NAME

       Mojo::SQLite::Migrations - Migrations

SYNOPSIS

         use Mojo::SQLite::Migrations;

         my $migrations = Mojo::SQLite::Migrations->new(sqlite => $sql);
         $migrations->from_file('/home/dbook/migrations.sql')->migrate;

DESCRIPTION

       Mojo::SQLite::Migrations is used by Mojo::SQLite to allow database schemas to evolve
       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 X Mojolicious!');
         -- 1 down
         drop table messages;

         -- 2 up (...you can comment freely here...)
         create table stuff (whatever integer);
         -- 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 only one can be performed at
       a time. If a single statement fails, the whole migration will fail and get rolled back.
       Every set of migrations has a "name", which is stored together with the currently active
       version in an automatically created table named "mojo_migrations".

ATTRIBUTES

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

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

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

   sqlite
         my $sql     = $migrations->sqlite;
         $migrations = $migrations->sqlite(Mojo::SQLite->new);

       Mojo::SQLite object these migrations belong to. Note that this attribute is weakened.

METHODS

       Mojo::SQLite::Migrations inherits all methods from Mojo::Base and implements the 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 X Mojolicious!');
         -- 1 down
         drop table messages;

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

       Extract migrations from a file.

   from_string
         $migrations = $migrations->from_string(
           '-- 1 up
            create table foo (bar integer);
            -- 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 0 representing 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 some advanced
       diagnostics information printed to "STDERR".

         MOJO_MIGRATIONS_DEBUG=1

BUGS

       Report any issues on the public bugtracker.

AUTHOR

       Dan Book, "dbook@cpan.org"

COPYRIGHT AND LICENSE

       Copyright 2015, Dan Book.

       This library is free software; you may redistribute it and/or modify it under the terms of
       the Artistic License version 2.0.

SEE ALSO

       Mojo::SQLite