python

from sqlalchemy_continuum import make_versioned
from sqlalchemy import Column, Integer, Unicode, UnicodeText, create_engine
from sqlalchemy.orm import create_session, configure_mappers, declarative_base

make_versioned(user_cls=None)

Base = declarative_base()
class Article(Base):
__versioned__ = {}
__tablename__ = 'article'
id = Column(Integer, primary_key=True, autoincrement=True)
name = Column(Unicode(255))
content = Column(UnicodeText)

configure_mappers()
engine = create_engine('sqlite://')
Base.metadata.create_all(engine)
session = create_session(bind=engine, autocommit=False)

article = Article(name=u'Some article', content=u'Some content')
session.add(article)
session.commit()
article.versions[0].name
article.name = u'Updated name'
session.commit()
article.versions[1].name
article.versions[0].revert()
article.name

Resources
---------

- `Documentation `_
- `Issue Tracker `_
- `Code `_

.. image:: http://i.imgur.com/UFaRx.gif

.. |Build Status| image:: https://github.com/kvesteri/sqlalchemy-continuum/workflows/Test/badge.svg
:target: https://github.com/kvesteri/sqlalchemy-continuum/actions?query=workflow%3ATest
.. |Version Status| image:: https://img.shields.io/pypi/v/SQLAlchemy-Continuum.png
:target: https://pypi.python.org/pypi/SQLAlchemy-Continuum/
.. |Downloads| image:: https://img.shields.io/pypi/dm/SQLAlchemy-Continuum.png
:target: https://pypi.python.org/pypi/SQLAlchemy-Continuum/

More information
----------------

- http://en.wikipedia.org/wiki/Slowly_changing_dimension
- http://en.wikipedia.org/wiki/Change_data_capture
- http://en.wikipedia.org/wiki/Anchor_Modeling
- http://en.wikipedia.org/wiki/Shadow_table
- https://wiki.postgresql.org/wiki/Audit_trigger
- https://wiki.postgresql.org/wiki/Audit_trigger_91plus
- http://kosalads.blogspot.fi/2014/06/implement-audit-functionality-in.html
- https://github.com/2ndQuadrant/pgaudit