=pod

=for advent_year 2009

=for advent_day 17

=for advent_title  Merry DBIx::Class!

=for advent_author Yanick Champoux


Gluggag&aelig;gir, P<2008-12-13|let us recall>, is an IT elf who moved into Q&A
after last season, a decision that right now make him very sad. You see,
the project he's been put on is P<2008-12-5|Santa's ChildrenDB application>
which&mdash;I'm ashamed to report&mdash;has gotten quite bad.

For one the application's interface to the database is a mess.
An ugly quagmire, a pathetic excuse of an API. Its guts are bloated,
convoluted and impossible to read. Truly the type of coding horror that
makes baby seals cry.

Worse still, it runs on a costly database system mandated by the hefty load
of the app in production. But did Glugg get a second copy for testing?
Of course not! Marketing gets leather chairs and unicorn barbeques,
but he's stuck working on a popcorn string budget.

But wait! Glugg remembered that North Pole Mongers presentation about all
things M<DBIx::Class>. Inspired, he plopped on his chair and began to type
real fast:

=begin code

use DBIx::Class::Schema::Loader qw/ make_schema_at /;

make_schema_at(
    'ChildrenDB::Schema',
    { debug => 1, dump_directory => './lib' },
    [ 'dbi:HoHoHoracle:ChildrenDB,'santa','c00k13s' ],
);

=end code

Et voil&agrave;! In a flash he has generated Dozens of modules&mdash;one for each
table. Blissfully, he can now play with the database using code that would
be simple, sweet and palatable.

But an interface, as splendid as it might be, is all but useless if there is
no database to connect to. So Glugg decided to create a duplicate testing db,
which brings us to script number two:

=begin code

use lib qw/ lib /;
use ChildrenDB::Schema;

my $schema = ChildrenDB::Schema->connect( 
                'dbi:SQLite:dbname=childrendb.sqlite' );

$schema->deploy;

=end code
    
Huzzah! Glugg was now the proud owner of a clone of ChildrenDB. One that
would run as long as the slope isn't too steep. Still 'twas better than
nothing (and almost as cheap).

Already a fairly happy hacker since his mission was no longer doomed to
be a flop, inspiration struck again and he saw how to add a cherry on top:

=begin code

use lib qw/ lib /;
use ChildrenDB::Schema;
use SQL::Translator;

my $schema = ChildrenDB::Schema->connect( 
    'dbi:SQLite:dbname=childrendb.sqlite',
);

SQL::Translator->new(
    parser => 'SQL::Translator::Parser::DBIx::Class',
    parser_args => { package => $schema },

    to => 'GraphViz',
    producer_args => { out_file => 'childrendb.png' },
)->translate;

=end code

With those lines was produced a nice diagram of all the db's tables and keys.
A true treasure map, a gold mine of insight that would save Glugg from many a
pitfall!

This is where our story reaches its happy ending.
Glugg still has work to do, but for now we'll leave it at that.
Let's just give three cheers to the li'l elf who built an API,
a database and a diagram in five minutes flat!

=cut