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Mojo::Pg::Migrations

Section: User Contributed Perl Documentation (3)
Updated: 2019-01-21
Index

NAME

Mojo::Pg::Migrations - Migrations

SYNOPSIS

  use Mojo::Pg::Migrations;  my $migrations = Mojo::Pg::Migrations->new(pg => $pg);  $migrations->from_file('/home/sri/migrations.sql')->migrate;

DESCRIPTION

Mojo::Pg::Migrations is used by Mojo::Pg to allow database schemas toevolve easily over time. A migration file is just a collection of sql blocks,with one or more statements, separated by comments of the form"-- VERSION UP/DOWN".

  -- 1 up  create table messages (message text);  insert into messages values ('I ♥ Mojolicious!');  -- 1 down  drop table messages;  -- 2 up (...you can comment freely here...)  create table stuff (whatever int);  -- 2 down  drop table stuff;

The idea is to let you migrate from any version, to any version, up and down.Migrations are very safe, because they are performed in transactions and onlyone can be performed at a time. If a single statement fails, the wholemigration will fail and get rolled back. Every set of migrations has a``name'', which is stored together with the currently active version in anautomatically created table named "mojo_migrations".

ATTRIBUTES

Mojo::Pg::Migrations implements the following attributes.

name

  my $name    = $migrations->name;  $migrations = $migrations->name('foo');

Name for this set of migrations, defaults to "migrations".

pg

  my $pg      = $migrations->pg;  $migrations = $migrations->pg(Mojo::Pg->new);

Mojo::Pg object these migrations belong to. Note that this attribute isweakened.

METHODS

Mojo::Pg::Migrations inherits all methods from Mojo::Base and implementsthe following new ones.

active

  my $version = $migrations->active;

Currently active version.

from_data

  $migrations = $migrations->from_data;  $migrations = $migrations->from_data('main');  $migrations = $migrations->from_data('main', 'file_name');

Extract migrations from a file in the DATA section of a class with``data_section'' in Mojo::Loader, defaults to using the caller class and``name''.

  __DATA__  @@ migrations  -- 1 up  create table messages (message text);  insert into messages values ('I ♥ Mojolicious!');  -- 1 down  drop table messages;

from_file

  $migrations = $migrations->from_file('/home/sri/migrations.sql');

Extract migrations from a file.

from_string

  $migrations = $migrations->from_string(    '-- 1 up     create table foo (bar int);     -- 1 down     drop table foo;'  );

Extract migrations from string.

latest

  my $version = $migrations->latest;

Latest version available.

migrate

  $migrations = $migrations->migrate;  $migrations = $migrations->migrate(3);

Migrate from ``active'' to a different version, up or down, defaults to using``latest''. All version numbers need to be positive, with version 0representing an empty database.

  # Reset database  $migrations->migrate(0)->migrate;

sql_for

  my $sql = $migrations->sql_for(5, 10);

Get SQL to migrate from one version to another, up or down.

DEBUGGING

You can set the "MOJO_MIGRATIONS_DEBUG" environment variable to get someadvanced diagnostics information printed to "STDERR".

  MOJO_MIGRATIONS_DEBUG=1

METHODS

active
from_data
from_file
from_string
latest
migrate
sql_for

DEBUGGING

SEE ALSO

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