NAME

SYNOPSIS

  package MyApp::Schema;
  use base qw/DBIx::Class::Schema/;

  our $VERSION = 0.001;

  # load MyApp::Schema::CD, MyApp::Schema::Book, MyApp::Schema::DVD
  __PACKAGE__->load_classes(qw/CD Book DVD/);

  __PACKAGE__->load_components(qw/Schema::Versioned/);
  __PACKAGE__->upgrade_directory('/path/to/upgrades/');

DESCRIPTION

A table called dbix_class_schema_versions is created and maintained by the module. This is used to determine which version your database is currently at. Similarly the $VERSION in your DBIC schema class is used to determine the current DBIC schema version.

The upgrade is initiated manually by calling "upgrade" on your schema object, this will attempt to upgrade the database from its current version to the current schema version using a diff from your upgrade_directory. If a suitable diff is not found then no upgrade is possible.

SEE ALSO

• Downgrades in addition to upgrades
• Multiple sql files per upgrade/downgrade/install
• Perl scripts allowed for upgrade/downgrade/install
• Just one set of files needed for upgrade, unlike this module where one might need to generate "factorial(scalar @versions)"

GETTING STARTED

Then you'll need two scripts, one to create DDL files and diffs and another to perform upgrades. Your creation script might look like a bit like this:

  use strict;
  use Pod::Usage;
  use Getopt::Long;
  use MyApp::Schema;

  my ( $preversion, $help );
  GetOptions(
    'p|preversion:s'  => \$preversion,
  ) or die pod2usage;

  my $schema = MyApp::Schema->connect(
    $dsn,
    $user,
    $password,
  );
  my $sql_dir = './sql';
  my $version = $schema->schema_version();
  $schema->create_ddl_dir( 'MySQL', $version, $sql_dir, $preversion );

Then your upgrade script might look like so:

  use strict;
  use MyApp::Schema;

  my $schema = MyApp::Schema->connect(
    $dsn,
    $user,
    $password,
  );

  if (!$schema->get_db_version()) {
    # schema is unversioned
    $schema->deploy();
  } else {
    $schema->upgrade();
  }

The script above assumes that if the database is unversioned then it is empty and we can safely deploy the DDL to it. However things are not always so simple.

if you want to initialise a pre-existing database where the DDL is not the same as the DDL for your current schema version then you will need a diff which converts the database's DDL to the current DDL. The best way to do this is to get a dump of the database schema (without data) and save that in your SQL directory as version 0.000 (the filename must be as with "ddl_filename" in DBIx::Class::Schema) then create a diff using your create DDL script given above from version 0.000 to the current version. Then hand check and if necessary edit the resulting diff to ensure that it will apply. Once you have done all that you can do this:

  if (!$schema->get_db_version()) {
    # schema is unversioned
    $schema->install("0.000");
  }

  # this will now apply the 0.000 to current version diff
  $schema->upgrade();

In the case of an unversioned database the above code will create the dbix_class_schema_versions table and write version 0.000 to it, then upgrade will then apply the diff we talked about creating in the previous paragraph and then you're good to go.

METHODS

 $self->run_upgrade(qr/create/i);

  my $schema = MyApp::Schema->connect(
    $dsn,
    $user,
    $password,
    { ignore_version => 1 },
  );

FURTHER QUESTIONS?

COPYRIGHT AND LICENSE