Ubuntu Manpage: DBIx::Class::DeploymentHandler::DeployMethod::SQL::Translator

Provided by: libdbix-class-deploymenthandler-perl_0.002233-2_all

NAME

       DBIx::Class::DeploymentHandler::DeployMethod::SQL::Translator - Manage your SQL and Perl migrations in
       nicely laid out directories

DESCRIPTION

       This class is the meat of DBIx::Class::DeploymentHandler.  It takes care of generating serialized
       schemata  as well as sql files to move from one version of a schema to the rest.  One of the hallmark
       features of this class is that it allows for multiple sql files for deploy and upgrade, allowing
       developers to fine tune deployment.  In addition it also allows for perl files to be run at any stage of
       the process.

       For basic usage see DBIx::Class::DeploymentHandler::HandlesDeploy.  What's documented here is extra fun
       stuff or private methods.

DIRECTORY LAYOUT

Arguably this is the best feature of DBIx::Class::DeploymentHandler. It's spiritually based upon
DBIx::Migration::Directories, but has a lot of extensions and modifications, so even if you are familiar
with it, please read this. I feel like the best way to describe the layout is with the following
example:

So basically, the code

$dm->deploy(1)

on an "SQLite" database that would simply run "$sql_migration_dir/SQLite/deploy/1/001-auto.sql". Next,

$dm->upgrade_single_step([1,2])

would run "$sql_migration_dir/SQLite/upgrade/1-2/001-auto.sql" followed by
"$sql_migration_dir/_common/upgrade/1-2/002-generate-customers.pl", and finally punctuated by
"$sql_migration_dir/_common/upgrade/_any/999-bump-action.pl".

".pl" files don't have to be in the "_common" directory, but most of the time they should be, because
perl scripts are generally database independent.

Note that unlike most steps in the process, "initialize" will not run SQL, as there may not even be an
database at initialize time. It will run perl scripts just like the other steps in the process, but
nothing is passed to them. Until people have used this more it will remain freeform, but a recommended
use of initialize is to have it prompt for username and password, and then call the appropriate "CREATE
DATABASE" commands etc.

Directory Specification
The following subdirectories are recognized by this DeployMethod:

"_source"
This directory can contain the following directories:

"deploy"
This directory merely contains directories named after schema versions, which in turn contain "yaml"
files that are serialized versions of the schema at that version. These files are not for editing by
hand.

"_preprocess_schema"
This directory can contain the following directories:

"downgrade"
This directory merely contains directories named after migrations, which are of the form
"$from_version-$to_version". Inside of these directories you may put Perl scripts which are to
return a subref that takes the arguments "$from_schema, $to_schema", which are
SQL::Translator::Schema objects.

"upgrade"
This directory merely contains directories named after migrations, which are of the form
"$from_version-$to_version". Inside of these directories you may put Perl scripts which are to
return a subref that takes the arguments "$from_schema, $to_schema", which are
SQL::Translator::Schema objects.

A typical usage of "_preprocess_schema" is to define indices or other non-DBIC type metadata. Here is
an example of how one might do that:

The following coderef could be placed in a file called _preprocess_schema/1-2/001-add-user-index.pl

sub {
my ($from, $to) = @_;

$to->get_table('Users')->add_index(
name => 'idx_Users_name',
fields => ['name'],
)
}

This would ensure that in version 2 of the schema the generated migrations include an index on
"Users.name". Frustratingly, due to the nature of SQL::Translator, you'll need to add this to each
migration or it will detect that it was left out and kindly remove the index for you.

An alternative to the above, which is likely to be a lot less annoying, is to define such data in your
schema directly, and only change it as you need to:

package MyApp::Schema::Result::User;

#[...]

sub sqlt_deploy_hook ( $self, $sqlt_table ) {
$sqlt_table->add_index(name => 'idx_Users_name', fields => [ 'name' ]);
}

$storage_type
This is a set of scripts that gets run depending on what your storage type is. If you are not sure
what your storage type is, take a look at the producers listed for SQL::Translator. Also note,
"_common" is a special case. "_common" will get merged into whatever other files you already have.
This directory can contain the following directories itself:

"initialize"
If you are using the "initialize" functionality, you should call initialize() before calling
"install". This has the same structure as the "deploy" subdirectory as well; that is, it has a
directory for each schema version. Unlike "deploy", "upgrade", and "downgrade" though, it can only
run ".pl" files, and the coderef in the perl files get no arguments passed to them.

"deploy"
Gets run when the schema is "deploy"ed. Structure is a directory per schema version, and then files
are merged with "_common" and run in filename order. ".sql" files are merely run, as expected.
".pl" files are run according to "PERL SCRIPTS".

"upgrade"
Gets run when the schema is "upgrade"d. Structure is a directory per upgrade step, (for example,
"1-2" for upgrading from version 1 to version 2,) and then files are merged with "_common" and run in
filename order. ".sql" files are merely run, as expected. ".pl" files are run according to "PERL
SCRIPTS".

"downgrade"
Gets run when the schema is "downgrade"d. Structure is a directory per downgrade step, (for example,
"2-1" for downgrading from version 2 to version 1,) and then files are merged with "_common" and run
in filename order. ".sql" files are merely run, as expected. ".pl" files are run according to "PERL
SCRIPTS".

Note that there can be an "_any" in the place of any of the versions (like "1-2" or 1), which means those
scripts will be run every time. So if you have an "_any" in "_common/upgrade", that script will get run
for every upgrade.

PERL SCRIPTS

       A perl script for this tool is very simple.  It merely needs to contain an anonymous  sub  that  takes  a
       DBIx::Class::Schema and the version set as it's arguments.

       A very basic perl script might look like:

        #!perl

        use strict;
        use warnings;

        use DBIx::Class::DeploymentHandler::DeployMethod::SQL::Translator::ScriptHelpers
           'schema_from_schema_loader';

        schema_from_schema_loader({ naming => 'v4' }, sub {
          my $schema = shift;

          # [1] for deploy, [1,2] for upgrade or downgrade, probably used with _any
          my $versions = shift;

          $schema->resultset('Users')->create({
            name => 'root',
            password => 'root',
          })
        })

       Note          that          the         above         uses         "schema_from_schema_loader"         in
       DBIx::Class::DeploymentHandler::DeployMethod::SQL::Translator::ScriptHelpers.  Using  a  raw  coderef  is
       strongly discouraged as it is likely to break as you modify your schema.

ATTRIBUTES

ignore_ddl
This attribute will, when set to true (default is false), cause the DM to use SQL::Translator to use the
"_source"'s serialized SQL::Translator::Schema instead of any pregenerated SQL. If you have a
development server this is probably the best plan of action as you will not be putting as many generated
files in your version control. Goes well with with "databases" of "[]".

force_overwrite
When this attribute is true generated files will be overwritten when the methods which create such files
are run again. The default is false, in which case the program will die with a message saying which file
needs to be deleted.

schema
The DBIx::Class::Schema (required) that is used to talk to the database and generate the DDL.

storage
The DBIx::Class::Storage that is actually used to talk to the database and generate the DDL. This is
automatically created with "_build_storage".

sql_translator_args
The arguments that get passed to SQL::Translator when it's used.

script_directory
The directory (default 'sql') that scripts are stored in

databases
The types of databases (default "[qw( MySQL SQLite PostgreSQL )]") to generate files for

txn_prep
This attribute will, when set to false (default is true), cause the DM to generate SQL without enclosing
"BEGIN" and "COMMIT" statements.

The (current) default behavior is to create DDLs wrapped in transactions and to remove anything that
looks like a transaction from the generated DDLs later when running the deployment.

Since this default behavior is error prone it is strictly recommended to set the "txn_prep" attribute to
false and remove all transaction statements from previously generated DDLs.

txn_wrap
Set to true (which is the default) to wrap all upgrades and deploys in a single transaction. This option
should be false if the DDL files contain transaction statements.

Keep in mind that not all DBMSes support transactions over DDL statements.

schema_version
The version the schema on your harddrive is at. Defaults to "$self->schema->schema_version".

version_source
The source name used to register the version storage with "schema". Defaults to "__VERSION".

AUTHOR

       Arthur Axel "fREW" Schmidt <frioux+cpan@gmail.com>

COPYRIGHT AND LICENSE

       This software is copyright (c) 2019 by Arthur Axel "fREW" Schmidt.

       This  is  free  software;  you  can  redistribute  it and/or modify it under the same terms as the Perl 5
       programming language system itself.

perl v5.36.0                                       2022-12-10              DBIx::Class::D...SQL::Translator(3pm)