+---

+date: 2009-05-13T00:00:00Z

+summary: In which we reach the conclusion on how to write a feed aggregator.

+title: A simple feed aggregator with modern Perl - part 4

+---

+

+We have the model, the aggregator (and some tests), now we can do a basic frontend to read our feed. For this I will create a webapp using [Catalyst](http://www.catalystframework.org).

+

+[Catalyst::Devel](http://search.cpan.org/perldoc?Catalyst::Devel) is required for developping catalyst application, so we will install it first:

+

+```perl

+% cpan Catalyst::Devel

+```

+

+Now we can create our catalyst application using the helper:

+

+```perl

+% catalyst.pl MyFeedReader

+```

+

+This command initialise the framework for our application **MyFeedReader**. A number of files are created, like the structure of the MVC directory, some tests, helpers, ...

+

+We start by creating a view, using [TTSite](http://search.cpan.org/perldoc?Catalyst::View::TT). TTSite generate some templates for us, and the configuration for this template. We will also have a basic CSS, a header, footer, etc.

+

+```bash

+cd MyFeedReader

+perl script/myfeedreader_create.pl view TT TTSite

+```

+

+TTSite files are under **root/src** and **root/lib**. A **MyAggregator/View/TT.pm** file is also created. We edit it to make it look like this:

+

+```perl

+__PACKAGE__->config({

+ INCLUDE_PATH => [

+ MyFeedReader->path_to( 'root', 'src' ),

+ MyFeedReader->path_to( 'root', 'lib' )

+ ],

+ PRE_PROCESS => 'config/main',

+ WRAPPER => 'site/wrapper',

+ ERROR => 'error.tt2',

+ TIMER => 0,

+ TEMPLATE_EXTENSION => '.tt2',

+});

+```

+

+Now we create our first template, in **root/src/index.tt2**

+

+```html

+to <a href="/feed/">your feeds</a>

+```

+

+If you start the application (using `perl script/myfeedreader_server.pl`) and point your browser on http://localhost:3000/, this template will be rendered.

+

+We need two models, one for KiokuDB and another one for MyModel:

+

+**lib/MyFeedReader/Model/KiokuDB.pm**

+

+```perl

+package MyFeedReader::Model::KiokuDB;

+use Moose;

+BEGIN { extends qw(Catalyst::Model::KiokuDB) }

+1;

+```

+

+we edit the configuration file (**myfeedreader.conf**), and set the dsn for our kiokudb backend

+

+```xml

+ <Model KiokuDB>

+ dsn dbi:SQLite:../MyAggregator/foo.db

+ </Model>

+```

+

+**lib/MyFeedReader/Model/MyModel.pm**

+

+```perl

+package MyFeedReader::Model::MyModel;

+use base qw/Catalyst::Model::DBIC::Schema/;

+1;

+```

+

+and the configuration:

+

+```xml

+<Model MyModel>

+ connect_info dbi:SQLite:../MyModel/model.db

+ schema_class MyModel

+</Model>

+```

+

+We got our view and our model, we can do the code for the controller. We need 2 controller, one for the feed, and one for the entries. The Feed controller will list them and display entries titles for a given feed. The Entry controller will just display them.

+

+**lib/MyFeedReader/Controller/Feed.pm**

+

+```perl

+package MyFeedReader::Controller::Feed;

+use strict;

+use warnings;

+use parent 'Catalyst::Controller';

+

+__PACKAGE__->config->{namespace} = 'feed';

+

+sub index : Path : Args(0) {

+ my ( $self, $c ) = @_;

+ $c->stash->{feeds}

+ = [ $c->model('MyModel')->resultset('Feed')->search() ];

+}

+

+sub view : Chained('/') : PathPart('feed/view') : Args(1) {

+ my ( $self, $c, $id ) = @_;

+ $c->stash->{feed}

+ = $c->model('MyModel')->resultset('Feed')->find($id);

+}

+

+1;

+```

+

+The function `index` list the feeds, while the function `view` list the entries for a give feed. We use the chained action mechanism to dispatch this url, so we can have urls like this **/feed/\***

+

+We create our 2 templates (for index and view):

+

+**root/src/feed/index.tt2**

+

+```html

+<ul>

+ [% FOREACH feed IN feeds %]

+ <li><a href="/feed/view/[% feed.id %]">[% feed.url %]</a></li>

+ [% END %]

+</ul>

+```

+

+**root/src/feed/vew.tt2**

+

+```html

+<h1>[% feed.url %]</h1>

+

+<h3>entries</h3>

+<ul>

+ [% FOREACH entry IN feed.entries %]

+ <li><a href="/entry/[% entry.id %]">[% entry.permalink %]</a></li>

+ [% END %]

+</ul>

+```

+

+If you point your browser to http://localhost:3000/feed/ you will see this:

+

+<img src='/imgs/list_feed.webp' alt='list feeds'>

+

+Now the controller for displaying the entries:

+

+```perl

+package MyFeedReader::Controller::Entry;

+use strict;

+use warnings;

+use MyAggregator::Entry;

+use parent 'Catalyst::Controller';

+

+__PACKAGE__->config->{namespace} = 'entry';

+

+sub view : Chained('/') : PathPart('entry') : Args(1) {

+ my ( $self, $c, $id ) = @_;

+ $c->stash->{entry} = $c->model('KiokuDB')->lookup($id);

+}

+

+1;

+```

+

+The function **view** fetch an entry from the kiokudb backend, and store it in the stash, so we can use it in our template.

+

+**root/src/entry/view.tt2**

+

+```html

+<h1><a href="[% entry.permalink %]">[% entry.title %]</a></h1>

+<span>Posted [% entry.date %] by [% entry.author %]</span>

+<div id="content">

+ [% entry.content %]

+</div>

+```

+

+If you point your browser to an entry (something like **http://localhost:3000/entry/somesha256value**), you will see an entry:

+

+<img src='/imgs/show_entry.webp' alt='show entry'>

+

+Et voila, we are done with a really basic feed reader. You can add methods to add or delete feed, mark an entry as read, ...

+

+[The code is available on my git server](http://git.lumberjaph.net/p5-ironman-myfeedreader.git/).