Using FastAPI with Async SQLAlchemy 2.0

• Introduction
• Installation
• Usage
  • Local Postgres server using Docker
  • Use SQLite instead of PostgreSQL
• License

Introduction

I've been using FastAPI and SQLAlchemy combined with encode/databases for a while now.

The databases package is a great wrapper around SQLAlchemy that allows you to use async/await with SQLAlchemy.

However, this does not seem be be actively maintained anymore. So I decided to give the new Async SQLAlchemy a try instead.

This repository contains a very simple example how to use FastAPI with Async SQLAlchemy 2.0.

Installation

Clone the repository and install the dependencies. This project uses Poetry for dependency management which should be installed on your system first.

poetry install

Then switch to the virtual environment:

poetry shell

Usage

Run the server using Uvicorn:

uvicorn main:app --reload

You can also run the server by just executing the main.py file:

python main.py

Then open your browser at http://localhost:8000.

There is only one endpoint available: /users. It returns a list of all users for a GET request and creates a new user for a POST request.

Local Postgres server using Docker

This example uses PostgreSQL as the database. If you dont have a local PostgreSQL database running, you can start one with Docker using the following command:

docker run \
  --rm   \
  --name  postgres \
  -p 5432:5432 \
  -e POSTGRES_USER=postgres \
  -e POSTGRES_PASSWORD=postgres \
  -e POSTGRES_DB=postgres \
  -d postgres

This will run a PostgreSQL database in a Docker container in the background. When you are finished and want to stop the database, run:

docker stop postgres

If needed, you can connect to the database managment by :

docker exec -it postgres psql -U postgres

This will allow you to edit or delete the database or records.

Use SQLite instead of PostgreSQL

For testing purposes, you can also use SQLite instead of PostgreSQL. To do so, open the dp.py file and comment out the PostgreSQL database in the DATABASE_URL environment variable and uncomment the SQLite database.

# DATABASE_URL = "postgresql+asyncpg://postgres:postgres@localhost/postgres"
DATABASE_URL = "sqlite+aiosqlite:///./test.db"

License

This project is licensed under the terms of the MIT license.

MIT License

Copyright (c) 2023-2024 Grant Ramsay

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.