| DBIx::Class::Manual::Example - Simple CD database example |
DBIx::Class::Manual::Example - Simple CD database example
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
Install DBIx::Class via CPAN should be sufficient.
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
Change directory back from db to the directory app:
cd ../
Now create some more directories:
mkdir MyDatabase mkdir MyDatabase/Main
Then, create the following DBIx::Class::Schema classes:
MyDatabase/Main.pm:
package MyDatabase::Main; use base qw/DBIx::Class::Schema/; __PACKAGE__->load_classes(qw/Artist Cd Track/);
1;
MyDatabase/Main/Artist.pm:
package MyDatabase::Main::Artist;
use base qw/DBIx::Class/;
__PACKAGE__->load_components(qw/PK::Auto Core/);
__PACKAGE__->table('artist');
__PACKAGE__->add_columns(qw/ artistid name /);
__PACKAGE__->set_primary_key('artistid');
__PACKAGE__->has_many('cds' => 'MyDatabase::Main::Cd');
1;
MyDatabase/Main/Cd.pm:
package MyDatabase::Main::Cd;
use base qw/DBIx::Class/;
__PACKAGE__->load_components(qw/PK::Auto Core/);
__PACKAGE__->table('cd');
__PACKAGE__->add_columns(qw/ cdid artist title/);
__PACKAGE__->set_primary_key('cdid');
__PACKAGE__->belongs_to('artist' => 'MyDatabase::Main::Artist');
__PACKAGE__->has_many('tracks' => 'MyDatabase::Main::Track');
1;
MyDatabase/Main/Track.pm:
package MyDatabase::Main::Track;
use base qw/DBIx::Class/;
__PACKAGE__->load_components(qw/PK::Auto Core/);
__PACKAGE__->table('track');
__PACKAGE__->add_columns(qw/ trackid cd title/);
__PACKAGE__->set_primary_key('trackid');
__PACKAGE__->belongs_to('cd' => 'MyDatabase::Main::Cd');
1;
insertdb.pl
#!/usr/bin/perl -w
use MyDatabase::Main; use strict;
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')->search({
name => $albums{$lp}
});
push @cds, [$lp, $artist->first];
}
$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')->search({
title => $tracks{$track},
});
push @tracks, [$cdname->first, $track];
}
$schema->populate('Track',[
[qw/cd title/],
@tracks,
]);
testdb.pl:
#!/usr/bin/perl -w
use MyDatabase::Main; use strict;
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):\n";
my $rs = $schema->resultset('Track')->search(
{
'cd.title' => $cdtitle
},
{
join => [qw/ cd /],
prefetch => [qw/ cd /]
}
);
while (my $track = $rs->next) {
print $track->title . "\n";
}
print "\n";
}
sub get_tracks_by_artist {
my $artistname = shift;
print "get_tracks_by_artist($artistname):\n";
my $rs = $schema->resultset('Track')->search(
{
'artist.name' => $artistname
},
{
join => {
'cd' => 'artist'
},
}
);
while (my $track = $rs->next) {
print $track->title . "\n";
}
print "\n";
}
sub get_cd_by_track {
my $tracktitle = shift;
print "get_cd_by_track($tracktitle):\n";
my $rs = $schema->resultset('Cd')->search(
{
'tracks.title' => $tracktitle
},
{
join => [qw/ tracks /],
}
);
my $cd = $rs->first;
print $cd->title . "\n\n";
}
sub get_cds_by_artist {
my $artistname = shift;
print "get_cds_by_artist($artistname):\n";
my $rs = $schema->resultset('Cd')->search(
{
'artist.name' => $artistname
},
{
join => [qw/ artist /],
prefetch => [qw/ artist /]
}
);
while (my $cd = $rs->next) {
print $cd->title . "\n";
}
print "\n";
}
sub get_artist_by_track {
my $tracktitle = shift;
print "get_artist_by_track($tracktitle):\n";
my $rs = $schema->resultset('Artist')->search(
{
'tracks.title' => $tracktitle
},
{
join => {
'cds' => 'tracks'
}
}
);
my $artist = $rs->first;
print $artist->name . "\n\n";
}
sub get_artist_by_cd {
my $cdtitle = shift;
print "get_artist_by_cd($cdtitle):\n";
my $rs = $schema->resultset('Artist')->search(
{
'cds.title' => $cdtitle
},
{
join => [qw/ cds /],
}
);
my $artist = $rs->first;
print $artist->name . "\n\n";
}
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
A reference implentation 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.
sc_ from irc.perl.org#dbix-class Kieren Diment <kd@totaldatasolution.com>
| DBIx::Class::Manual::Example - Simple CD database example |