=head1 SYNOPSIS
package Library::Schema;
- use base qw/DBIx::Class::Schema/;
+ use base qw/DBIx::Class::Schema/;
+
+ our $VERSION = 0.001;
+
# load Library::Schema::CD, Library::Schema::Book, Library::Schema::DVD
__PACKAGE__->load_classes(qw/CD Book DVD/);
- __PACKAGE__->load_components(qw/+DBIx::Class::Schema::Versioned/);
+ __PACKAGE__->load_components(qw/Schema::Versioned/);
__PACKAGE__->upgrade_directory('/path/to/upgrades/');
- __PACKAGE__->backup_directory('/path/to/backups/');
=head1 DESCRIPTION
-This module is a component designed to extend L<DBIx::Class::Schema>
-classes, to enable them to upgrade to newer schema layouts. To use this
-module, you need to have called C<create_ddl_dir> on your Schema to
-create your upgrade files to include with your delivery.
+This module provides methods to apply DDL changes to your database using SQL
+diff files. Normally these diff files would be created using
+L<DBIx::Class::Schema/create_ddl_dir>.
A table called I<dbix_class_schema_versions> is created and maintained by the
-module. This contains two fields, 'Version' and 'Installed', which
-contain each VERSION of your Schema, and the date+time it was installed.
-
-The actual upgrade is called manually by calling C<upgrade> on your
-schema object. Code is run at connect time to determine whether an
-upgrade is needed, if so, a warning "Versions out of sync" is
-produced.
+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.
-So you'll probably want to write a script which generates your DDLs and diffs
-and another which executes the upgrade.
+The upgrade is initiated manually by calling C<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 I<upgrade_directory>. If a suitable diff is
+not found then no upgrade is possible.
NB: At the moment, only SQLite and MySQL are supported. This is due to
spotty behaviour in the SQL::Translator producers, please help us by
-them.
-
+enhancing them. Ask on the mailing list or IRC channel for details (details
+in L<DBIx::Class>).
=head1 GETTING STARTED
+Firstly you need to setup your schema class as per the L</SYNOPSIS>, make sure
+you have specified an upgrade_directory and an initial $VERSION.
-=cut
+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:
-=head1 METHODS
+ use strict;
+ use Pod::Usage;
+ use Getopt::Long;
+ use MyApp::Schema;
-=head2 upgrade_directory
+ my ( $preversion, $help );
+ GetOptions(
+ 'p|preversion:s' => \$preversion,
+ ) or die pod2usage;
-Use this to set the directory your upgrade files are stored in.
+ 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 );
-=head2 backup_directory
+Then your upgrade script might look like so:
+
+ use strict;
+ use MyApp::Schema;
+
+ my $schema = MyApp::Schema->connect(
+ $dsn,
+ $user,
+ $password,
+ );
-Use this to set the directory you want your backups stored in.
+ if (!$schema->get_db_version()) {
+ # schema is unversioned
+ $schema->deploy();
+ } else {
+ $schema->upgrade();
+ }
+
+The script above assumes that if the database is unversioned then it is empty
+and we can safely deploy the DDL to it. However things are not always so simple.
+
+if you want to initialise a pre-existing database where the DDL is not the same
+as the DDL for your current schema version then you will need a diff which
+converts the database's DDL to the current DDL. The best way to do this is
+to get a dump of the database schema (without data) and save that in your
+SQL directory as version 0.000 (the filename must be as with
+L<DBIx::Class::Schema/ddl_filename>) then create a diff using your create DDL
+script given above from version 0.000 to the current version. Then hand check
+and if necessary edit the resulting diff to ensure that it will apply. Once you have
+done all that you can do this:
+
+ if (!$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.
=cut
__PACKAGE__->mk_classdata('do_backup');
__PACKAGE__->mk_classdata('do_diff_on_init');
+
+=head1 METHODS
+
+=head2 upgrade_directory
+
+Use this to set the directory your upgrade files are stored in.
+
+=head2 backup_directory
+
+Use this to set the directory you want your backups stored in (note that backups
+are disabled by default).
+
+=cut
+
=head2 install
=over 4
# default to current version if none passed
$new_version ||= $self->schema_version();
- unless ($new_version) {
+ if ($new_version) {
# create versions table and version row
$self->{vschema}->deploy;
$self->_set_db_version;
}
}
+=head2 deploy
+
+Same as L<DBIx::Class::Schema/deploy> but also calls C<install>.
+
+=cut
+
+sub deploy {
+ my $self = shift;
+ $self->next::method(@_);
+ $self->install();
+}
+
=head2 upgrade
Call this to attempt to upgrade your database from the version it is at to the version
-this DBIC schema is at.
+this DBIC schema is at. If they are the same it does nothing.
+
+It requires an SQL diff file to exist in you I<upgrade_directory>, normally you will
+have created this using L<DBIx::Class::Schema/create_ddl_dir>.
-It requires an SQL diff file to exist in $schema->upgrade_directory, normally you will
-have created this using $schema->create_ddl_dir.
+If successful the dbix_class_schema_versions table is updated with the current
+DBIC schema version.
=cut
Runs a set of SQL statements matching a passed in regular expression. The
idea is that this method can be called any number of times from your
-C<upgrade> method, running whichever commands you specify via the
+C<do_upgrade> method, running whichever commands you specify via the
regex in the parameter. Probably won't work unless called from the overridable
do_upgrade method.
=head2 get_db_version
Returns the version that your database is currently at. This is determined by the values in the
-dbix_class_schema_versions table that $self->upgrade writes to.
+dbix_class_schema_versions table that C<upgrade> and C<install> write to.
=cut
compatibility between the old versions table (SchemaVersions) and the new one
(dbix_class_schema_versions).
-To avoid the checks on connect, set the env var DBIC_NO_VERSION_CHECK or alternatively you can set the ignore_version attr in the forth arg like so:
+To avoid the checks on connect, set the env var DBIC_NO_VERSION_CHECK or alternatively you can set the ignore_version attr in the forth argument like so:
my $schema = MyApp::Schema->connect(
$dsn,
projects / dbsrgits/DBIx-Class.git / commitdiff