How to set FastAPI version to allow HTTP specifying version in accept header?

Question

I am working on a project that requires to version FastAPI endpoints. We want to version the endpoint through HTTP accept header, for example:

headers={'Accept': 'application/json;version=1.0.1'}, 
headers={'Accept': 'application/json;version=1.0.2'}

Setting up the api version like this seem not work:

app = FastAPI(
        version=version,
        title="A title",
        description="Some description.",
    )

Does anyone know what else I need to do with this ?

Answer 1

Well maybe the version in path url could be better

sub apps docs

from fastapi import FastAPI

app = FastAPI()
v1 = FastAPI()

@v1.get("/app/")
def read_main():
    return {"message": "Hello World from api v1"}

v2 = FastAPI()

@v2.get("/app/")
def read_sub():
    return {"message": "Hello World from  api v2"}

app.mount("/api/v1", v1)
app.mount("/api/v2", v2)

You will see the auto docs for each app

localhost:8000/api/v1/docs

localhost:8000/api/v2/docs

But you always get the headers in request

from starlette.requests import Request

from fastapi import FastAPI
app = FastAPI()

@app.post("/hyper_mega_fast_service")
def fast_service(request: Request, ):

    aceept = request.headers.get('Accept')

    value = great_fuction_to_get_version_from_header(aceept)
    if value == '1.0.1': 
        "Do something"
        
    if value == '1.0.2': 
        "Do something"

Answer 2

Try api versioning for fastapi web applications

Installation

pip install fastapi-versioning

Examples

from fastapi import FastAPI
from fastapi_versioning import VersionedFastAPI, version

app = FastAPI(title="My App")


@app.get("/greet")
@version(1, 0)
def greet_with_hello():
    return "Hello"


@app.get("/greet")
@version(1, 1)
def greet_with_hi():
    return "Hi"


app = VersionedFastAPI(app)

this will generate two endpoints:

/v1_0/greet
/v1_1/greet

as well as:

/docs
/v1_0/docs
/v1_1/docs
/v1_0/openapi.json
/v1_1/openapi.json

There's also the possibility of adding a set of additional endpoints that redirect the most recent API version. To do that make the argument enable_latest true:

app = VersionedFastAPI(app, enable_latest=True)

this will generate the following additional endpoints:

/latest/greet
/latest/docs
/latest/openapi.json

In this example, /latest endpoints will reflect the same data as /v1.1.

Try it out:

pip install pipenv
pipenv install --dev
pipenv run uvicorn example.annotation.app:app
# pipenv run uvicorn example.folder_name.app:app

Usage without minor version

from fastapi import FastAPI
from fastapi_versioning import VersionedFastAPI, version

app = FastAPI(title='My App')

@app.get('/greet')
@version(1)
def greet():
  return 'Hello'

@app.get('/greet')
@version(2)
def greet():
  return 'Hi'

app = VersionedFastAPI(app,
    version_format='{major}',
    prefix_format='/v{major}')

this will generate two endpoints:

/v1/greet
/v2/greet

as well as:

/docs
/v1/docs
/v2/docs
/v1/openapi.json
/v2/openapi.json

Extra FastAPI constructor arguments

It's important to note that only the title from the original FastAPI will be provided to the VersionedAPI app. If you have any middleware, event handlers etc these arguments will also need to be provided to the VersionedAPI function call, as in the example below

from fastapi import FastAPI, Request
from fastapi_versioning import VersionedFastAPI, version
from starlette.middleware import Middleware
from starlette.middleware.sessions import SessionMiddleware

app = FastAPI(
    title='My App',
    description='Greet uses with a nice message',
    middleware=[
        Middleware(SessionMiddleware, secret_key='mysecretkey')
    ]
)

@app.get('/greet')
@version(1)
def greet(request: Request):
    request.session['last_version_used'] = 1
    return 'Hello'

@app.get('/greet')
@version(2)
def greet(request: Request):
    request.session['last_version_used'] = 2
    return 'Hi'

@app.get('/version')
def last_version(request: Request):
    return f'Your last greeting was sent from version {request.session["last_version_used"]}'

app = VersionedFastAPI(app,
    version_format='{major}',
    prefix_format='/v{major}',
    description='Greet users with a nice message',
    middleware=[
        Middleware(SessionMiddleware, secret_key='mysecretkey')
    ]
)