ormatic 1.1.1

Automatic Creation of ORM Models from Python Dataclasses.

Welcome to ORMatic

ORMatic is a python package that automatically converts python dataclasses to sqlalchemy tables. This is done using the imperative mapping.

When designing the dataclasses there are a couple of rules that need to be followed:

• Fields that are not mapped start with an _ (underscore).
• The only allowed union is the Optional[_T] union. Whenever you want a union of other types, use inheritance instead.
• Iterables are never optional and never nested. If you want an optional iterable, use an empty iterable as default factory instead.
• No multiple inheritance.
• No forward referenced classes.

Features:

• Automatic conversion of dataclasses to sqlalchemy tables.

• Automatic application of relationships.

• Automatic generation of ORM interface.

• ORM interface only affects your code if it is imported.

• Support for inheritance.

• Support for optional fields.

• Support for nested dataclasses.

• Support for many-many relationships.

• Support for self-referencing relationships.

Example

The most common use case is to create an ORM for an existing set of dataclasses. An example for such a set of dataclasses is found in example.py. The automatically generated ORM interface is found in orm_interface.py. Example usage of the ORM interface is found in integration.py.

The following script generates the bindings in orm_interface.py.

import sqlacodegen.generators
from sqlalchemy import create_engine
from sqlalchemy.orm import registry, Session

from example import *
from ormatic.ormatic import ORMatic


def main():
    mapper_registry = registry()

    engine = create_engine('sqlite:///:memory:')

    classes = [Position, Orientation, Pose, Position4D, Positions, EnumContainer, Node]
    ormatic = ORMatic(classes, mapper_registry)
    ormatic.make_all_tables()
    mapper_registry.metadata.create_all(engine)

    generator = sqlacodegen.generators.TablesGenerator(mapper_registry.metadata, engine, [])

    with open('orm_interface.py', 'w') as f:
        ormatic.to_python_file(generator, f)


if __name__ == '__main__':
    main()