How can I access session data in middleware?

[ipimpat]

Sorry for my newbie question, but I'm a Python novice, and no experience with Flask.

I'm trying to make a middleware plugin that prevents anonymous access to my CKAN site, but I'm also using the ldap extension, so I need to check if the ckanext-ldap-user session key is set to determine if the user is logged in.

Gist: https://gist.github.com/ipimpat/5b9614db4c1e4794cc5d50a347e4a8ef

How ever I get this error when trying to access the session:

an | TypeError: No object (name: session) has been registered for this thread

In my code I have this method which should check if the ckanext-ldap-user session key exists.

In the top of my code I'm importing the session variable

from ckan.common import config, session

And then try to use it like this

    def _is_logged_in(self, environ):
        # check if the request belongs to an authenticated session
        if 'ckanext-ldap-user' in session:        # <-- this breaks
            return True
        elif 'repoze.who.identity' in environ:
            return True

        return False

[frafra]

session is not defined, as the error says. You just have self and environ available.

[ipimpat]

session is not defined, as the error says.

Updated my question - I do import it, sorry I did not mention that.

[smotornyuk]

session is a request-specific variable that is initialized by flask for the functions that handle requests. There are other similar variables in CKAN common, like request, g.
You should never use them outside the view functions/blueprints.

Middleware it's a wrapper around application, not just some functions that are called before the request and after the request. That's why you should not use tools from the inside of application as a part of your middleware

Either move the logic of your middleware to a different place(Flask's app.before_request hook) or use only the environ variable(headers, cookies) inside __call__ method of your middleware.
PS there is a way to use sessions inside middleware, but it's a really bad thing to do, so I prefer not to share this knowledge 😆

[ipimpat]

session is a request-specific variable that is initialized by flask for the functions that handle requests. There are other similar variables in CKAN common, like request, g.
You should never use them outside the view functions/blueprints.

Thanks for the advice, as I mentioned in the beginning of my question, I'm a Python novice, so I'm ignorant about that stuff (I have some experience with Laravel/PHP).

Either move the logic of your middleware to a different place(Flask's app.before_request hook)

Could you provide a bit of boiler plate code to get me startet - just the "entry point" part ?

PS there is a way to use sessions inside middleware, but it's a really bad thing to do, so I prefer not to share this knowledge laughing

I must admit I'm curious to see it, to better understand why it's a bad idea.

[ipimpat]

Either move the logic of your middleware to a different place(Flask's app.before_request hook)

Could you provide a bit of boiler plate code to get me startet - just the "entry point" part ?

Never mind, I think I worked it out, is this what you are thinking about?

    def __call__(self, environ, start_response):

        @self.app.before_request
        def before_request_callback():
            log.info(session)   # <--  works

[smotornyuk]

Yep, exactly

And, as for a fast dirty way to use sessions inside middleware, you can rewrite it to something like:

class Middleware:
    session = None

    def __init__(self, app, app_conf):
        import ckan.common
        app.before_request(lambda: setattr(self, 'session', dict(ckan.common.session))


    def __call__(self, environ, start_response):
         log.info(self.session)

In that way, you are copying session data into middleware for each request. But as it's only a copy and we have to use before_request anyway, it's better to do as per your last comment