BlackSheep-SQLAlchemy

Extension for BlackSheep that simplifies the use of SQLAlchemy in the web framework.

pip install blacksheep-sqlalchemy

Important: this library only supports rodi dependency injection container. However, the implementation can be used for reference to configure other DI containers to work with SQLAlchemy.

How to use

from blacksheep.server import Application
from blacksheepsqlalchemy import use_sqlalchemy

app = Application()

use_sqlalchemy(app, connection_string="<CONNECTION_STRING>")

After registering SQLAlchemy, services are configured in the application, so they are automatically resolved in any request handler requiring a SQLAlchemy db connection or db session; for example:

@get("/api/countries")
async def get_countries(db_connection) -> List[CountryData]:
    """
    Fetches the countries using a database connection.
    """
    result = []
    async with db_connection:
        items = await db_connection.execute(text("SELECT * FROM country"))
        for item in items.fetchall():
            result.append(CountryData(item["id"], item["name"]))
    return result

Services can be injected at any level of the resolution graph, so BlackSheep and rodi support out of the box the scenario of db connections or db sessions referenced in the business logic but not directly by the front-end layer (depending on programmers' preference and their notion of best practices when building web apps).

Services can be injected in the following ways:

By alias	By type annotation	Value
db_connection	AsyncConnection	instance of AsyncConnection (scoped to web request)
db_session	AsyncSession	instance of AsyncSession (scoped to web request)
db_engine	AsyncEngine	instance of AsyncEngine (singleton)

---

For example, using SQLite:

• requires driver: pip install aiosqlite
• connection string: sqlite+aiosqlite:///example.db

See the tests folder for a working example using database migrations applied with Alembic, and a documented API that offers methods to fetch, create, delete countries objects.

---

Note

BlackSheep is designed to be used in async way, therefore this library requires the use of an asynchronous driver.

References

• SQLAlchemy - support for asyncio

Documentation

Please refer to the documentation website.