SQLAlchemy-Mutable

SQLAlchemy-Mutable aspires to be the most powerful and flexible SQLAlchemy database column type.

Its features include:

  1. Nested mutation tracking
  2. Mutation tracking for list and dict
  3. Support for storing database models in mutable columns
  4. Support for common literals and datetime objects
  5. Support for custom mutable classes
  6. Support for converting existing classes to mutable classes
  7. Compatibility with Flask-SQLAlchemy

Installation

$ pip install sqlalchemy-mutable

Quickstart

Setup:

from sqlalchemy_mutable import Mutable, MutableType, MutableModelBase, Query

from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.orm import sessionmaker, scoped_session
from sqlalchemy.ext.declarative import declarative_base

# create a session (standard)
engine = create_engine('sqlite:///:memory:')
session_factory = sessionmaker(bind=engine)
Session = scoped_session(session_factory)
session = Session()
Base = declarative_base()

# subclass `MutableModelBase` when creating database models 
# which may be stored in a `Mutable` object
class MyModel(MutableModelBase, Base):
    __tablename__ = 'mymodel'
    id = Column(Integer, primary_key=True)
    greeting = Column(String)

    # initialize a database column with `MutableType`
    mutable = Column(MutableType) 
    # add a `query` class attribute initialized with a scoped_session
    # not necessary for use with Flask-SQLAlchemy
    query = Query(Session) 

    def __init__(self):
        # set mutable column to `Mutable` object
        self.mutable = Mutable()

# create the database (standard)
Base.metadata.create_all(engine)

Examples:

model = MyModel()
session.add(model)
session.commit()

# nested mutable objects
model.mutable.nested_mutable = Mutable()
session.commit()
model.mutable.nested_mutable.greet = 'hello world'
session.commit()
print(model.mutable.nested_mutable.greet)

# nested mutable list and dict
model.mutable = {}
session.commit()
model.mutable['greet'] = ['hello world']
session.commit()
print(model.mutable)

# storing database models
model.mutable = model
session.commit()
print(model.mutable)

# common literals
model.mutable = 'hello world'
session.commit()
print(model.mutable)

Out:

hello world
{'greet': ['hello world']}
<__main__.MyModel object at 0x7fe54a2d7b00>
hello world

Citation

@software{bowen2020sqlalchemy-mutable,
  author = {Dillon Bowen},
  title = {SQLAlchemy-Mutable},
  url = {https://dsbowen.github.io/sqlalchemy-mutable/},
  date = {2020-10-16},
}

License

Users must cite this package in any publications which use it.

It is licensed with the MIT License.

Acknowledgments

Original inspiration drawn from SQLAlchemy-JSON.