Retort

Retort is a schema migration tool for SQLAlchemy, compares DB schema against table metadata, and updates DB schema according to this.

It depends on the Alembic autogenerate.

Requirements

Retort works with

• Python 3.3+
• SQLAlchemy
• Alembic
• autopep8

Installation

via pip

$ pip install retort

via setup.py

$ python setup.py install

Basic Usage Examples

Generate config file (retort_config.py)

(venv) tpdn@example:~/retort_example$ retort init
Create retort_conf.py.

Edit config file

# retort_config.py
from model import user

TARGETS = [
    {
        'engine': user.engine, #sqlalchemy engine
        'metadata': user.Base.metadata #sqlalchemy metadata
    },
]

# model/user.py
from sqlalchemy import Column, Integer, String, create_engine
from sqlalchemy.ext.declarative import declarative_base


engine = create_engine('mysql+pymysql://foobar:abcdef@localhost/retort_test_db')
Base = declarative_base()


class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String(255))
    fullname = Column(String(255))
    xyz = Column(String(255))

Apply

(venv) tpdn@example:~/retort_example$ retort apply
====================
url: mysql+pymysql://foobar:abcdef@localhost/retort_test_db
logging_name: None
====================
op.create_table('users',
                sa.Column('id', sa.Integer(), nullable=False),
                sa.Column('name', sa.String(length=255), nullable=True),
                sa.Column('fullname', sa.String(length=255), nullable=True),
                sa.Column('xyz', sa.String(length=255), nullable=True),
                sa.PrimaryKeyConstraint('id')
                )

Do you really want to apply this? [y/n]: y

Applying migration......
====================
url: mysql+pymysql://foobar:abcdef@localhost/retort_test_db
logging_name: None
====================
op.create_table('users',
                sa.Column('id', sa.Integer(), nullable=False),
                sa.Column('name', sa.String(length=255), nullable=True),
                sa.Column('fullname', sa.String(length=255), nullable=True),
                sa.Column('xyz', sa.String(length=255), nullable=True),
                sa.PrimaryKeyConstraint('id')
                )

---> Processing time: 0.0894(sec)
Complete!

Update model(remove xyz column)

# model/user.py
from sqlalchemy import Column, Integer, String, create_engine
from sqlalchemy.ext.declarative import declarative_base


engine = create_engine('mysql+pymysql://foobar:abcdef@localhost/retort_test_db')
Base = declarative_base()


class User(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String(255))
    fullname = Column(String(255))
    # xyz = Column(String(255))

Apply with --sql option

(venv) tpdn@example:~/retort_example$ retort apply --sql
====================
url: mysql+pymysql://foobar:abcdef@localhost/retort_test_db
logging_name: None
====================
ALTER TABLE users DROP COLUMN xyz;

Do you really want to apply this? [y/n]: y

Applying migration......
====================
url: mysql+pymysql://foobar:abcdef@localhost/retort_test_db
logging_name: None
====================
ALTER TABLE users DROP COLUMN xyz;

---> Processing time: 0.0745(sec)
Complete!

Commands and Options

retort init

retort apply
  --sql # print sql mode
  --dry-run # dry run (no database update)
  --yes # skip confirmation
  --without-drop # without drop operations (DROP TABLE, DROP COLUMN, DROP INDEX, DROP CONSTRAINT)

retort print_operations
  --sql
  --without-drop

Author

NAKAMORI Ryosuke - https://github.com/tpdn

Licence

BSD License (2-Clause)