Migrations

• Usage
  • Enabling migrations
  • Creating migrations
  • Running migrations
  • Rolling back migrations
• Multiple databases
• Dependency injection

Database migrations offer a convenient way to alter your databases in a structured and organized manner. They allow you to commit and roll back schema changes.

Mako migrations are created and executed from the reactor CLI tool.

Usage

Enabling migrations

You need to add a table called mako_migrations to your database. The table will be used to keep track of the migrations that have been ran. Here's the SQL for creating the table using MySQL:

CREATE TABLE `mako_migrations`
(
	`batch` int(10) unsigned NOT NULL,
	`package` varchar(255) DEFAULT NULL,
	`version` varchar(255) NOT NULL
);

Creating migrations

Creating a migration is done from the reactor CLI tool:

// Creates an application migration

php reactor migrate.create

// Creates a migration for the "foobar" package

php reactor migrate.create --package="vendor/package"

// Creates a migration with a description

php reactor migrate.create --description="Creates session table"

Running the create commands will return the following messages:

Migration created at "/var/www/app/migrations/Migration_20140824100019.php".

Migration created at "/var/www/app/packages/foobar/migrations/Migration_20140824100317.php".

Migration created at "/var/www/app/migrations/Migration_20140824100019.php".

The generated migration will contain a skeleton class with two methods, up and down.

<?php

class Migration_20120824100019 extends Migration
{
	/**
	 * Makes changes to the database structure.
	 */
	public function up()
	{
		$this->getConnection()->query
		(
			// Write your SQL here
		);
	}

	/**
	 * Reverts the database changes.
	 */
	public function down()
	{
		$this->getConnection()->query
		(
			// Write your SQL here
		);
	}
}

Every migration is executed inside a transaction if the database supports transactional DDL (PostgreSQL and SQLite). You can disable the use of transactions by setting the $useTransaction property to false.

Running migrations

You can check if there are any outstanding migrations using the status command:

php reactor migrate.status

If there are outstanding migrations then you can run them like this:

php reactor migrate.up

This will show you the names of the migrations that were executed:

Ran the following migrations:

+-------------------------------------------+-----------------------+
| Migration                                 | Description           |
+-------------------------------------------+-----------------------+
| Migration_20140824100019                  |                       |
| Migration_20140824100317 (vendor/package) |                       |
| Migration_20140824100019                  | Creates session table |
+-------------------------------------------+-----------------------+

Rolling back migrations

If you need to revert the changes made to your database then you can use the down command. This will roll back the last batch of migrations executed.

php reactor migrate.down

This will show you the migrations that were rolled back:

Rolled back the following migrations:

+-------------------------------------------+-----------------------+
| Migration                                 | Description           |
+-------------------------------------------+-----------------------+
| Migration_20140824100019                  | Creates session table |
| Migration_20140824100317 (vendor/package) |                       |
| Migration_20140824100019                  |                       |
+-------------------------------------------+-----------------------+

You can roll back multiple batches by telling the rollback command how many batches you want to roll back using the batches option.

php reactor migrate.down --batches=2

If you want to roll back all database changes in one go then you can use the reset command.

php reactor migrate.reset

This will prompt you for confirmation. To force the reset just use the force option.

php reactor migrate.reset --force

Multiple databases

All transactions are normally executed against the default database of your application. You can override this by using the $connectionName property of the migration class.

Running migrations for the non-default database requires you to use the optional database option of the migrate.status, migrate.up, migrate.down and migrate.reset commands.

Note that each database requires its own mako_migrations table.

Dependency injection

Migrations are instantiated by the dependency injection container. This makes it easy to inject your dependencies using the constructor.

<?php

class Migration_20120824100019 extends Migration
{
	protected $config;

	public function __construct(ConnectionManager $connectionManager, Config $config)
	{
		parent::__construct($connectionManager);

		$this->config = $config;
	}
}

Note that migrations expect the first constructor parameter to be an instance of the ConnectionManager class.

You can also inject dependencies directly into the up and down methods since they are executed by the Container::call() method.

public function down(LoggerInterface $log)
{
	$log->info('Executed the down method of the ' . static::class . ' migration');
}

Migrations are also container aware. You can read more about what this means here.