A database migration utility for Codeigniter inspired by Ruby on Rails.


	Spicer Matthews <spicer@cloudmanic.com>
	Cloudmanic Labs, LLC

Based On:
	By: Mat'as Montes

	An open source utility for Codeigniter inspired by Ruby on Rails.

	The one thing Ruby on Rails has that Codeigniter does not have built in
	is database migrations. That function to keep track of database chages (versions)
	and migrate your database to what ever version you need. Migrate up or migrate down.
	With this library you can now do this. This library is not complete, please read
	http://codeigniter.com/wiki/Migrations for future needs and issues. This "fork" of 
	Mat'as orginal work just tweets something to work better in our work. Both Libraries
	are powerful and work in nearly the same way. Maybe someday we can create a joint project 
	with Mat'as or even better get this into that core of Codeigniter.

	Copy the files to these locations.
	migrate.php -> application/libraries/
	dbmigrate.php -> applcation/controllers/

	The migration files included in this are just examples. You should install them where ever you 
	point your $config["migrations_path"] to.
	Add these config to your config.php

	| Enable/Disable Migrations
	| Migrations are disabled by default for security reasons.
	| You should enable migrations whenever you intend to do a schema migration
	| and disable it back when you're done.
	| Some more severe security measures might take place in future releases.
	$config["migrations_enabled"] = TRUE;

	| Migrations Path
	| Path to your migrations folder.
	| Typically, it will be within your application path.
	| Also, writing permission is required within the migrations path.
	$config["migrations_path"] = APPPATH . "migrations/";

	| Migrations version
	| This is used to set the default migration for this code base. 
	| Sometimes you want the system to automaticly migrate the database
	| to the most current migration. Or there might be higher migrations
	| that are not part of the production env. Setting the migration does 
	| does nothing here. It is a way for a programer to check the config.
	| On login you might want to do something like this 
	| $this->migrate->version($this->config->item('migrations_version'));
	$config["migrations_version"] = 6;
	The code is all based out of a library so you can call it anywhere with.
	$this->migrate->setverbose(TRUE); // echo statments or not
	$this->migrate->version(id); // migrate the database to a particular version
	$this->migrate->install(); // install to the latest version.

	The dbmigreate.php controller just shows the use of these functions. If you are going to use it.
	remove the 'die();' and put it back in place when you are done.

	At the bottom of migreate.php we assume you are keeping track of your versions with a db table called config. Yes
	you can not use this migration script to create that table. You need at least one table installed to boot strap this.
	You will want to review the _update_schema_version() function to either modify or copy how it works. 

	Also, in our applcations we have this code to set our applcation configs. We do not believe in writting to the file system
	that is what a database is for :).

	// Setup Config.
	function setup_system_config()
		$query = $this->db->get('config');
		foreach ($query->result() AS $row)
			$this->config->set_item($row->Config_Name, $row->Config_Data);

	In this code we set. $this->CI->config->item('migrationversion'); and that is how _get_schema_version() 
	gets the current version. This is the version this database is set too.

	** Suggestion **
	We also do this on login to make sure this database is migrated to the version the config files wants it to be migrated too.
	// Make sure our database is up-to-date
	if(! $this->migrate->version($this->config->item('migrations_version')))

	Over all you should read this and http://codeigniter.com/wiki/Migrations to get an over all feel for this and make any changes 
	you need for your applcation.

Other Helpful Stuff:

Included in this git repo is an example system.php file. A way to have migrations run on every page load. You can copy it directly or use it as an example for your own code structure. 

When you auto load the system.php lib this should be your order: $autoload['libraries'] = array('database', 'migrate', 'system', 'session');

Here is a video walk through of migrations in action.