Sustained.py

A Python query builder and lightweight ORM inspired by Objection.js.

You describe a query as chained Python methods. Sustained renders the SQL for your dialect, runs it parameterized against any DB-API 2.0 connection or pool, and hydrates the rows into your model classes.

adults = User.query().where(User.c.age >= 18).orderBy('name').run()

What it does

SQL building for the default (ANSI), Postgres, MSSQL, Presto, AWS Athena, and DuckDB dialects: joins, CTEs (including recursive), unions, window functions, CASE expressions, and subqueries. Features a dialect lacks raise DialectError at build time.
Safe execution: every statement runs parameterized. Transactions nest through savepoints. update() and delete() refuse to run without a WHERE clause.
Writes: insert(), update(), delete(), upserts with onConflict(), INSERT ... SELECT, CTAS, and RETURNING.
Typed filters: User.query().where((User.c.age > 21) & User.c.name.like('A%')).
Results as model instances, dicts, pandas DataFrames, or pyarrow Tables, with withGraphFetched() eager loading.
Schema migrations: models declare typed columns and indexes; Migrator.sync(models) diffs the live database, generates the migration, applies it, and down() rolls it back. Destructive changes are gated behind explicit opt-ins.
Async: the same queries run through driver adapters (asyncpg, aiosqlite, or any sync driver in a worker thread) with await query.arun().

What it does not do

No lazy loading, no dirty tracking or save(), no identity map, no result caching, no cross-dialect emulation of missing features, and no guessed migrations: drops, renames, and NOT NULL backfills all require explicit opt-ins or hints. Writes and schema changes only happen when you spell them out.

Installation

python3 -m pip install sustained

Usage

from sustained import Model, RelationType

class Person(Model):
    tableName = 'persons'

class Animal(Model):
    tableName = 'animals'
    relationMappings = {
        'owner': {
            'relation': RelationType.BelongsToOneRelation,
            'modelClass': Person,
            'join': {
                'from': 'animals.ownerId',
                'to': 'persons.id'
            }
        }
    }

# Build a query
query = Animal.query().select('animals.name', 'persons.name').leftOuterJoinRelated('owner')

print(query)
# SELECT animals.name, persons.name
# FROM animals
# LEFT OUTER JOIN persons
#   ON animals.ownerId = persons.id


# Execute against any DB-API 2.0 connection
import sqlite3

conn = sqlite3.connect('app.db')
Animal.bind(conn)

# Parameterized execution with model hydration
animals = Animal.query().where('species', '=', 'dog').orderBy('name').run()

# Or take the SQL and parameters and execute them yourself
sql, params = Animal.query().where('species', '=', 'dog').to_sql()
# sql:    "SELECT * FROM animals WHERE species = ?"
# params: ('dog',)

Models can manage their own schema:

from sustained.migrations import Migrator
from sustained.schema import Integer, String, Text

class User(Model):
    tableName = 'users'
    tableColumns = {
        'id': Integer(primary_key=True, autoincrement=True),
        'email': String(120, unique=True, nullable=False),
    }

migrator = Migrator(conn, [])
migrator.sync([User])              # creates the users table

User.tableColumns['bio'] = Text()
migrator.sync([User])              # adds only the bio column
migrator.down()                    # rolls it back

Documentation

The documentation covers models, queries, dialects and drivers, filtering, grouping, relations and joins, execution, pooling, and async, and schema and migrations. The API reference lists every public method by task.

Development

To install from source:

git clone https://github.com/wetherc/sustained.git
cd sustained
python3 -m pip install -e .

This project uses pre-commit to format code, lint, type check, and run the test suite before each commit:

pip install pre-commit
pre-commit install

Release files for sustained 2.9.0

For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.

Source distribution (sdist)

Source distribution for sustained 2.9.0
File	Size	Uploaded
sustained-2.9.0.tar.gz	166.3 kB	Aug 15, 2026	Details

Built distribution (wheel)

Table of built distributions (wheels) for sustained 2.9.0
File	Interpreter	ABI	Platform	Reset
sustained-2.9.0-py3-none-any.whl 99.7 kB Aug 15, 2026	Python 3	none	any	Details

Total release size: 266.0 kB

Release files / sustained-2.9.0.tar.gz

Download URL	sustained-2.9.0.tar.gz
Size	166.3 kB
Tags	Source
SHA-256 checksum How to use checksums	`d9b16586199c07be6c82b7e55e366ce0e2c1bb0a26ae26a1a32dd1dd0a5e59cb`
BLAKE2b-256 checksum How to use checksums	`168598d28ce5b41cbd897cef45f8733cf3d3ab7707f047a7fd2639e742c557e4`
Upload date	Aug 15, 2026
Uploaded using Trusted Publishing? What is trusted publishing?	No
Uploaded via	`twine/7.0.0 CPython/3.13.0`

Release files / sustained-2.9.0-py3-none-any.whl

Download URL	sustained-2.9.0-py3-none-any.whl
Size	99.7 kB
Tags	Python 3
SHA-256 checksum How to use checksums	`8ac9eaf5d2969183c91fd572da033b3c434adac550350cebdfa393b95f815ebf`
BLAKE2b-256 checksum How to use checksums	`fdcf62b8aaa0255090c4ee19b6a7e5e5a0f5cc0d8fdbbb52e4070883b24e6a12`
Upload date	Aug 15, 2026
Uploaded using Trusted Publishing? What is trusted publishing?	No
Uploaded via	`twine/7.0.0 CPython/3.13.0`