Add table footer support

Thanks for this issue! This is definitely blocked on https://github.com/ckeditor/ckeditor5/issues/12952.

+1 I am running into this issue as well. In my case, my table is driving a JS chart, and adding the contents of tfoot into tbody is causing the JS to fail.

Needing a fix for this.

I've created a new module called please_replace_ckeditor5_with_tinymce

added a text filter plugin in src/Plugin/Filter/TableTfootFixFilter.php

namespace Drupal\please_replace_ckeditor5_with_tinymce\Plugin\Filter;

use Drupal\filter\FilterProcessResult;
use Drupal\filter\Plugin\FilterBase;

/**
 * Wraps orphan <tr> tags after </tbody> in a <tfoot> section.
 *
 * @Filter(
 *   id = "table_tfoot_fix_filter",
 *   title = @Translation("Fix orphan 'tr' after 'tbody' by wrapping in 'tfoot'"),
 *   description = @Translation("Wraps 'tr' elements that appear after 'tbody' with a 'tfoot' block."),
 *   type = Drupal\filter\Plugin\FilterInterface::TYPE_TRANSFORM_IRREVERSIBLE,
 *   weight = 101,
 *   provider = "please_replace_ckeditor5_with_tinymce",
 *   settings = {}
 * )
 */
class TableTfootFixFilter extends FilterBase {

  /**
   * {@inheritdoc}
   */
  public function process($text, $langcode) {

    // Match closing </tbody> followed by one or more <tr> elements not already wrapped.
    $pattern = '#</tbody>\s*((?:<tr\b.*?</tr>\s*)+)(?!\s*</tfoot>)#is';

    $text = preg_replace_callback($pattern, function ($matches) {
      return '</tbody><tfoot>' . $matches[1] . '</tfoot>';
    }, $text);

    // Process each <table> individually.
    return new FilterProcessResult(
      preg_replace_callback('#<table\b[^>]*>.*?</table>#is', function ($table_match) {
        $table = $table_match[0];

        // Match all <tbody> blocks inside the table.
        preg_match_all('#<tbody\b[^>]*>.*?</tbody>#is', $table, $matches);

        if (count($matches[0]) > 1) {
          $last = array_pop($matches[0]);

          // Replace last <tbody> with <tfoot>.
          $last_tfoot = preg_replace([
            '#^<tbody([^>]*)>#i',
            '#</tbody>$#i'
          ], [
            '<tfoot$1>',
            '</tfoot>'
          ], $last);

          // Replace the last occurrence in the table with <tfoot>.
          $pos = strrpos($table, $last);
          if ($pos !== false) {
            $table = substr_replace($table, $last_tfoot, $pos, strlen($last));
          }
        }

        return $table;
      }, $text)
    );
  }

}

Enable this filter on all text formats using ckeditor5.

We also have a other text filter plugins in the please_replace_ckeditor5_with_tinymce module called VideoCleanupFilter.php and SpanLinkFixFilter.php . Perhaps we will have to turn the please_replace_ckeditor5_with_tinymce module into a full contrib project so that others can get our text filter plugins that put a bandaid on content that would otherwise be broken by ckeditor5.

Please click the thumbs up on this pull request that fixes the issue at the root which is in ckeditor it'self.

https://github.com/ckeditor/ckeditor5/pull/14276

Governance issues.
https://github.com/ckeditor/ckeditor5/pull/14276#issuecomment-2815624337