Phpmig

What is it?

Phpmig is a (database) migration tool for php, that should be adaptable for use with most PHP 5.3+ projects. It's kind of like doctrine migrations, without the doctrine. Although you can use doctrine if you want. And ironically, I use doctrine in my examples.

How does it work?

$ phpmig migrate

Phpmig aims to be vendor/framework independent, and in doing so, requires you to do a little bit of work up front to use it.

Phpmig requires a bootstrap file, that must return an object that implements the ArrayAccess interface with several predefined keys. We recommend returning an instance of Pimple, a simple dependency injection container (there's a version bundled at \Phpmig\Pimple\Pimple). This is also an ideal opportunity to expose your own services to the migrations themselves, which have access to the container.

Getting Started

The best way to install phpmig is using pear

$ sudo pear channel-discover pear.atstsolutions.co.uk
$ sudo pear install atst/phpmig-alpha

Alternatively to pull phpmig from github

$ git clone https://github.com/davedevelopment/phpmig.git phpmig
$ cd phpmig
$ git submodule init
$ git submodule update

Phpmig can do a little configuring for you to get started, go to the root of your project and:

$ phpmig init
+d ./migrations Place your migration files in here
+f ./phpmig.php Create services in here
$ 

It can generate migrations, but you have to tell it where. Phpmig gets you to supply it with a list of migrations, so it doesn't know where to put them. Migration files should be named versionnumber_name.php, where version number is made up of 0-9 and name is CamelCase or snake_case. Each migration file should contain a class with the same name as the file in CamelCase.

$ phpmig generate AddRatingToLolCats ./migrations
+f ./migrations/20111018171411_AddRatingToLolCats.php
$ phpmig status

 Status   Migration ID    Migration Name 
-----------------------------------------
   down  20111018171929  AddRatingToLolCats

Use the migrate command to run migrations

$ phpmig migrate
 == 20111018171411 AddRatingToLolCats migrating
 == 20111018171411 AddRatingToLolCats migrated 0.0005s
$ phpmig status

 Status   Migration ID    Migration Name 
-----------------------------------------
     up  20111018171929  AddRatingToLolCats

$

Better Persistence

The init command creates a bootstrap file that specifies a flat file to use to track which migrations have been run, which isn't great. You can use the provided adapters to store this information in your database. For example, to use Doctrine's DBAL:

<?php

# phpmig.php

// do some autoloading of Doctrine here

use \Phpmig\Adapter,
    \Phpmig\Pimple\Pimple,
    \Doctrine\DBAL\DriverManager;

$container = new Pimple();

$container['db'] = $container->share(function() {
    return DriverManager::getConnection(array(
        'driver' => 'pdo_sqlite',
        'path'   => __DIR__ . DIRECTORY_SEPARATOR . 'db.sqlite',
    ));
});

$container['phpmig.adapter'] = $container->share(function() use ($container) {
    return new Adapter\Doctrine\DBAL($container['db'], 'migrations');
});

$container['phpmig.migrations'] = function() {
    return glob(__DIR__ . DIRECTORY_SEPARATOR . 'migrations/*.php');
};

return $container;   

Unfortunately Zend Framework does not have a Database Abstraction Layer and setting up migrations requires couple additional steps. You first need to prepare the configuration. It might be in any format supported by Zend_Config. Here is an example in YAML for MySQL:

phpmig:
  tableName: migrations
  createStatement: CREATE TABLE migrations ( version INT(11) UNSIGNED NOT NULL );

In configuration file you need to provide the table name where the migrations will be stored and a create statement. You can use one of the configurations provided in the config folder for some common RDBMS.

Here is how the bootstrap file should look like:

<?php

# phpmig.php

// Set some constants
define('PHPMIG_PATH', realpath(dirname(__FILE__)));
define('VENDOR_PATH', PHPMIG_PATH . '/vendor');
set_include_path(get_include_path() . PATH_SEPARATOR . VENDOR_PATH);

// Register autoloading
require_once 'Zend/Loader/Autoloader.php';
$autoloader = Zend_Loader_Autoloader::getInstance();
$autoloader->registerNamespace('Zend_');

use \Phpmig\Pimple\Pimple,
    \Phpmig\Adapter\Zend\Db;

$container = new Pimple();

$container['db'] = $container->share(function() {
    return Zend_Db::factory('pdo_mysql', array(
        'dbname' => 'DBNAME',
        'username' => 'USERNAME',
        'password' => 'PASSWORD',
        'host' => 'localhost'
    ));
});

$container['phpmig.adapter'] = $container->share(function() use ($container) {
    $configuration = null;
    $configurationFile = PHPMIG_PATH . '/config/mysql.yaml';

    if (file_exists($configurationFile)) {
        $configuration = new Zend_Config_Yaml($configurationFile, null, array('ignore_constants' => true));
    }

    return new Db($container['db'], $configuration);
});

$container['phpmig.migrations'] = function() {
    return glob(__DIR__ . DIRECTORY_SEPARATOR . 'migrations/*.php');
};

return $container;

Writing Migrations

The migrations should extend the Phpmig\Migration\Migration class, and have access to the container. For example, assuming you've rewritten your bootstrap file like above:

<?php

use Phpmig\Migration\Migration;

class AddRatingToLolCats extends Migration
{
    /**
     * Do the migration
     */
    public function up()
    {
        $sql = "ALTER TABLE `lol_cats` ADD COLUMN `rating` INT(10) UNSIGNED NULL";
        $container = $this->getContainer(); 
        $container['db']->query($sql);
    }

    /**
     * Undo the migration
     */
    public function down()
    {
        $sql = "ALTER TABLE `lol_cats` DROP COLUMN `rating`";
        $container = $this->getContainer(); 
        $container['db']->query($sql);
    }
}

Rolling Back

You can roll back the last run migration by using the rollback command

$ phpmig rollback

To rollback all migration up to a specific migration you can specify the rollback target

$ phpmig rollback -t 20111101000144

or

$ phpmig rollback --target=20111101000144

By specifying 0 as the rollback target phpmig will revert all migrations

$ phpmig rollback -t 0

You can also rollback only a specific migration using the down command

$ phpmig down 20111101000144

Todo

• Some sort of migration manager, that will take some of the logic out of the commands for calculating which migrations have been run, which need running etc
• Adapters for Zend_Db and/or Zend_Db_Table and others?
• Redo and rollback commands
• Tests!
• Configuration?
• Someway of protecting against class definition clashes with regard to the symfony dependencies and the user supplied bootstrap?

Contributing

Feel free to fork and send me pull requests, but I don't have a 1.0 release yet, so I may change the API quite frequently. If you want to implement something that I might easily break, please drop me an email

Inspiration

I basically started copying ActiveRecord::Migrations in terms of the migration features, the bootstrapping was my own idea, the layout of the code was inspired by Symfony and Behat

Copyright

Pimple is copyright Fabien Potencier. Everything I haven't copied from anyone else is Copyright (c) 2011 Dave Marshall. See LICENCE for further details