# Migrations

Database migrations can be brought by plugins and AdditionalBundles.

If you want to know more about migrations you can follow the steps from the Shopware documentation:

{% embed url="<https://developer.shopware.com/docs/concepts/framework/migrations.html#migrations>" %}

All migrations are located in the *Migration/*-directory of your plugin or AdditionalBundle per default.

## Adding a migration to an AdditionalBundle

Shopware provides the `database:create-migration` console command to easily create a new migration.

To create a new migration in an AdditionalBundle you must call the command with some options:

```bash
bin/console database:create-migration --name=<name> path/to/your/bundle/migration/dir Your\\Bundle\\Migration\\Namespace
```

The following example command adds a migration *MyMigration* to the *Migration/*-directory of the *FooBundle:*

```bash
bin/console database:create-migration --name=MyMigration custom/plugins/FooPlugin/FooBundle/Migration Foo\\Bundle\\Migration
```

## Delete data on plugin uninstallation

If you have some migrations which add new database tables you also want to delete these tables on plugin uninstallation. dustin/shopware-utils automatically takes care about that! The only thing you need to do is to tell which tables need to be deleted on plugin uninstallation.

Overwrite the `getTablesToRemove` -method of your plugin or AdditionalBundle.

{% tabs %}
{% tab title="Plugin" %}

```php
<?php

namespace Foo\Bar;

use Dustin\ShopwareUtils\Core\Framework\Plugin;

class FooBar extends Plugin
{
    public function getTablesToRemove(): array {
        return [
            'my_first_table',
            'my_second_table'
        ];
    }
}
```

{% endtab %}

{% tab title="AdditionalBundle" %}

```php
<?php

namespace Foo\Bundle;

use Dustin\ShopwareUtils\Core\Framework\AdditionalBundle;

class FooBundle extends AdditionalBundle
{
    public function getTablesToRemove(): array {
        return [
            'my_first_table',
            'my_second_table'
        ];
    }
}
```

{% endtab %}
{% endtabs %}

dustin/shopware-utils will  execute the following steps to remove your tables from database:

1. Execute a DELETE-statement for each table in the given order. All statements will be executed in a single transaction. If there is an error and the transaction fails a rollback will be executed and the exception will be thrown. If the transaction is successful all tables should be present but with no data.
2. Execute a DROP TABLE-statement for each table in the given order.

{% hint style="warning" %}
DELETE-statements will be executed in the given order. If you want two tables to be deleted which have foreign key constraints you have to list the associated entity first.<br>

Example:

You have two entities:

* my\_entity
* my\_entity\_association (with a foreign key and ON DELETE RESTRICT constraint )

You must provide the entities in the following order to prevent an exception:

1. my\_entity\_association
2. my\_entity
   {% endhint %}


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