Migration from Drupal 7: Why You Should Start with a Clean Slate ✨

// Overly complex field with endless hook_form_alter function mymodule_form_article_node_form_alter(&$form, &$form_state, $form_id) { // Add special validators for field combinations if (isset($form['field_related_content']) && isset($form['field_product_reference'])) { $form['#validate'][] = 'mymodule_validate_related_content'; } // Hide/show fields based on other values $form['field_product_reference']['#states'] = array( 'visible' => array( ':input[name="field_content_type[und]"]' => array('value' => 'product'), ), ); // 50+ more lines of specific logic... } 

// Creating a paragraph type through configuration $paragraphType = ParagraphsType::create([ 'id' => 'product_reference', 'label' => 'Product Reference', ]); $paragraphType->save(); // Behavior in the Parameter Entity Reference field class ProductReferenceBehavior extends ParagraphsBehaviorBase { public function buildBehaviorForm(ParagraphInterface $paragraph, array &$form, FormStateInterface $form_state) { $form['display_price'] = [ '#type' => 'checkbox', '#title' => $this->t('Display product price'), '#default_value' => $paragraph->getBehaviorSetting('product_reference', 'display_price', FALSE), ]; return $form; } } 

<?php namespace Drupal\my_migration\Plugin\migrate; use Drupal\migrate\Plugin\Migration; use Drupal\migrate\Row; use Drupal\migrate\Plugin\MigrationInterface; /** * @Migration( * id = "custom_article_migration", * source = { * "plugin" = "d7_node", * "node_type" = "article" * }, * destination = { * "plugin" = "entity:node", * "default_bundle" = "article" * }, * process = { * "title" = "title", * "body/value" = "body/0/value", * "body/format" = "body/0/format", * "field_tags" = { * "plugin" = "migration_lookup", * "migration" = "d7_taxonomy_term", * "source" = "field_tags" * }, * "field_image" = { * "plugin" = "migration_lookup", * "migration" = "d7_file", * "source" = "field_image" * } * }, * migration_dependencies = { * "required" = { * "d7_taxonomy_term", * "d7_file" * } * } * ) */ class CustomArticleMigration extends Migration { /** * {@inheritdoc} */ public function prepareRow(Row $row) { // Get old data $old_body = $row->getSourceProperty('body/0/value'); // Transform content (example: update image format) if ($old_body) { $new_body = preg_replace( '/<img src="\/sites\/default\/files\/([^"]+)"/', '<img src="/sites/default/files/new_structure/$1"', $old_body ); // Add Bootstrap 5 classes $new_body = str_replace('<table>', '<table class="table table-striped">', $new_body); // Update the row $row->setSourceProperty('body/0/value', $new_body); } // Combine multiple old fields into one new paragraph field $featured = $row->getSourceProperty('field_featured'); $highlight_color = $row->getSourceProperty('field_highlight_color'); if ($featured == 1) { $paragraph_data = [ 'type' => 'featured_content', 'field_color' => $highlight_color ?: 'blue', 'field_display_mode' => 'highlighted', ]; $row->setSourceProperty('field_content_components', [$paragraph_data]); } return parent::prepareRow($row); } } 

<?php namespace Drupal\custom_course_api\Controller; use Drupal\Core\Controller\ControllerBase; use Drupal\Core\Cache\CacheableJsonResponse; use Drupal\Core\Cache\CacheableMetadata; use Drupal\node\Entity\Node; use Symfony\Component\HttpFoundation\Request; use Symfony\Component\DependencyInjection\ContainerInterface; use Drupal\Core\Entity\EntityTypeManagerInterface; /** * Controller for the courses API. */ class CoursesApiController extends ControllerBase { /** * Entity type manager. * * @var \Drupal\Core\Entity\EntityTypeManagerInterface */ protected $entityTypeManager; /** * {@inheritdoc} */ public static function create(ContainerInterface $container) { return new static( $container->get('entity_type.manager') ); } /** * Constructor. * * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager * Entity type manager. */ public function __construct(EntityTypeManagerInterface $entity_type_manager) { $this->entityTypeManager = $entity_type_manager; } /** * Returns a list of courses in JSON format. * * @param \Symfony\Component\HttpFoundation\Request $request * Request object. * * @return \Drupal\Core\Cache\CacheableJsonResponse * JSON response with course data. */ public function getCourses(Request $request) { $category = $request->query->get('category'); $limit = $request->query->get('limit', 10); // Base query for courses $query = $this->entityTypeManager->getStorage('node')->getQuery() ->condition('type', 'course') ->condition('status', 1) ->sort('created', 'DESC') ->range(0, $limit); // Add filter by category if specified if ($category) { $query->condition('field_course_category', $category); } $nids = $query->execute(); $courses = []; $cache_metadata = new CacheableMetadata(); foreach ($nids as $nid) { $node = Node::load($nid); $cache_metadata->addCacheableDependency($node); // Structure data for the API $courses[] = [ 'id' => $node->id(), 'title' => $node->label(), 'description' => $node->field_description->value, 'duration' => $node->field_duration->value, 'image' => $node->field_image->entity ? $node->field_image->entity->createFileUrl() : NULL, 'lessons' => $this->getLessonsData($node), ]; } $response = new CacheableJsonResponse($courses); $response->addCacheableDependency($cache_metadata); return $response; } /** * Gets lesson data for a course. * * @param \Drupal\node\Entity\Node $course * Course node. * * @return array * Array with lesson data. */ protected function getLessonsData(Node $course) { $lessons = []; if ($course->hasField('field_lessons') && !$course->field_lessons->isEmpty()) { foreach ($course->field_lessons->referencedEntities() as $lesson) { $lessons[] = [ 'id' => $lesson->id(), 'title' => $lesson->label(), 'preview' => $lesson->field_preview->value, ]; } } return $lessons; } } 

<?php /** * Implements hook_preprocess_node(). */ function mytheme_preprocess_node(&$variables) { if ($variables['type'] == 'course') { // Check various conditions and add many template variables $node = $variables['node']; // Custom logic for determining course status if (!empty($node->field_start_date) && !empty($node->field_end_date)) { $start = strtotime($node->field_start_date[LANGUAGE_NONE][0]['value']); $end = strtotime($node->field_end_date[LANGUAGE_NONE][0]['value']); $now = time(); if ($now < $start) { $variables['course_status'] = 'upcoming'; $variables['course_classes'] = 'course--upcoming'; } elseif ($now > $end) { $variables['course_status'] = 'completed'; $variables['course_classes'] = 'course--completed'; } else { $variables['course_status'] = 'active'; $variables['course_classes'] = 'course--active'; } } // Heavy queries and business logic in the template if (!empty($node->field_course_category)) { $term_id = $node->field_course_category[LANGUAGE_NONE][0]['tid']; $term = taxonomy_term_load($term_id); $variables['category_name'] = $term->name; // Complex query for related courses $related_query = new EntityFieldQuery(); $related_query->entityCondition('entity_type', 'node') ->entityCondition('bundle', 'course') ->propertyCondition('status', 1) ->fieldCondition('field_course_category', 'tid', $term_id) ->propertyCondition('nid', $node->nid, '!=') ->range(0, 3); $result = $related_query->execute(); if (isset($result['node'])) { $related_nids = array_keys($result['node']); $related_nodes = node_load_multiple($related_nids); $variables['related_courses'] = array(); foreach ($related_nodes as $related_node) { $variables['related_courses'][] = array( 'title' => $related_node->title, 'link' => url('node/' . $related_node->nid), ); } } } } } 

<?php namespace Drupal\custom_course\Service; use Drupal\Core\Entity\EntityTypeManagerInterface; use Drupal\Core\Datetime\DrupalDateTime; use Drupal\node\NodeInterface; /** * Service for working with courses. */ class CourseService { /** * Entity type manager. * * @var \Drupal\Core\Entity\EntityTypeManagerInterface */ protected $entityTypeManager; /** * Constructor. * * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager * Entity type manager. */ public function __construct(EntityTypeManagerInterface $entity_type_manager) { $this->entityTypeManager = $entity_type_manager; } /** * Determines course status based on dates. * * @param \Drupal\node\NodeInterface $node * Course node. * * @return array * Array with course status data. */ public function getCourseStatus(NodeInterface $node) { $status = [ 'state' => 'unknown', 'class' => 'course--unknown', ]; if ($node->hasField('field_start_date') && $node->hasField('field_end_date')) { $now = new DrupalDateTime('now'); if (!$node->field_start_date->isEmpty()) { $start = $node->field_start_date->date; if (!$node->field_end_date->isEmpty()) { $end = $node->field_end_date->date; if ($now < $start) { $status = [ 'state' => 'upcoming', 'class' => 'course--upcoming', ]; } elseif ($now > $end) { $status = [ 'state' => 'completed', 'class' => 'course--completed', ]; } else { $status = [ 'state' => 'active', 'class' => 'course--active', ]; } } } } return $status; } /** * Gets related courses. * * @param \Drupal\node\NodeInterface $node * Course node. * @param int $limit * Maximum number of courses. * * @return array * Array of related courses. */ public function getRelatedCourses(NodeInterface $node, $limit = 3) { $related_courses = []; if ($node->hasField('field_course_category') && !$node->field_course_category->isEmpty()) { $term_id = $node->field_course_category->target_id; $query = $this->entityTypeManager->getStorage('node')->getQuery() ->condition('type', 'course') ->condition('status', 1) ->condition('field_course_category', $term_id) ->condition('nid', $node->id(), '!=') ->range(0, $limit) ->sort('created', 'DESC'); $nids = $query->execute(); if (!empty($nids)) { $related_nodes = $this->entityTypeManager->getStorage('node')->loadMultiple($nids); foreach ($related_nodes as $related_node) { $related_courses[] = [ 'title' => $related_node->label(), 'link' => $related_node->toUrl()->toString(), 'status' => $this->getCourseStatus($related_node), ]; } } } return $related_courses; } } 

{# node--course--full.html.twig #} {% set status = course_service.getCourseStatus(node) %} <article{{ attributes.addClass('course', status.class) }}> <header> <h1{{ title_attributes }}>{{ label }}</h1> {% if content.field_image %} <div class="course__image"> {{ content.field_image }} </div> {% endif %} <div class="course__status-badge"> {{ status.state|capitalize }} </div> </header> <div class="course__content"> {% if content.field_description %} <div class="course__description"> {{ content.field_description }} </div> {% endif %} {% if content.field_lessons %} <div class="course__lessons"> <h2>{{ 'Lessons'|t }}</h2> {{ content.field_lessons }} </div> {% endif %} </div> {% if related_courses %} <div class="course__related"> <h2>{{ 'Related courses'|t }}</h2> <div class="course__related-list"> {% for course in related_courses %} <a href="{{ course.link }}" class="course-card {{ course.status.class }}"> <h3>{{ course.title }}</h3> <span class="course-status">{{ course.status.state|capitalize }}</span> </a> {% endfor %} </div> </div> {% endif %} </article>