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NAME

Dancer::Plugin::Auth::Twitter - Authenticate with Twitter

VERSION

version 0.07

SYNOPSIS

package SomeDancerApp;
use Dancer ':syntax';
use Dancer::Plugin::Auth::Twitter;

auth_twitter_init();

before sub {
    if (not session('twitter_user')) {
        redirect auth_twitter_authenticate_url;
    }
};

get '/' => sub {
    "welcome, ".session('twitter_user')->{'screen_name'};
};

get '/fail' => sub { "FAIL" };

...

CONCEPT

This plugin provides a simple way to authenticate your users through Twitter's OAuth API. It provides you with a helper to build easily a redirect to the authentication URI, defines automatically a callback route handler and saves the authenticated user to your session when done.

PREREQUESITES

In order for this plugin to work, you need the following:

  • Twitter application

    Anyone can register a Twitter application at http://dev.twitter.com/. When done, make sure to configure the application as a Web application.

  • Configuration

    You need to configure the plugin first: copy your consumer_key and consumer_secret (provided by Twitter) to your Dancer's configuration under plugins/Auth::Twitter:

      # config.yml
  ...
  plugins:
    "Auth::Twitter":
      consumer_key:     "1234"
      consumer_secret:  "abcd"
      callback_url:     "http://localhost:3000/auth/twitter/callback"
      callback_success: "/"
      callback_fail:    "/fail"
      engine:           Net::Twitter::Lite::WithAPIv1_1

    callback_success and callback_fail are optional and default to '/' and '/fail', respectively.

    The engine is optional as well. The supported engines are Net::Twitter and Net::Twitter::Lite::WithAPIv1_1 (Net::Twitter::Lite can also be used as a synonym for the latter). By default the plugin will use Net::Twitter::Lite::WithAPIv1_1.

    Note that you also need to provide your callback url, whose route handler is automatically created by the plugin.

  • Session backend

    For the authentication process to work, you need a session backend, in order for the plugin to store the authenticated user's information.

    Use the session backend of your choice, it doesn't make a difference, see Dancer::Session for details about supported session engines, or search the CPAN for new ones.

EXPORT

The plugin exports the following symbols to your application's namespace:

twitter

The plugin uses a Net::Twitter or Net::Twitter::Lite::WithAPIv1_1 object to do its job. You can access this object with the twitter symbol, exported by the plugin.

auth_twitter_init

This function should be called before your route handlers, in order to initialize the underlying Net::Twitter or Net::Twitter::Lite::WithAPIv1_1 object.

auth_twitter_authorize_url

This function returns an authorize URI for redirecting unauthenticated users. You should use this in a before filter like the following:

before sub {
    # we don't want to bounce for ever!
    return if request->path =~ m{/auth/twitter/callback};

    if (not session('twitter_user')) {
        redirect auth_twitter_authorize_url();
    }
};

When the user authenticate with Twitter's OAuth interface, she's going to be bounced back to /auth/twitter/callback.

auth_twitter_authenticate_url

Similar to auth_twitter_authorize_url, but this function instead returns an authenticate instead of authorize URI for redirecting unauthenticated users, which results in a slightly different behaviour.

See https://dev.twitter.com/pages/sign_in_with_twitter|here to learn about the differences.

ROUTE HANDLERS

The plugin defines the following route handler automatically

/auth/twitter/callback

This route handler is responsible for catching back a user that has just authenticated herself with Twitter's OAuth. The route handler saves tokens and user information in the session and then redirects the user to the URI specified by callback_success.

If the validation of the token returned by Twitter failed or was denied, the user will be redirect to the URI specified by callback_fail.

TIPS AND TRICKS

If you get the error

Net::Twitter::Role::OAuth::get_authorization_url(): 
    GET https://api.twitter.com/oauth/request_token failed: 500 
    Can't verify SSL peers without knowing which Certificate Authorities to trust

you can silence it by setting the environment variable PERL_LWP_SSL_VERIFY_HOSTNAME to 0.

ACKNOWLEDGEMENTS

This plugin has been written as a port of Catalyst::Authentication::Credential::Twitter written by Jesse Stay.

This plugin was part of the Perl Dancer Advent Calendar 2010.

AUTHORS

COPYRIGHT AND LICENSE

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.