FastAPI¶

This section describes integration with FastAPI ASGI framework.

Note

FastAPI also provides OpenAPI support. The main difference is that, unlike FastAPI’s code-first approach, OpenAPI-core allows you to laverage your existing specification that alligns with API-First approach. You can read more about API-first vs. code-first in the Guide to API-first.

Middleware¶

FastAPI can be integrated by middleware to apply OpenAPI validation to your entire application.

Add FastAPIOpenAPIMiddleware with OpenAPI object to your middleware list.

  from fastapi import FastAPI
  from openapi_core.contrib.fastapi.middlewares import FastAPIOpenAPIMiddleware

  app = FastAPI()
  app.add_middleware(FastAPIOpenAPIMiddleware, openapi=openapi)

After that all your requests and responses will be validated.

Also you have access to unmarshal result object with all unmarshalled request data through openapi scope of request object.

async def homepage(request):
   # get parameters object with path, query, cookies and headers parameters
   unmarshalled_params = request.scope["openapi"].parameters
   # or specific location parameters
   unmarshalled_path_params = request.scope["openapi"].parameters.path

   # get body
   unmarshalled_body = request.scope["openapi"].body

   # get security data
   unmarshalled_security = request.scope["openapi"].security

Response validation¶

You can skip response validation process: by setting response_cls to None

  app = FastAPI()
  app.add_middleware(
      FastAPIOpenAPIMiddleware,
      openapi=openapi,
      response_cls=None,
  )

Low level¶

For low level integration see Starlette integration.