Quart-SQLAlchemy

Quart-SQLAlchemy provides a simple wrapper for SQLAlchemy made for humans. I've kept things as simple as possible, abstracted much complexity, and implemented everything using the current best practices recommended by the SQLAlchemy developers and targets version 2.0.x+. As a convenience, a framework adapter is provided for Quart, but the rest of this library is framework agnostic.

The bundled SQLAlchemy object intentionally discards the use of scoped_session and it's async counterpart. With version 2.x+, it's expected that sessions are short lived and vanilla and context managers are used for managing sesssion lifecycle. Any operations that intend to change state should open an explicit transaction using the context manager returned by session.begin(). This pattern of usage prevents problems like sessions being shared between processes, threads, or tasks entirely, as opposed to the past conventions of mitigating this type of sharing. Another best practice is expecting any transaction to intermittently fail, and structuring your logic to automatically perform retries. You can find the retrying session context managers in the retry module.

Installing

Install and update using pip:

$ pip install quart-sqlalchemy

Install the latest release with unreleased pytest-asyncio fixes:

$ pip install git+ssh://[email protected]/joeblackwaslike/quart-sqlalchemy.git#egg=quart_sqlalchemy

Install a wheel from our releases:

$ pip install https://github.com/joeblackwaslike/quart-sqlalchemy/releases/download/v3.0.1/quart_sqlalchemy-3.0.1-py3-none-any.whl

Add to requirements.txt:

quart-sqlalchemy @ https://github.com/joeblackwaslike/quart-sqlalchemy/releases/download/v3.0.1/quart_sqlalchemy-3.0.1-py3-none-any.whl

A Simple Example

import sqlalchemy as sa
import sqlalchemy.orm
from sqlalchemy.orm import Mapped, mapped_column
from quart import Quart

from quart_sqlalchemy import SQLAlchemyConfig
from quart_sqlalchemy.framework import QuartSQLAlchemy

app = Quart(__name__)

db = QuartSQLAlchemy(
  config=SQLAlchemyConfig(
      binds=dict(
          default=dict(
              engine=dict(
                  url="sqlite:///",
                  echo=True,
                  connect_args=dict(check_same_thread=False),
              ),
              session=dict(
                  expire_on_commit=False,
              ),
          )
      )
  ),
  app=app,
)

class User(db.Model)
    __tablename__ = "user"

    id: Mapped[int] = mapped_column(sa.Identity(), primary_key=True, autoincrement=True)
    username: Mapped[str] = mapped_column(default="default")

db.create_all()

with db.bind.Session() as s:
    with s.begin():
        user = User(username="example")
        s.add(user)
        s.flush()
        s.refresh(user)

    users = s.scalars(sa.select(User)).all()

print(user, users)
assert user in users

Contributing

For guidance on setting up a development environment and how to make a contribution to Quart-SQLAlchemy, see the contributing guidelines.