CKEditor Templates Upgrade

This module provides an upgrade path for ckeditor templates created using the
https://www.drupal.org/project/ckeditor_templates_ui module into the CKEditor 5
ready version of https://www.drupal.org/project/ckeditor_templates.

Warning: Never use this module without testing and creating a database backup in production, it will change existing content!

Make sure to read through the README before installing the module. In most cases, you will want to customize which templates are migrated and/or wrapped via the events dispatched by the module before installing it and processing content via cron.

Features

This module does the following two things upon installation:

1. Migrates existing templates created via ckeditor_templates_ui module into the
   new entity type available in ckeditor_templates ckeditor5 version.
2. Updates all existing content to wrap existing template embeds with wrapping
   markup that gets added around the template when embedding a template in
   ckeditor5, namely

<section class="ckeditor-template-wrapper"><div class="ckeditor-template-content"></div></section>

Why update existing content?

When upgrading a site with existing template embeds to ckeditor5, these existing embeds are not recognized by the ckeditor_templates module as templates when upcasting the markup into Ckeditor5's DOM.

That means they won't be wrapped with a ckeditor widget frame as new template embeds will. In some situation, this causes major difficulties when attempting to amend existing content. Imagine for example a column layout with multiple rows based on templates and an editor wanting to add new rows in the middle of existing rows. Without the ckeditor widget's ability to insert newlines, this becomes really cumbersome.