DBIx::Class::Manual::Example(3) 			User Contributed Perl Documentation			   DBIx::Class::Manual::Example(3)

NAME

       DBIx::Class::Manual::Example - Simple CD database example

DESCRIPTION

       This tutorial will guide you through the process of setting up and testing a very basic CD database using SQLite, with DBIx::Class::Schema
       as the database frontend.

       The database consists of the following:

	 table 'artist' with columns:  artistid, name
	 table 'cd'	with columns:  cdid, artist, title
	 table 'track'	with columns:  trackid, cd, title

       And these rules exists:

	 one artist can have many cds
	 one cd belongs to one artist
	 one cd can have many tracks
	 one track belongs to one cd

   Installation
       Install DBIx::Class via CPAN should be sufficient.

       Create the database/tables

       First make and change the directory:

	 mkdir app
	 cd app
	 mkdir db
	 cd db

       This example uses SQLite which is a dependency of DBIx::Class, so you shouldn't have to install extra software.

       Save the following into a example.sql in the directory db

	 CREATE TABLE artist (
	   artistid INTEGER PRIMARY KEY,
	   name TEXT NOT NULL
	 );

	 CREATE TABLE cd (
	   cdid INTEGER PRIMARY KEY,
	   artist INTEGER NOT NULL REFERENCES artist(artistid),
	   title TEXT NOT NULL
	 );

	 CREATE TABLE track (
	   trackid INTEGER PRIMARY KEY,
	   cd INTEGER NOT NULL REFERENCES cd(cdid),
	   title TEXT NOT NULL
	 );

       and create the SQLite database file:

	 sqlite3 example.db < example.sql

       Set up DBIx::Class::Schema

       Change directory back from db to the directory app:

	 cd ../

       Now create some more directories:

	 mkdir MyDatabase
	 mkdir MyDatabase/Main
	 mkdir MyDatabase/Main/Result
	 mkdir MyDatabase/Main/ResultSet

       Then, create the following DBIx::Class::Schema classes:

       MyDatabase/Main.pm:

	 package MyDatabase::Main;
	 use base qw/DBIx::Class::Schema/;
	 __PACKAGE__->load_namespaces;

	 1;

       MyDatabase/Main/Result/Artist.pm:

	 package MyDatabase::Main::Result::Artist;
	 use base qw/DBIx::Class::Core/;
	 __PACKAGE__->table('artist');
	 __PACKAGE__->add_columns(qw/ artistid name /);
	 __PACKAGE__->set_primary_key('artistid');
	 __PACKAGE__->has_many('cds' => 'MyDatabase::Main::Result::Cd');

	 1;

       MyDatabase/Main/Result/Cd.pm:

	 package MyDatabase::Main::Result::Cd;
	 use base qw/DBIx::Class::Core/;
	 __PACKAGE__->load_components(qw/InflateColumn::DateTime/);
	 __PACKAGE__->table('cd');
	 __PACKAGE__->add_columns(qw/ cdid artist title/);
	 __PACKAGE__->set_primary_key('cdid');
	 __PACKAGE__->belongs_to('artist' => 'MyDatabase::Main::Result::Artist');
	 __PACKAGE__->has_many('tracks' => 'MyDatabase::Main::Result::Track');

	 1;

       MyDatabase/Main/Result/Track.pm:

	 package MyDatabase::Main::Result::Track;
	 use base qw/DBIx::Class::Core/;
	 __PACKAGE__->table('track');
	 __PACKAGE__->add_columns(qw/ trackid cd title /);
	 __PACKAGE__->set_primary_key('trackid');
	 __PACKAGE__->belongs_to('cd' => 'MyDatabase::Main::Result::Cd');

	 1;

       Write a script to insert some records

       insertdb.pl

	 #!/usr/bin/perl

	 use strict;
	 use warnings;

	 use MyDatabase::Main;

	 my $schema = MyDatabase::Main->connect('dbi:SQLite:db/example.db');

	 #  here's some of the SQL that is going to be generated by the schema
	 #  INSERT INTO artist VALUES (NULL,'Michael Jackson');
	 #  INSERT INTO artist VALUES (NULL,'Eminem');

	 my @artists = (['Michael Jackson'], ['Eminem']);
	 $schema->populate('Artist', [
	    [qw/name/],
	    @artists,
	 ]);

	 my %albums = (
	   'Thriller' => 'Michael Jackson',
	   'Bad' => 'Michael Jackson',
	   'The Marshall Mathers LP' => 'Eminem',
	 );

	 my @cds;
	 foreach my $lp (keys %albums) {
	   my $artist = $schema->resultset('Artist')->find({
	     name => $albums{$lp}
	   });
	   push @cds, [$lp, $artist->id];
	 }

	 $schema->populate('Cd', [
	   [qw/title artist/],
	   @cds,
	 ]);

	 my %tracks = (
	   'Beat It'	     => 'Thriller',
	   'Billie Jean'     => 'Thriller',
	   'Dirty Diana'     => 'Bad',
	   'Smooth Criminal' => 'Bad',
	   'Leave Me Alone'  => 'Bad',
	   'Stan'	     => 'The Marshall Mathers LP',
	   'The Way I Am'    => 'The Marshall Mathers LP',
	 );

	 my @tracks;
	 foreach my $track (keys %tracks) {
	   my $cdname = $schema->resultset('Cd')->find({
	     title => $tracks{$track},
	   });
	   push @tracks, [$cdname->id, $track];
	 }

	 $schema->populate('Track',[
	   [qw/cd title/],
	   @tracks,
	 ]);

       Create and run the test scripts

       testdb.pl:

	 #!/usr/bin/perl

	 use strict;
	 use warnings;

	 use MyDatabase::Main;

	 my $schema = MyDatabase::Main->connect('dbi:SQLite:db/example.db');
	 # for other DSNs, e.g. MySQL, see the perldoc for the relevant dbd
	 # driver, e.g perldoc L<DBD::mysql>.

	 get_tracks_by_cd('Bad');
	 get_tracks_by_artist('Michael Jackson');

	 get_cd_by_track('Stan');
	 get_cds_by_artist('Michael Jackson');

	 get_artist_by_track('Dirty Diana');
	 get_artist_by_cd('The Marshall Mathers LP');

	 sub get_tracks_by_cd {
	   my $cdtitle = shift;
	   print "get_tracks_by_cd($cdtitle):
";
	   my $rs = $schema->resultset('Track')->search(
	     {
	       'cd.title' => $cdtitle
	     },
	     {
	       join	=> [qw/ cd /],
	     }
	   );
	   while (my $track = $rs->next) {
	     print $track->title . "
";
	   }
	   print "
";
	 }

	 sub get_tracks_by_artist {
	   my $artistname = shift;
	   print "get_tracks_by_artist($artistname):
";
	   my $rs = $schema->resultset('Track')->search(
	     {
	       'artist.name' => $artistname
	     },
	     {
	       join => {
		 'cd' => 'artist'
	       },
	     }
	   );
	   while (my $track = $rs->next) {
	     print $track->title . "
";
	   }
	   print "
";
	 }

	 sub get_cd_by_track {
	   my $tracktitle = shift;
	   print "get_cd_by_track($tracktitle):
";
	   my $rs = $schema->resultset('Cd')->search(
	     {
	       'tracks.title' => $tracktitle
	     },
	     {
	       join	=> [qw/ tracks /],
	     }
	   );
	   my $cd = $rs->first;
	   print $cd->title . "

";
	 }

	 sub get_cds_by_artist {
	   my $artistname = shift;
	   print "get_cds_by_artist($artistname):
";
	   my $rs = $schema->resultset('Cd')->search(
	     {
	       'artist.name' => $artistname
	     },
	     {
	       join	=> [qw/ artist /],
	     }
	   );
	   while (my $cd = $rs->next) {
	     print $cd->title . "
";
	   }
	   print "
";
	 }

	 sub get_artist_by_track {
	   my $tracktitle = shift;
	   print "get_artist_by_track($tracktitle):
";
	   my $rs = $schema->resultset('Artist')->search(
	     {
	       'tracks.title' => $tracktitle
	     },
	     {
	       join => {
		 'cds' => 'tracks'
	       }
	     }
	   );
	   my $artist = $rs->first;
	   print $artist->name . "

";
	 }

	 sub get_artist_by_cd {
	   my $cdtitle = shift;
	   print "get_artist_by_cd($cdtitle):
";
	   my $rs = $schema->resultset('Artist')->search(
	     {
	       'cds.title' => $cdtitle
	     },
	     {
	       join	=> [qw/ cds /],
	     }
	   );
	   my $artist = $rs->first;
	   print $artist->name . "

";
	 }

       It should output:

	 get_tracks_by_cd(Bad):
	 Dirty Diana
	 Smooth Criminal
	 Leave Me Alone

	 get_tracks_by_artist(Michael Jackson):
	 Beat it
	 Billie Jean
	 Dirty Diana
	 Smooth Criminal
	 Leave Me Alone

	 get_cd_by_track(Stan):
	 The Marshall Mathers LP

	 get_cds_by_artist(Michael Jackson):
	 Thriller
	 Bad

	 get_artist_by_track(Dirty Diana):
	 Michael Jackson

	 get_artist_by_cd(The Marshall Mathers LP):
	 Eminem

Notes
       A reference implementation of the database and scripts in this example are available in the main distribution for DBIx::Class under the
       directory t/examples/Schema.

       With these scripts we're relying on @INC looking in the current working directory.  You may want to add the MyDatabase namespaces to @INC
       in a different way when it comes to deployment.

       The testdb.pl script is an excellent start for testing your database model.

       This example uses "load_namespaces" in DBIx::Class::Schema to load in the appropriate Row classes from the MyDatabase::Main::Result
       namespace, and any required resultset classes from the MyDatabase::Main::ResultSet namespace (although we created the directory in the
       directions above we did not add, or need to add, any resultset classes).

TODO

AUTHOR

	 sc_ from irc.perl.org#dbix-class
	 Kieren Diment <kd@totaldatasolution.com>
	 Nigel Metheringham <nigelm@cpan.org>

perl v5.16.2							    2012-08-16					   DBIx::Class::Manual::Example(3)