Async Web API with FastAPI + SQLAlchemy 2.0

This is a sample project of Async Web API with FastAPI + SQLAlchemy 2.0. It includes asynchronous DB access using asyncpg and test code covering them.

This sample project is explained in this blog (written in Japanese).
https://www.rhoboro.com/2021/06/12/async-fastapi-sqlalchemy.html

If you want to use prisma instead of sqlalchemy, see rhoboro/async-fastapi-prisma.

Setup

Install

$ python3 -m venv venv
$ . venv/bin/activate
(venv) $ pip install -r requirements.lock

Setup a database and create tables

(venv) $ docker run -d --name db \
  -e POSTGRES_PASSWORD=password \
  -e PGDATA=/var/lib/postgresql/data/pgdata \
  -v pgdata:/var/lib/postgresql/data/pgdata \
  -p 5432:5432 \
  postgres:16.3-alpine

# Cleanup database
# $ docker stop db
# $ docker rm db
# $ docker volume rm pgdata

(venv) $ APP_CONFIG_FILE=local alembic upgrade head
INFO  [alembic.runtime.migration] Context impl PostgresqlImpl.
INFO  [alembic.runtime.migration] Will assume transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> a8483365f505, initial_empty
INFO  [alembic.runtime.migration] Running upgrade a8483365f505 -> 24104b6e1e0c, add_tables

Run

After start-up, you can access localhost:8000/docs to see the api documentation.

Using fastapi dev

The fastapi>=0.111.0 has a fastapi command.

(venv) $ APP_CONFIG_FILE=local fastapi dev
INFO:     Will watch for changes in these directories: ['/Users/rhoboro/go/src/github.com/rhoboro/async-fastapi-sqlalchemy/app']
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [49448] using WatchFiles
INFO:     Started server process [49450]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO     Using path app/main.py
INFO     Resolved absolute path /Users/rhoboro/go/src/github.com/rhoboro/async-fastapi-sqlalchemy/app/main.py
INFO     Searching for package file structure from directories with __init__.py files
INFO     Importing from /Users/rhoboro/go/src/github.com/rhoboro/async-fastapi-sqlalchemy

 ╭─ Python package file structure ─╮
 │                                 │
 │  📁 app                         │
 │  ├── 🐍 __init__.py             │
 │  └── 🐍 main.py                 │
 │                                 │
 ╰─────────────────────────────────╯

INFO     Importing module app.main
INFO     Found importable FastAPI app

 ╭── Importable FastAPI app ──╮
 │                            │
 │  from app.main import app  │
 │                            │
 ╰────────────────────────────╯

INFO     Using import string app.main:app

 ╭────────── FastAPI CLI - Development mode ───────────╮
 │                                                     │
 │  Serving at: http://127.0.0.1:8000                  │
 │                                                     │
 │  API docs: http://127.0.0.1:8000/docs               │
 │                                                     │
 │  Running in development mode, for production use:   │
 │                                                     │
 │  fastapi run                                        │
 │                                                     │
 ╰─────────────────────────────────────────────────────╯

INFO:     Will watch for changes in these directories: ['/Users/rhoboro/go/src/github.com/rhoboro/async-fastapi-sqlalchemy']
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [47967] using WatchFiles
INFO:     Started server process [47969]
INFO:     Waiting for application startup.
INFO:     Application startup complete.

Using uvicorn's multiprocess manager

The uvicorn>=0.30.0 has a new multiprocess manager.

(venv) $ APP_CONFIG_FILE=local uvicorn --workers 4 app.main:app                                                                                                                                                                 [main]
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started parent process [46740]
INFO:     Started server process [46744]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Started server process [46742]
INFO:     Waiting for application startup.
INFO:     Started server process [46745]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Application startup complete.
INFO:     Started server process [46743]
INFO:     Waiting for application startup.
INFO:     Application startup complete.

Test

(venv) $ pip install -r requirements_test.txt
(venv) $ black app
(venv) $ ruff app
(venv) $ mypy app
(venv) $ pytest app