Migrations

Migrations guide

Migrations are PHP classes containing database schema changesets. These changesets can be applied or reverted to bring the database into a certain state. You might know the concept of migrations from other Frameworks or Symfony as well. Read on to find out how to add your own migrations to Shopware when implementing a plugin.

Adding your own migrations

For Shopware to recognise additional plugin migrations, they need to be placed in the Migration directory under your plugin's source code root directory:

./
+-- SwagExamplePlugin/
    +-- src/
        +-- Migration/
            +-- # Place migrations here
        +-- SwagExamplePlugin.php

Each migration filename follows a pattern described here . To ease plugin development, Shopware provides a console command which can be used to generate a correctly named migration file with the default methods needed. You may use this command to create a migration for your plugin:

php bin/console database:create-migration \
  -p SwagExamplePlugin \
  --name CreateSwagEntity

After running this command, you should find a new migration file under your plugins source code root directory:

./
+-- SwagExamplePlugin/
    +-- src/
        +-- Migration/
            +-- Migration1587651945CreateSwagEntity.php
        +-- SwagExamplePlugin.php

Modifying the database

Now that you've created the migration file, open it in your editor or IDE. There should already be two methods written out, namely update and updateDestructive. The update method may contain only non-destructive changes which can be rolled back at any time. The updateDestructive method should contain destructive changes, which cannot be reversed, like dropping columns or tables.

Let's create a table for testing out the migration, you can use the following example implementation for this:

public function update(Connection $connection): void
{
    $sql = <<<'SQL'
CREATE TABLE IF NOT EXISTS `swag_example_entity` (
    `id`   BINARY(16)                              NOT NULL,
    `name` VARCHAR(255) COLLATE utf8mb4_unicode_ci NULL
  PRIMARY KEY (`id`),
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
SQL;

    $connection->executeUpdate($sql);
}

Running the migration

For testing purposes, you can apply the new migration using
this console command
php bin/console database:migrate --all SwagExamplePlugin

If you now have a look at your database, the new swag_example_entity table should have been created.

From now on, this migration will be automatically applied when the plugin is installed, but you may also control this behaviour in detail if you wish to.

Important Rules

To ensure the stability of updates and Shopware itself, it is imperative that the following rules are always followed when creating new migrations.

1. Migrations must be able to be executed more than once

If a migration fails, make sure that it can be executed again. A migration should check whether structures have already been created to avoid creating duplicates.

2. Do not trust any identifier

Identifiers on a customer system can always be different from those on a development environment, for example. Search in detail for trusted identifiers. If in doubt, a database query for the identifier must be initiated in advance.

3. Do not trust customer data

Customers sometimes produce very complex and unpredictable data constructs. Therefore, never rely on the existence of data or structures. Always program migrations very defensively with exact queries on the situation.

4. Duration (Performance)

A migration must never take longer than 10 seconds on your local system. You do not know the timeout values of the customers, so this value should never be exceeded. Customer systems are often slower than developer systems, but contain a lot of data. Make sure to test your migration with big data sets.

5. Don't hurt customized Data

There are data that are often individualized by customers. Under no circumstances may a migration overwrite individualized customer data. Always check this in your migration.

6. There are no default languages

The customers can select any language as their default. Don't rely on any language as given, neither English nor German.

7. Test data migration

If data is updated in a migration, a test must be written for this migration.

8. NEVER update a migration

You cannot alter a migration which was already part of a released version. You will need to write a new migration to do the changes, otherwise an existing system will not get the same data structure on update as a new installation. The only exception to this rule is when the migration throws an error.

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