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Dancer::Session::Abstract - abstract class for session engine


version 1.3521


This virtual class describes how to build a session engine for Dancer. This is done in order to allow multiple session storage backends with a common interface.

Any session engine must inherit from Dancer::Session::Abstract and implement the following abstract methods.


These settings control how a session acts.


The default session name is "dancer_session". This can be set in your config file:

    setting session_name: "mydancer_session"


Allows you to set the domain property on the cookie, which will override the default. This is useful for setting the session cookie's domain to something like so that the same cookie will be applicable and usable across subdomains of a base domain.


The user's session id is stored in a cookie. If true, this cookie will be made "secure" meaning it will only be served over https.


When the session should expire. The format is either the number of seconds in the future, or the human readable offset from "expires" in Dancer::Cookie.

By default, there is no expiration.


This setting defaults to 1 and instructs the session cookie to be created with the HttpOnly option active, meaning that JavaScript will not be able to access to its value.

Abstract Methods


Look for a session with the given id, return the session object if found, undef if not.


Create a new session, return the session object.


Write the session object to the storage engine.


Remove the current session object from the storage engine.

session_name (optional)

Returns a string with the name of cookie used for storing the session ID.

You should probably not override this; the user can control the cookie name using the session_name setting.


Retrieves the value associated with the key.

set_value($key, $value)

Stores the value associated with the key.

Inherited Methods

The following methods are not supposed to be overloaded, they are generic and should be OK for each session engine.


Build a new uniq id.


Reads the session ID from the cookie, ensuring it's syntactically valid.


Write the current session id to the dancer.session cookie.


Default is false. If true, session data will not be flushed after every modification and the session engine (or application) will need to ensure that a flush is called before the end of the request.



A Dancer::Session object represents a session engine and should provide anything needed to manipulate a session, whatever its storing engine is.


The session id will be written to a cookie, by default named dancer.session, it is assumed that a client must accept cookies to be able to use a session-aware Dancer webapp. (The cookie name can be change using the session_name config setting.)

storage engine

When the session engine is enabled, a before filter takes care to initialize the appropriate session engine (according to the setting session).

Then, the filter looks for a cookie named dancer.session (or whatever you've set the session_name setting to, if you've used it) in order to retrieve the current session object. If not found, a new session object is created and its id written to the cookie.

Whenever a session call is made within a route handler, the singleton representing the current session object is modified.

A flush is made to the session object after every modification unless the session engine overrides the is_lazy method to return true.


Dancer Core Developers


This software is copyright (c) 2010 by Alexis Sukrieh.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.