Some notes on developing a web application with FastAPI.
Testing#
FastAPI provides a fastapi.testclient module to help us test the application.
# content of application.py
from fastapi import FastAPI
app = FastAPI()
@app.get("/")
def index():
return {'msg': 'hello world!'}
You can test the endpoints with TestClient class from testclient module.
# content of test_application.py
from application import app
from fastapi.testclient import TestClient
from fastapi import status
client = TestClient(app)
def test_root():
response = app.get('/')
assert response.status_code == status.HTTP_200_OK
assert response.json() == {'msg': 'hello world!'}
Then you can test your application with pytest:
pytest .
ref:
Generate OpenAPI specification#
The app we create using FastAPI has a openapi() method.
Under the hood, it is calling the get_openapi() method from the module fastapi.openapi.utils.
We can override this method to customize the OpenAPI schema.
# content of application.py
from fastapi import FastAPI
from fastapi.openapi.utils import get_openapi
app = FastAPI()
@app.get("/")
def index():
return {'msg': "hello world"}
def custom_openapi():
if app.openapi_schema:
return app.openapi_schema
openapi_schema = get_openapi(
title="My Awesome Application",
version=app.version,
contact={
"name": "Your Name",
"email": "your_name@host.com",
"url": "https://www.example.com"
},
openapi_version=app.openapi_version,
summary="This implements my awesome application with fastAPI",
description="""
some long description about your application.
""",
routes=app.routes,
)
app.openapi_schema = openapi_schema
return app.openapi_schema
app.openapi = custom_openapi
Then if you want to generate the OpenAPI spec, it is easy:
# content of generate_openapi_spec.py
import json
from application import app
with open('path/to/openapi.json', 'w') as f:
json.dump(app.openapi(), indent=4)
ref:
- generate OpenAPI programmatically: https://github.com/tiangolo/fastapi/discussions/7690
- https://fastapi.tiangolo.com/how-to/extending-openapi/