half-orm 0.18.12

A simple PostgreSQL to Python mapper.

halfORM

⚠️ BREAKING CHANGE in v0.18 — psycopg2 → psycopg 3

halfORM 0.18 drops psycopg2 and requires psycopg 3.

pip uninstall psycopg2-binary
pip install "psycopg[binary]"

If you use custom psycopg2 adapters in your own code, rewrite them with the psycopg 3 Dumper/Loader API. See the full migration notes in CHANGELOG.md.

psycopg2 users: the 0.17.x branch is maintained for psycopg2 and receives bug fixes.

halfORM is a database-first ORM for PostgreSQL. You write the schema in SQL; halfORM introspects it at runtime and gives you Python objects to work with your data. No migrations, no code generation.

The central idea: a Relation object is a predicate. It describes the logical condition that rows must satisfy to belong to the relation. Its extension — the set of rows that currently satisfy the predicate in the database — is what you read, update, or delete.

Install

pip install half_orm

Configure

# ~/.half_orm/blog
[database]
name = blog
user = alice
password = secret
host = localhost

Usage

from half_orm.model import Model

blog = Model('blog')
Post   = blog.get_relation_class('blog.post')
Author = blog.get_relation_class('blog.author')

# Insert
alice = Author(
    first_name='Alice', last_name='Martin', email='[e-mail]'
).ho_insert()

# Query — Author(last_name='Martin') is the predicate "is an author named Martin"
for row in Author(last_name='Martin').ho_select('id', 'email'):
    print(row)

# Update a singleton (predicate identifies exactly one row)
Author(id=alice['id']).ho_assert_is_singleton().ho_update(email='[e-mail]')

# Delete
Author(id=alice['id']).ho_assert_is_singleton().ho_delete()

Documentation

• Learn halfORM in half an hour
• API Reference

License

halfORM is licensed under the GPL-3.0 license.