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https://github.com/corridor/sqlalchemy-history

Library to keep track of changes in SQLAlchemy.
https://github.com/corridor/sqlalchemy-history

database hactoberfest mssql mysql oracle postgresql sqlalchemy sqlite

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Library to keep track of changes in SQLAlchemy.

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# SQLAlchemy-History



SQLAlchemy-history is a fork of sqlalchemy-continuum.

An auditing extension for sqlalchemy which keeps a track of the history of your sqlalchemy models



## Features



- Supports sqlalchemy 2+ and python 3.7+

- Tracks history 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. Get the relationships of an object in that point in time.



## QuickStart



```sh

pip install sqlalchemy-history

```



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



```python

>>> from sqlalchemy_history 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'

>>> article.versions[0].revert()

'lets revert back to first version'

>>> article.name

'Some article'

```



For completeness, below is a working example.



```python

from sqlalchemy_history import make_versioned

from sqlalchemy import Column, Integer, Unicode, UnicodeText, create_engine

from sqlalchemy.orm import declarative_base

from sqlalchemy.orm import create_session, configure_mappers

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='Some article', content='Some content')

session.add(article)

session.commit()

print(article.versions[0].name) # 'Some article'

article.name = 'Updated name'

session.commit()

print(article.versions[1].name) # 'Updated name'

article.versions[0].revert()

print(article.name) # 'Some article'

```



## Resources



- [Documentation](https://corridor.github.io/sqlalchemy-history/)

- [Issue Tracker](http://github.com/corridor/sqlalchemy-history/issues)

- [Code](http://github.com/corridor/sqlalchemy-history/)



## More information



- [http://en.wikipedia.org/wiki/Slowly_changing_dimension](http://en.wikipedia.org/wiki/Slowly_changing_dimension)

- [http://en.wikipedia.org/wiki/Change_data_capture](http://en.wikipedia.org/wiki/Change_data_capture)

- [http://en.wikipedia.org/wiki/Anchor_Modeling](http://en.wikipedia.org/wiki/Anchor_Modeling)

- [http://en.wikipedia.org/wiki/Shadow_table](http://en.wikipedia.org/wiki/Shadow_table)

- [https://wiki.postgresql.org/wiki/Audit_trigger](https://wiki.postgresql.org/wiki/Audit_trigger)

- [https://wiki.postgresql.org/wiki/Audit_trigger_91plus](https://wiki.postgresql.org/wiki/Audit_trigger_91plus)

- [http://kosalads.blogspot.fi/2014/06/implement-audit-functionality-in.html](http://kosalads.blogspot.fi/2014/06/implement-audit-functionality-in.html)

- [https://github.com/2ndQuadrant/pgaudit](https://github.com/2ndQuadrant/pgaudit)



## Comparison



Primary reasons to create another library:



- Be future looking and support sqlalchemy 2.x

- Support multiple databases (sqlite, mysql, postgres, mssql, oracle)

- Focus on the history tracking and be as efficient as possible when doing it



We found multiple libraries which has an implementation of history tracking:



1. [sqlalchemy-continuum](https://github.com/kvesteri/sqlalchemy-continuum)

    - Does not support oracle, mssql

    - Feature filled making it difficult to maintain all plugins/extensions

2. [flask-continuum](https://github.com/bprinty/flask-continuum)

    - Thin wrapper on sqlalchemy-continuum specifically for flask

3. [postgresql-audit](https://github.com/kvesteri/postgresql-audit)

    - Supports only postgres

4. [versionalchemy](https://github.com/NerdWalletOSS/versionalchemy)

    - Not updated in a while

    - No reverting capability, Relationship queries on history not available

5. [django-simple-history](https://github.com/jazzband/django-simple-history)

    - Uses django ORM, does not support sqlalchemy

6. [sqlalchemy example versioning-objects](http://docs.sqlalchemy.org/en/latest/orm/examples.html#versioning-objects)

    - Simple example to demonstrate implementation - but very minimal