Flask `RuntimeError: Working outside of application context.` from Middleware

Question

Here is the Middleware class:

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


    def __call__(self, environ, start_response):
        request = Request(environ)
        cookies = request.cookies
        path = request.path

        environ['isAuthenticated'] = isAuthenticated(cookies)

        return self.app(environ, start_response)


def isAuthenticated(cookies):
    if (len(cookies)) > 0 :
        if 'jwt' in cookies:
            payload = decodeJWT(cookies['jwt'])
            connection = connect_db()
            
            
            return payload
    else:
        return False

And here is the ConnectDB.py:

def connect_db():
    host = current_app.config['HOST']
    db = current_app.config['DB']
    username = current_app.config['USERNAME']
    password = current_app.config['PASSWORD']
    
    connection = psycopg2.connect(host=host, database=db, user=username, password=password, port=5432, cursor_factory=RealDictCursor)
    return connection

I'm provoking the middleware likes this:

app = Flask(__name__)
app.config.from_object('SETTINGS')
app.wsgi_app = Middleware(app.wsgi_app)

And I'm getting this error:

RuntimeError: Working outside of application context.

This typically means that you attempted to use functionality that needed
to interface with the current application object in some way. To solve
this, set up an application context with app.app_context().  See the
documentation for more information.

I know that I need to call connect_db from within the app context to access the DB credentials but how can I access it from inside the Middleware class?

https://stackoverflow.com/questions/31444036/runtimeerror-working-outside-of-application-context — charchit, Jul 23 '21 at 16:47

score 1 · Accepted Answer · answered Jul 24 '21 at 12:21

Figured it out, I had to pass the actual or fullapp intoMiddlewarenot just thewsgi` like this:

app = Flask(__name__)
app.config.from_object('SETTINGS')
app.wsgi_app = Middleware(app.wsgi_app, app)

and then Middleware becomes like this:

class Middleware:
    def __init__(self, wsgi, app):
        self.wsgi = wsgi
        self.app = app


    def __call__(self, environ, start_response):
        request = Request(environ)
        cookies = request.cookies
        path = request.path

        with self.app.app_context():
            environ['isAuthenticated'] = isAuthenticated(cookies)

        return self.wsgi(environ, start_response)

Flask `RuntimeError: Working outside of application context.` from Middleware

1 Answers1