Migrate Chosen from D7 to D9.

1. +++ b/chosen.module
   @@ -150,3 +153,18 @@ function chosen_help($route_name, RouteMatchInterface $route_match) {
   +function chosen_migration_plugins_alter(array &$migrations) {
   +  $chosen_migration = array_filter(
   +    $migrations,
   +    function ($definition) {
   +      return $definition['id'] === 'd7_field_instance_widget_settings';
   +    }
   +  );
   +  foreach (array_keys($chosen_migration) as $plugin_id) {
   +    $migrations[$plugin_id]['process']['options/type'][] = ['plugin' => 'chosen'];
   +  }
   +}
   

   We need our usual check whether the chosen module is enabled on the source.

   If it isn't, then we shouldn't migrate its settings, nor modify the field widget settings migration.

2. +++ b/migrations/d7_chosen_settings.yml
   @@ -0,0 +1,38 @@
   +  plugin: variable
   +  variables:
   +    - chosen_minimum_single
   +    - chosen_minimum_multiple
   +    - chosen_disable_search_threshold
   +    - chosen_minimum_width
   +    - chosen_jquery_selector
   +    - chosen_search_contains
   +    - chosen_disable_search
   +    - chosen_include
   +    - chosen_allow_single_deselect
   +    - chosen_placeholder_text_multiple
   +    - chosen_placeholder_text_single
   +    - chosen_no_results_text
   +    - chosen_disabled_themes
   

   It would be nice to add the source_module: chosen configuration here.

3. +++ b/migrations/d7_chosen_settings.yml
   @@ -0,0 +1,38 @@
   +  minimum_single: chosen_minimum_single
   

   We have to properly handle the default values here:

   I checked only chosen_minimum_single: Its default value in Drupal 7 is 20 (and it can be configured to be (int) 0, so this process plugin should be:

   minimum_single:
     plugin: default_value
     source: chosen_minimum_single
     strict: true
     default_value: 20
   

   Please check the other Drupal 7 variables as well, and update the process pipeline accordingly!

4. +++ b/src/Plugin/migrate/process/Chosen.php
   @@ -0,0 +1,29 @@
   +class Chosen extends ProcessPluginBase {
   +
   +  /**
   +   * {@inheritdoc}
   +   */
   +  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
   +    if ($value !== 'options_select' || empty($row->getSourceProperty('widget/settings/apply_chosen'))) {
   +      return $value;
   +    }
   +    return 'chosen_select';
   +  }
   +
   +}
   

   👍 Very elegant and clear!

I still have to nits (and I'm very sorry I didn't notice them before).
But other than that, #6 is perfect!

1. +++ b/chosen.module
   @@ -7,10 +7,16 @@
   +use Drupal\migrate\Plugin\MigrateSourceInterface;
   +use Drupal\migrate\Plugin\MigrationInterface;
   +use Drupal\migrate\Row;
   

   These classes aren't used.

2. +++ b/tests/src/Kernel/ChosenMigrationTest.php
   @@ -0,0 +1,86 @@
   +  /**
   +   * Tests Chosen data and field widget migration.
   +   */
   +  public function testFocalPointMigration(): void {
   

   This test method should be renamed!

Hi!

Shoudn't this be a separate module?

For example: https://www.drupal.org/project/webform_migrate
https://www.drupal.org/project/media_migration
https://www.drupal.org/project/paragraphs_migration

Re @nagy.balint, I don't think so. This migration path consists of only:

• A migration YAML that migrates D7 settings to D9, and
• A hook_migration_plugins_alter() implementation and a migrate process plugin which migrate the right form widget for the fields which are using Chosen in the source Drupal 7 instance.

The bulk of the patch is a Drupal 7 database fixture and a migration test that uses that fixture to prove it works as expected.

If you check the modules you mentioned, they have a huge codebase. Chosen's situation is much simpler imho. https://git.drupalcode.org/project/address/-/tree/8.x-1.x/src/Plugin/mig...

Re #8:
This is now perfect! 🥳

Shouldnt it be a sub module the very least?

After further research, it seems that its only me who finds it weird to have these in the main module.

So then I can commit it.

Thank you!