sessions.md

Sessions

The session object can be accessed through Models or Controllers in the same way. Here's how you'd set the email of a logged-in user in the session:

self.session["email"] = email

Once set in the session, this value will be accessible by the same client across requests:

email = self.session["email"]

You can access the session object indirectly in any template as well:

<p>Logged in as {{ session.email }}</p>

If you want to remove the variable from the session just do:

del self.session["email"]

Persistence

The way a session is persisted is configurable, it can be stored in memory, a file, or a database, for example. To configure the type of session persistence to use, pass the session_c keyword in the app initialization:

import appier

class HelloApp(appier.App):

    def __init__(self):
        appier.App.__init__(
            self,
            session_c = appier.session.FileSession
        )

HelloApp().serve()

The following session types are currently available:

• MemorySession - stores session values in memory (session is lost when the app is stopped and relaunched)
• FileSession - stores values in a Shelve named session.shelve.db in the app root directory (session is kept even if the app is stopped and relaunched)
• RedisSession - stores values in a Redis server should be used together with the REDISTOGO_URL configuration variable
• ClientSession - stores values using cookies on the client, this is considered safe (message signed) avoid tampering from the client side

Transient

To hold the session variables only for the duration of the request's lifecycle (eg: for authenticating the request with an OAuth token), transient session variables can be set using the set_t() method instead. These act just like regular session variables, therefore leveraging every other session-dependent feature for the duration of that request.

To set a transient session value:

self.session.set_t("email", "email")

To retrieve it later on you can just do a regular session value retrieval:

email = self.session["email"]

Or you may want to explicitly state that you are looking for a transient value (will not retrieve regular values):

self.session.get_t("email")

In case you want to delete it (not necessary in most cases, as it will be discarded at the end of the request):

self.session.delete_t("email")