Navigating Entity Reference Field Consolidation in Drupal Migration

During a recent Drupal-to-Drupal Migration Workshop, Joe Shindelar, Lead Developer and Lead Trainer at Drupalize.me addressed a participant's inquiry on merging two entity reference fields into a single field during the migration process. This particular challenge involves transitioning from a Drupal 7 event content type with separate entity reference fields for sessions and sponsors to a streamlined Drupal 10 setup with a unified entity reference field encompassing both sessions and sponsors.

Shindelar proposed a practical solution that leverages the merge plugin from the Migrate Plus module to integrate values from 'field_related_sessions' and 'field_related_sponsors' into a consolidated 'field_merged.'

As outlined by Shindelar, the migration process sheds light on the complexities of handling potential duplicate values within the source data. The article explores various approaches to overcome this challenge, including using the merge plugin alongside array_build and sub_process for meticulous de-duplication. This involves creating a new array, '_field_related_content_deduped,' and employing the callback plugin to leverage PHP's array_chunk() function.

Additionally, the article introduces the possibility of a custom process plugin as an alternative solution for tailored handling of duplicate values during the migration process.

While acknowledging that the presented solution may not be the most elegant, the article encourages collaboration and invites readers to share insights for refining and enhancing the migration process.

Learn more with "Merge the Values of Two Entity Reference Fields During a Drupal 7 to Drupal 10 Migration."