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+Following
+[[http://www.shadowcat.co.uk/blog/matt-s-trout/iron-man/][Matt's post]]
+about people not blogging enough about Perl, I've decided to try to post
+once a week about Perl. So I will start by a series of articles about
+what we call *modern Perl*. For this, I will write a simple feed
+agregator (using [[https://metacpan.org/pod/Moose][Moose]],
+[[http://search.cpan.org/perldoc?DBIx::Class][DBIx::Class]],
+[[http://search.cpan.org/perldoc?KiokuDB][KiokuDB]], some tests, and a
+basic frontend (with
+[[http://search.cpan.org/perldoc?Catalyst][Catalyst]]). This article
+will be split in four parts:
+
+-  the first one will explain how to create a schema using *DBIx::Class*
+-  the second will be about the aggregator. I will use *Moose** and
+   *KiokuDB*
+-  the third one will be about writing tests with *Test::Class*
+-  the last one will focus on *Catalyst*
+
+The code of these modules will be available on
+[[http://git.lumberjaph.net/][my git server]] at the same time each
+article is published.
+
+#+BEGIN_QUOTE
+  I'm not showing you how to write the perfect feed aggregator. The
+  purpose of this series of articles is only to show you how to write a
+  simple aggregator using modern Perl.
+#+END_QUOTE
+
+*** The database schema
+
+We will use a database to store a list of feeds and feed entries. As I
+don't like, no, wait, I /hate/ SQL, I will use an ORM for accessing the
+database. For this, my choice is *DBIx::Class*, the best ORM available
+in Perl.
+
+#+BEGIN_QUOTE
+  If you never have used an ORM before, ORM stands for Object Relational
+  Mapping. It's a SQL to OO mapper that creates an abstract
+  encapsulation of your databases operations. *DBIx::Class*' purpose is
+  to represent "queries in your code as perl-ish as possible.
+#+END_QUOTE
+
+For a basic aggregator we need:
+
+-  a table for the list of feeds
+-  a table for the entries
+
+We will create these two tables using /DBIx::Class/. For this, we first
+create a Schema module. I use /Module::Setup/, but you can use
+*Module::Starter* or whatever you want.
+
+#+BEGIN_EXAMPLE
+    % module-setup MyModel
+    % cd MyModel
+    % vim lib/MyModel.pm
+#+END_EXAMPLE
+
+#+BEGIN_SRC perl
+    package MyModel;
+    use base qw/DBIx::Class::Schema/;
+    __PACKAGE__->load_classes();
+    1;
+#+END_SRC
+
+So, we have just created a schema class. The *load\_classes* method
+loads all the classes that reside under the *MyModel* namespace. We now
+create the result class *MyModel::Feed* in *lib/MyModel/Feed.pm*:
+
+#+BEGIN_SRC perl
+    package MyModel::Feed;
+    use base qw/DBIx::Class/;
+    __PACKAGE__->load_components(qw/Core/);
+    __PACKAGE__->table('feed');
+    __PACKAGE__->add_columns(qw/ feedid url /);
+    __PACKAGE__->set_primary_key('feedid');
+    __PACKAGE__->has_many(entries => 'MyModel::Entry', 'feedid');
+    1;
+#+END_SRC
+
+Pretty self explanatory: we declare a result class that uses the table
+feed, with two columns: *feedid* and *url*, *feedid* being the primary
+key. The *has\_many* method declares a one-to-many relationship.
+
+Now the result class *MyModel::Entry* in *lib/MyModel/Entry.pm*:
+
+#+BEGIN_SRC perl
+    package MyModel::Entry;
+    use base qw/DBIx::Class/;
+    __PACKAGE__->load_components(qw/Core/);
+    __PACKAGE__->table('entry');
+    __PACKAGE__->add_columns(qw/ entryid permalink feedid/);
+    __PACKAGE__->set_primary_key('entryid');
+    __PACKAGE__->belongs_to(feed => 'MyModel::Feed', 'feedid');
+    1;
+#+END_SRC
+
+Here we declare *feed* as a foreign key, using the column name *feedid*.
+
+You can do a more complex declaration of your schema. Let's say you want
+to declare the type of your fields, you can do this:
+
+#+BEGIN_SRC perl
+    __PACKAGE__->add_columns(
+        'permalink' => {
+            'data_type'         => 'TEXT',
+            'is_auto_increment' => 0,
+            'default_value'     => undef,
+            'is_foreign_key'    => 0,
+            'name'              => 'url',
+            'is_nullable'       => 1,
+            'size'              => '65535'
+        },
+    );
+#+END_SRC
+
+*DBIx::Class* also provides hooks for the deploy command. If you are
+using MySQL, you may need a InnoDB table. In your class, you can add
+this:
+
+#+BEGIN_SRC perl
+    sub sqlt_deploy_hook {
+        my ($self, $sqlt_table) = @_;
+        $sqlt_table->extra(
+            mysql_table_type => 'InnoDB',
+            mysql_charset    => 'utf8'
+        );
+    }
+#+END_SRC
+
+Next time you call deploy on this table, the hook will be sent to
+*SQL::Translator::Schema*, and force the type of your table to InnoDB,
+and the charset to utf8.
+
+Now that we have a *DBIx::Class* schema, we need to deploy it. For this,
+I always do the same thing: create a *bin/deploy\_mymodel.pl* script
+with the following code:
+
+#+BEGIN_SRC perl
+    use strict;
+    use feature 'say';
+    use Getopt::Long;
+    use lib('lib');
+    use MyModel;
+
+    GetOptions(
+        'dsn=s'    => \my $dsn,
+        'user=s'   => \my $user,
+        'passwd=s' => \my $passwd
+    ) or die usage();
+
+    my $schema = MyModel->connect($dsn, $user, $passwd);
+    say 'deploying schema ...';
+    $schema->deploy;
+
+    say 'done';
+
+    sub usage {
+        say
+            'usage: deploy_mymodel.pl --dsn $dsn --user $user --passwd $passwd';
+    }
+#+END_SRC
+
+This script will deploy for you the schema (you need to create the
+database first if using with mysql).
+
+Executing the following command
+=perl bin/deploy_mymodel.pl --dsn dbi:SQLite:model.db= will generate a
+*model.db* database so we can work and test it. Now that we got our
+(really) simple *MyModel* schema, we can start to hack on our
+aggregator.
+
+[[http://git.lumberjaph.net/p5-ironman-mymodel.git/][The code is
+available on my git server]].
+
+#+BEGIN_QUOTE
+  while using *DBIx::Class*, you may want to take a look at the
+  generated queries. For this, export =DBIC_TRACE=1= in your
+  environment, and the queries will be printed on STDERR.
+#+END_QUOTE