Sql Migrate - working example

Ok I just spend 8 hours with the migration module. I was not able to find just one working example for the migration of sql data. Even Drupal's own documentation has the state "outdated".

I am trying to import just titles - so that should be pretty straightforward. Unfortunately, I do not even get an error when trying to import the configuration nor by the source plugin.

test_migrate_er.info.yml - (the module is enabled)

name: Test Migrate ER
type: module
description: 'Importer for news nodes via sql ("test" // Typo 3)'
package: test
version: VERSION
core_version_requirement: ^8.8.0 || ^9.0
project: 'test_migrate_er'

dependencies:
  - drupal:migrate
  - drupal:migrate_tools
  - drupal:migrate_plus

migrate_plus.migration_group.test_migrate_content.yml (this is imported via "drush cim")

uuid: 366085cb-4cea-49d1-84a0-534afd31b114
langcode: en
status: true
dependencies: {  }
id: test_migrate_content
label:"TEST IMPORT"
description: null
source_type: null
module: null
shared_configuration: null
source:
  plugin: test_source
  key: migrate

The database connection is set in the local.settings.php (it does use the source key)

$databases['migrate']['default'] = [...]

When importing thr configuration all seems good - no errors ... but when exporting it the source bit including sub-elements (plugin and key) are gone as if they are invalid attributes. That would also explain why the plugin / migration is never shown when testing via drush ms. Seems that the configuration parser is ignoring it.

Source Plugin (/web/modules/custom/test_migrate_er/src/Plugin/migrate/source/News.php. -- the module "test_migrate_er" is enabled)

<?php

namespace Drupal\test_migrate_er\Plugin\migrate\source;

use Drupal\migrate\Plugin\migrate\source\SqlBase;
use Drupal\migrate\Row;

/**
 * Minimalistic example for a SqlBase source plugin.
 *
 * @MigrateSource(
 *   id = "test_source",
 *   source_module = "test_migrate_er",
 * )
 */
class News extends SqlBase {

  /**
   * {@inheritdoc}
   */
  public function query() {
    // Source data is queried from 'curling_games' table.
    $query = $this->select('tx_news_domain_model_news_copy', 'n')
      ->fields('n', [
        'uid',
        'tstamp',
        'crdate',
        'datetime',
        'title',
        'teaser',
        'bodytext',
      ]);
    return $query;
  }



  /**
   * {@inheritdoc}
   */
  public function fields() {
    $fields = [
      'uid' => $this->t('uid' ),
      'tstamp' => $this->t('tstamp' ),
      'crdate' => $this->t('crdate' ),
      'datetime' => $this->t('datetime' ),
      'title' => $this->t('title' ),
      'teaser' => $this->t('teaser' ),
      'bodytext' => $this->t('bodytext' ),
    ];
    return $fields;
  }

  /**
   * {@inheritdoc}
   */
  public function getIds() {
    return [
      'uid' => [
        'type' => 'integer',
        'alias' => 'n',
      ],
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function prepareRow(Row $row) {
    // This example shows how source properties can be added in
    // prepareRow(). The source dates are stored as 2017-12-17
    // and times as 16:00. Drupal 8 saves date and time fields
    // in ISO8601 format 2017-01-15T16:00:00 on UTC.
    // We concatenate source date and time and add the seconds.
    // The same result could also be achieved using the 'concat'
    // and 'format_date' process plugins in the migration
    // definition.
//    $date = $row->getSourceProperty('date');
//    $time = $row->getSourceProperty('time');
//    $datetime = $date . 'T' . $time . ':00';
//    $row->setSourceProperty('datetime', $datetime);
    return parent::prepareRow($row);
  }
}

You find a ton "migration" example codes ... non of them target sql and non of them seem to be up to date. I wonder if anybody knows a working example or at least a correct documentation. That would make the next days so much more enjoyable :)

Thanks for help