root/trunk/application/controllers/migrate.php

<?php 
/*
 * Created on 2008 Jun 22
 * by Martin Wernstahl <m4rw3r@gmail.com>
 */
class migrate extends Controller{
    var $ignore_classes = array('array','array_object','migrate','controller');
    function migrate(){
        parent::Controller();
        $this->load->database();
        $this->load->dbforge();
        $this->load->helper('url');
        if(file_exists(APPPATH.'/current_db_ver.txt'))
            $this->current = file_get_contents(APPPATH.'/current_db_ver.txt');
        else
            $this->current = 0;
    }
    function index(){
        $classes = array();
        foreach(get_declared_classes() as $class){
            if(stripos($class,'migrate') !== false && $class != 'migrate' && class_exists($class)){
                $classes[] = $class;
            }
        }
?>
<ul>
<?php foreach($classes as $class){
    $version = substr($class,8);
    echo "<li>".anchor('migrate/to/'.$version,$version)."</li>";
}
?>
</ul>

<?php
    }
    function to($version){
        if($version == $this->current){
            echo "<p>already at version $version</p>";
            return;
        }
        if($this->current < $version)
            $inc = 2;
        else
            $inc = 0;
        for($i = $this->current + $inc; ($i <= $version && $inc == 2) || ($i > $version && $inc == 0); $i = $i - 1 + $inc){
            $name = "migrate_".str_pad($i,3,'0',STR_PAD_LEFT);
            $obj = new $name();
            if($inc == 1)
                $obj->up($this);
            else
                $obj->down($this);
        }
        file_put_contents(APPPATH.'/current_db_ver.txt',$version);
        echo "<p>Done migrating to version $version</p>";
    }
}
class migrate_002{
    function up($CI){
        echo "going to version 2";
    }
    function down($CI){
        echo "going down from version 2";
    }
}
class migrate_001 extends IRM{
    function up(&$CI){
        echo "going to version 1";
        /*table('testaaaa')
            ->column('id')
                ->type('int')
                ->options(array('auto_increment' => true,
                    'unsigned' => true))
                ->primary(true)
                ->end()
            ->column('lft')
                ->type('int')
                ->options(array('unsigned' => true))
                ->index(true)
                ->end()
            ->column('rgt')
                ->type('int')
                ->options(array('unsigned' => true))
                ->end()
            ->column('title')
                ->type('varchar')
                ->options(array('constraint' => 100))
                ->end()
                    ->execute();*/
    }
}
/**
 * 
 */
abstract class IRM{
    function IRM(){
        $CI =& get_instance();
        $this->db =& $CI->db;
        $this->dbforge =& $CI->dbforge;
    }
    abstract function up(&$CI);
    function down(&$CI){
        echo '!!!!';
    }
}
class IRM_table{
    var $columns = array();
    var $name;
    var $new_name;
    var $db;
    var $edited = true;
    var $new = true;
    function IRM_table($name, $options){
        $this->name = $name;
        $this->options = $options;
        $CI =& get_instance();
        $this->db =& $CI->db;
        $this->dbforge =& $CI->dbforge;
        $this->_load();
    }
    function _load(){
        if($this->db->table_exists($this->name)){
            foreach($this->db->list_fields($this->name) as $col){
                $obj  = new IRM_column($this->name,array($col, 'table_obj' => &$this));
                $obj->existing_name = $col;
                $obj->edited = false;
                $this->columns[] = $obj;
            }
            $this->edited = false;
            $this->new = false;
        }
    }
    function &rename($name){
        $this->new_name = $name;
        return $this;
    }
    function &column($name = null, $type = null, $options = array()){
        foreach($this->columns as $col){
            if($col->name == $name)
                return $col;
        }
        $args = array_merge(func_get_args(), array('table_obj' => &$this));
        $col = new IRM_column($this->name, $args);
        $this->columns[] =& $col;
        return $col;
    }
    function drop(){
        $this->dbforge->drop_table($this->name);
    }
    function execute(){
        if($this->new){
            foreach($this->columns as $column){
                if($column->edited == true)
                    $column->execute(true);
            }
        }
        if($this->edited == true)
            $this->dbforge->create_table($this->name, TRUE);
        if(!$this->new){
            foreach($this->columns as $column){
                if($column->edited == true)
                    $column->execute();
            }
        }
        if($this->new_name){
            $this->dbforge->rename_table($this->name,$this->new_name);
            $this->name = $this->new_name;
            foreach($this->columns as $col){
                $col->table = $this->name;
            }
        }
    }
}
class IRM_column{
    var $table;
    /**
     * The new settings for this column
     */
    var $opts;
    var $name;
    var $existing_name;
    var $type;
    var $edited = true;
    var $drop = false;
    var $index = false;
    var $primary = false;
    function IRM_column($table, $options = array()){
        $this->table = $table;
        $this->name = isset($options[0]) && $options[0] != null ? $options[0] : null;
        $this->type = isset($options[1]) && $options[1] != null ? $options[1] : null;
        $this->opts = isset($options[2]) && $options[2] != null ? $options[2] : array();
        $this->table_obj = isset($options['table_obj']) ? $options['table_obj'] : null;
        $CI =& get_instance();
        $this->db =& $CI->db;
        $this->dbforge =& $CI->dbforge;
    }
    function &name($name){
        $this->name = $name;
        $this->edited = true;
        return $this;
    }
    function &type($type){
        $this->type = $type;
        $this->edited = true;
        return $this;
    }
    function &primary($val = true){
        $this->primary = $val;
        $this->edited = true;
        return $this;
    }
    function &index($val = true){
        $this->index = $val;
        $this->edited = true;
        return $this;
    }
    function &options($options){
        $this->opts = $options;
        $this->edited = true;
        return $this;
    }
    function &drop(){
        $this->drop = true;
        $this->edited = true;
        return $this;
    }
    function execute($new = false){
        if($this->edited){
            if($this->drop && !$new){
                $this->dbforge->drop_column($this->table, $this->name);
                return;
            }
            if(!$new && $this->existing_name != null && $this->existing_name != $this->name){
                // rename
                $opts = array_merge(array(
                        'name' => $this->name,'type' => $this->type),$this->opts);
                $opts = array(
                        $this->existing_name => $opts);
                $this->dbforge->modify_column($this->table,$opts);
            }
            else{
                // add
                $opts = array_merge(array('type' => $this->type),$this->opts);
                $opts = array($this->name => $opts);
                if($new){
                    $this->dbforge->add_field($opts);
                }
                else{
                    $this->dbforge->add_column($this->table,$opts);
                }
            }
            if($this->primary){
                $this->dbforge->add_key($this->name, true);
            }
            if($this->index){
                $this->dbforge->add_key($this->name);
            }
        }
    }
    function &end(){
        return $this->table_obj;
    }
}
function &table($name, $options = array()){
    $table = new IRM_table($name, $options);
    return $table;
}
function &add_column($table, $name, $type = 'int', $options = array()){
    $obj = new IRM_column($table,array($name,$type,$options));
    $obj->execute();
}
?>