Using the Session ¶

The functions and macros to manipulate the session are defined in the REBLOCKS/SESSION package.

Session initialization

When a new user opens the site in the browser, Reblocks does these steps:

• Creates a new session object. You can consider it a hash table where some data could be stored.

• Generates an unique id and put's this session object to the hash map of all sessions.

• Calls the init generic function to determine what widget should be shown to the user.

• Renders the root widget to HTML and sends it to the browser.

• Along with this HTML response, sends Set-Cookie header to save session id in the browser.

The method you define for init generic-function should return a root widget. This widget may include children and render them in it's reblocks/widget:render generic-function implementation.

You will find an example of init in the Quickstart section.

Storing data

You can store any kind of data in a session.

To set a value, use (SETF GET-VALUE) function.

For example, you might want to store information about the current user if he logged in:

API

• [macro]
  reblocks/session:with-session
  (env) &body body

  Sets dynamic binding for session and env

• [function]
  reblocks/session:get-value
  key &optional default

  Get a session value from the currently running webapp. KEY is compared using EQUAL.

• [function]
  reblocks/session:delete-value
  key

  Clear the session value for the currently running app.

  KEY is compared using EQUAL.

• [function]
  reblocks/session:gen-id
  &OPTIONAL (PREFIX "dom")

  Generates an ID unique accross the session. The generated ID can be used to create IDs for html elements, widgets, etc.

• [function]
  reblocks/session:in-session-p

  Checks if session is active and data can be safely retrived or stored.

• [generic-function]
  reblocks/session:init
  app

  A method for this generic function should be defined to initialize application for a new user session.

  It should return a widget which become a root widget.

• [function]
  reblocks/session:get-session-id

  Returns current session id or signals an error if no current session.

• [function]
  reblocks/session:reset

  Reset current session.

• [function]
  reblocks/session:expire

  Deletes current session id for the browser.

  On the next HTTP request a new session will be created.

• [function]
  reblocks/session:get-number-of-sessions

• [function]
  reblocks/session:make-session-middleware
  &key (samesite-policy :lax)

• [function]
  reblocks/session:get-number-of-anonymous-sessions