Flask middleware for specific route

There are a few ways how to add custom processing before specific endpoint.

1) Using python decorator:

from functools import wraps

def home_decorator():
    def _home_decorator(f):
        @wraps(f)
        def __home_decorator(*args, **kwargs):
            # just do here everything what you need
            print('before home')
            result = f(*args, **kwargs)
            print('home result: %s' % result)
            print('after home')
            return result
        return __home_decorator
    return _home_decorator


@app.route('/home')
@home_decorator()
def home():
    return 'Hello'

2) Using before_request

@app.before_request
def hook():
    # request - flask.request
    print('endpoint: %s, url: %s, path: %s' % (
        request.endpoint,
        request.url,
        request.path))
    # just do here everything what you need...

3) Using middleware. Just add condition on request path.

class Middleware:

    def __init__(self, app):
        self.app = app

    def __call__(self, environ, start_response):
        # not Flask request - from werkzeug.wrappers import Request
        request = Request(environ)
        print('path: %s, url: %s' % (request.path, request.url))
        # just do here everything what you need
        return self.app(environ, start_response)


@app.route('/home')
def home():
    return 'Hello'


app.wsgi_app = Middleware(app.wsgi_app)

4) Also you can use before_request_funcs to set list of functions before specific blueprint.

api = Blueprint('my_blueprint', __name__)


def before_my_blueprint():
    print(111)


@api.route('/test')
def test():
    return 'hi'


app.before_request_funcs = {
    # blueprint name: [list_of_functions]
    'my_blueprint': [before_my_blueprint]
}

app.register_blueprint(api)