flask.md

Flask

This section describes integration with the Flask web framework. The integration supports Flask versions 2 and 3.

View decorator

Flask can be integrated using a view decorator to apply OpenAPI validation to your application's specific views.

Use FlaskOpenAPIViewDecorator with the OpenAPI object to create the decorator.

from openapi_core.contrib.flask.decorators import FlaskOpenAPIViewDecorator

openapi_validated = FlaskOpenAPIViewDecorator(openapi)

@app.route('/home')
@openapi_validated
def home():
    return "Welcome home"

You can skip the response validation process by setting response_cls to None.

from openapi_core.contrib.flask.decorators import FlaskOpenAPIViewDecorator

openapi_validated = FlaskOpenAPIViewDecorator(
    openapi,
    response_cls=None,
)

If you want to decorate a class-based view, you can use the decorators attribute:

class MyView(View):
    decorators = [openapi_validated]

    def dispatch_request(self):
        return "Welcome home"

app.add_url_rule('/home', view_func=MyView.as_view('home'))

View

As an alternative to the decorator-based integration, Flask method-based views can be integrated by inheriting from the FlaskOpenAPIView class.

from openapi_core.contrib.flask.views import FlaskOpenAPIView

class MyView(FlaskOpenAPIView):
    def get(self):
        return "Welcome home"

app.add_url_rule(
    '/home',
    view_func=MyView.as_view('home', spec),
)

Additional customization parameters can be passed to the view.

from openapi_core.contrib.flask.views import FlaskOpenAPIView

class MyView(FlaskOpenAPIView):
    def get(self):
        return "Welcome home"

app.add_url_rule(
    '/home',
    view_func=MyView.as_view(
        'home', spec,
        extra_format_validators=extra_format_validators,
    ),
)

Request parameters

In Flask, all unmarshalled request data are provided as the Flask request object's openapi.parameters attribute.

from flask.globals import request

@app.route('/browse/<id>/')
@openapi
def browse(id):
    browse_id = request.openapi.parameters.path['id']
    page = request.openapi.parameters.query.get('page', 1)

    return f"Browse {browse_id}, page {page}"

Low level

You can use FlaskOpenAPIRequest as a Flask request factory:

from openapi_core.contrib.flask import FlaskOpenAPIRequest

openapi_request = FlaskOpenAPIRequest(flask_request)
result = openapi.unmarshal_request(openapi_request)

For the response factory, see the Werkzeug integration.