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Dancer2::Core::Role::SessionFactory - Role for session factories


version 0.163000


Any class that consumes this role will be able to store, create, retrieve and destroy session objects.

The default values for attributes can be overridden in your Dancer2 configuration. See "Session-engine" in Dancer2::Config.


The name of the cookie to create for storing the session key

Defaults to dancer.session

The domain of the cookie to create for storing the session key. Defaults to the empty string and is unused as a result.

The path of the cookie to create for storing the session key. Defaults to "/".

Default duration before session cookie expiration. If set, the Dancer2::Core::Session expires attribute will be set to the current time plus this duration (expression parsed by Dancer2::Core::Time).


Duration in seconds before sessions should expire, regardless of cookie expiration. If set, then SessionFactories should use this to enforce a limit on session validity.


Boolean flag to tell if the session cookie is secure or not.

Default is false.


Boolean flag to tell if the session cookie is http only.

Default is true.


Following is the interface provided by this role. When specified the required methods to implement are described.


Create a brand new session object and store it. Returns the newly created session object.

Triggers an exception if the session is unable to be created.

    my $session = MySessionFactory->create();

This method does not need to be implemented in the class.


Returns a randomly-generated, guaranteed-unique string. By default, it is a 32-character, URL-safe, Base64 encoded combination of a 32 bit timestamp and a 160 bit SHA1 digest of random seed data. The timestamp ensures that session IDs are generally monotonic.

The default algorithm is not guaranteed cryptographically secure, but it's still reasonably strong for general use.

If you have installed Math::Random::ISAAC::XS and Crypt::URandom, the seed data will be generated from a cryptographically-strong random number generator.

This method is used internally by create() to set the session ID.

This method does not need to be implemented in the class unless an alternative method for session ID generation is desired.


Return the session object corresponding to the session ID given. If none is found, triggers an exception.

    my $session = MySessionFactory->retrieve(id => $id);

The method _retrieve must be implemented. It must take $id as a single argument and must return a hash reference of session data.


Purges the session object that matches the ID given. Returns the ID of the destroyed session if succeeded, triggers an exception otherwise.

    MySessionFactory->destroy(id => $id);

The _destroy method must be implemented. It must take $id as a single argument and destroy the underlying data.


Make sure the session object is stored in the factory's backend. This method is called to notify the backend about the change in the session object.

The Dancer application will not call flush unless the session is_dirty attribute is true to avoid unnecessary writes to the database when no data has been modified.

An exception is triggered if the session is unable to be updated in the backend.

    MySessionFactory->flush(session => $session);

The _flush method must be implemented. It must take two arguments: the $id and a hash reference of session data.

Sets the session cookie into the response object

        response  => $response,
        session   => $session,
        destroyed => undef,

The response parameter contains a Dancer2::Core::Response object. The session parameter contains a Dancer2::Core::Session object.

The destroyed parameter is optional. If true, it indicates the session was marked destroyed by the request context. The default set_cookie_header method doesn't need that information, but it is included in case a SessionFactory must handle destroyed sessions differently (such as signalling to middleware).

Coerce a session object into a Dancer2::Core::Cookie object.

    MySessionFactory->cookie(session => $session);


Return a list of all session IDs stored in the backend. Useful to create cleaning scripts, in conjunction with session's creation time.

The _sessions method must be implemented. It must return an array reference of session IDs (or an empty array reference).


If there are configuration values specific to your session factory in your config.yml or environment, those will be passed to the constructor of the session factory automatically. In order to accept and store them, you need to define accessors for them.

          database_connection: "some_data"

In your session factory:

    package Dancer2::Session::Example;
    use Moo;
    with "Dancer2::Core::Role::SessionFactory";

    has database_connection => ( is => "ro" );

You need to do this for every configuration key. The ones that do not have accessors defined will just go to the void.


Dancer Core Developers


This software is copyright (c) 2015 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.