NAME

NAME
Dancer::Plugin::Deferred - Defer messages or data across redirections

VERSION
version 0.003

SYNOPSIS
use Dancer::Plugin::Deferred;

get '/defer' => sub {
deferred error => "Klaatu barada nikto";
redirect '/later';
}

get '/later' => sub {
template 'later';
}

# in template 'later.tt'
<% IF deferred.error %>
<div class="error"><% deferred.error %></div>
<% END %>

DESCRIPTION
This Dancer plugin provides a method for deferring a one-time message
across a redirect. It is similar to "flash" messages, but without the
race conditions that can result from multiple tabs in a browser or from
AJAX requests. It is similar in design to
Catalyst::Plugin::StatusMessage, but adapted for Dancer.

It works by creating a unique message ID within the session that holds
deferred data. The message ID is automatically added as a query
parameter to redirection requests. It's sort of like a session within a
session, but tied to a request rather than global to the browser. (It
will even chain across multiple redirects.)

When a template is rendered, a pre-template hook retrieves the data and
deletes it from the session. Alternatively, the data can be retrieved
manually (which will also automatically delete the data.)

Alternatively, the message ID parameters can be retrieved and used to
construct a hyperlink for a message to be retrieved later. In this case,
the message is preserved past the template hook. (The template should be
sure not to render the message if not desired.)

USAGE
deferred
deferred $key => $value;
$value = deferred $key; # also deletes $key

This function works just like "var" or "session", except that it lasts
only for the current request and across any redirects. Data is deleted
if accessed. If a key is set to an undefined value, the key is deleted
from the deferred data hash.

all_deferred
template 'index', { deferred => all_deferred };

This function returns all the deferred data as a hash reference and
deletes the stored data. This is called automatically in the
"before_template_render" hook, but is available if someone wants to have
manual control.

deferred_param
template 'index' => { link => uri_for( '/other', { deferred_param } ) };

This function returns the parameter key and value used to propagate the
message to another request. Using this function toggles the
"var_keep_key" variable to true to ensure the message remains to be
retrieved by the link.

CONFIGURATION
* "var_key: dpdid" -- this is the key in the "var" hash containing the
message ID

* "var_keep_key: dpd_keep" -- if this key in "var" is true, retrieving
values will not be destructive

* "params_key: dpdid" -- this is the key in the "params" hash
containing the message ID

* "session_key_prefix": dpd_> -- the message ID is appended to this
prefix and used to store deferred data in the session

* "template_key: deferred" -- this is the key to deferred data passed
to the template

SEE ALSO
* Dancer

* Dancer::Plugin::FlashMessage

* Dancer::Plugin::FlashNote

* Catalyst::Plugin::StatusMessage

ACKNOWLEDGMENTS
Thank you to mst for explaining why Catalyst::Plugin::StatusMessages
does what it does and putting up with my dumb ideas along the way.

SUPPORT
Bugs / Feature Requests
Please report any bugs or feature requests through the issue tracker at
<https://github.com/dagolden/dancer-plugin-deferred/issues>. You will be
notified automatically of any progress on your issue.

Source Code
This is open source software. The code repository is available for
public review and contribution under the terms of the license.

<https://github.com/dagolden/dancer-plugin-deferred>

git clone git://github.com/dagolden/dancer-plugin-deferred.git

AUTHOR
David Golden <[email protected]>

COPYRIGHT AND LICENSE
This software is Copyright (c) 2012 by David Golden.

This is free software, licensed under:

The Apache License, Version 2.0, January 2004