README.md

Simple Migration Management

Modeled after my experience using Laravel's implementation, but much simpler implementation.

Requires

• Config_Lite initialized with:
  • config.ini with:
    • env entry (development|production)
    • internal section with
      • migration_ver entry >= 0
• PDO object

Migration.php

<?php

/**
 * Migration
 */
abstract class Migration
{
    protected $db;
    protected $dbName;

    public function __construct($db, $dbName)
    {
        $this->db     = $db;
        $this->dbName = $dbName;
    }

    abstract public function up();

    abstract public function down();
}

MigrationManager.php

<?php

/**
 * Database Management
 */
class MigrationManager
{
    public $version;
    public $maxMigrationVersion;

    protected $db;
    protected $config;
    protected $configSection;
    protected $env;
    protected $migrationsLocation;
    protected $migrations = array();

    /**
     * Constructor
     * @param PDO           $db                 DB Connection object
     * @param Config_Lite   $config             Configuration Object
     * @param string        $migrationsLocation Path to migrations folder
     */
    public function __construct($db, $config, $migrationsLocation = __DIR__ . '/migrations')
    {
        $this->db                 = $db;
        $this->config             = $config;
        $this->env                = $config->get(null, 'env');
        $this->configSection      = ($config->get(null, 'env') == 'development') ? 'db_development' : 'db_production';
        $this->migrationsLocation = $migrationsLocation;
        $this->version            = $this->readMigrationVersion();

        $this->getMigrations();
    }

    /**
     * Process migrations not executed
     * @return void
     */
    public function migrate()
    {
        foreach ($this->migrations as $migration) {
            if ($migration['number'] <= $this->version) {
                continue;
            }
            require_once $this->migrationsLocation . '/' . $migration['filename'];
            $m = new $migration['class'](
                $this->db, // db object
                $this->config->get($this->configSection, 'database') // db name
            );
            $m->up();
            $this->version = $migration['number'];
        }

        $this->writeMigrationVersion();
    }

    /**
     * Reverse migrations
     * @return void
     */
    public function reset()
    {
        // reverse
        arsort($this->migrations);
        foreach ($this->migrations as $migration) {
            $m = new $migration['class'];
            $m->down();
            $this->version = $migration['number'] - 1;
        }
        // re-sort
        asort($this->migrations);
        $this->writeMigrationVersion();
    }

    /**
     * Get migrations defined
     * @return void  Sets instance variable $migrations
     */
    public function getMigrations()
    {
        $dir = new DirectoryIterator($this->migrationsLocation);
        foreach ($dir as $fileinfo) {
            if (!$fileinfo->isDot()) {
                $parsedData = $this->parseMigrationFilename($fileinfo->getFilename());
                if (!empty($parsedData)) {
                    $this->migrations[$fileinfo->getFilename()] = $parsedData;
                }
            }
        }
        asort($this->migrations);
        $last                  = end($this->migrations);
        $this->maxMigrationVersion = $last['number'];
    }

    /**
     * Check if database exists
     * @return bool
     */
    public function databaseExists()
    {
        $stmt = $this->db->query("
            SELECT
                COUNT(*)
            FROM
                INFORMATION_SCHEMA.SCHEMATA
            WHERE
                SCHEMA_NAME = '" . $this->config->get($this->configSection, 'database') . "'
        ");
        return (bool) $stmt->fetchColumn();
    }

    /**
     * Parse migration filename for number, class name
     * @param  string $filename Migration filename
     * @return array            Migration filenames, numbers, class names
     */
    private function parseMigrationFilename($filename)
    {
        $return = array();

        $regex = '/^(\d+)_(.*).(php)$/';
        preg_match($regex, $filename, $data);

        if (!empty($data)) {
            $return = array(
                'filename' => $filename,
                'class'    => $data[2],
                'number'   => (integer) ltrim($data[1], '0'), // remove leading zeros
            );
        }

        return $return;
    }

    /**
     * Read migration version from .env.ini
     * @return integer
     */
    private function readMigrationVersion()
    {
        return (integer) $this->config->get('internal', 'migration_ver');
    }

    /**
     * Write migration version to .env.ini
     * @return void
     */
    private function writeMigrationVersion()
    {
        $this->config->set('internal', 'migration_ver', $this->version);
        $this->config->save();
    }
}