ACF – Bypassing restrictions to allow HTML rendering in Gutenberg Blocks on the frontend.

yolo.php

<?php

// Context : emergency project where there are hundreds of broken pages; not sure why, I came to fix it
// This is just one small part, yet the most hackish, I've had to do, because Gutenberg scripts the entire $attributes
// On the block before it reached the `acf_render_block_callback`

add_filter( 'block_parser_class', function() {
  return 'X_WP_Block_Parser';
});

add_action( 'wp_head', function() {
  if( is_admin() )
    return;

  $all_registered_blocks = WP_Block_Type_Registry::get_instance()->get_all_registered();

  foreach( $all_registered_blocks as $registered_block ) {
    if(!str_starts_with($registered_block->name, 'acf/'))
      continue;

    $registered_block->render_callback = 'x_hijack_acf_render_block_callback';
  }
} );

function x_hijack_acf_render_block_callback( $attributes, $content = '', $wp_block = null ) {
  $current_position_from_parse = X_ACF_Raw_Data::read_current_position();

  if(empty($attributes['name']) && !empty($current_position_from_parse)) {
    $attributes = $current_position_from_parse;
  }

  return acf_render_block_callback( $attributes, $content, $wp_block );
}

class X_WP_Block_Parser extends WP_Block_Parser {

  public function parse($document) {
    if (!str_contains($document, 'wp:acf/')) {
      return parent::parse($document);
    }

    $pattern = '/<!--\s*wp:acf\/[a-zA-Z0-9_-]+\s*({.*?})\s*\/-->/s';

    // Perform the regex match
    preg_match_all($pattern, $document, $matches, PREG_SET_ORDER);

    if (empty($matches)) {
      return parent::parse($document);
    }

    foreach( $matches as $match ) {
      $raw_json = $match[1];
      $data = json_decode( trim( $raw_json ), true );

      if (json_last_error() !== JSON_ERROR_NONE) {
        X_ACF_Raw_Data::add( null );

        continue;
      }

      X_ACF_Raw_Data::add( $data );
    }

    // Return the parsed document after replacements
    return parent::parse($document);
  }

}

class X_ACF_Raw_Data {

  public static $by_position_data = [];
  public static $_read_data_position = 0;

  public static function add( $data ) {
    self::$by_position_data[] = $data;
  }

  public static function read_current_position() {
    if(isset(self::$by_position_data[self::$_read_data_position])) {
      return self::$by_position_data[self::$_read_data_position++];
    }

    self::$by_position_data[self::$_read_data_position] = 0;

    return self::$by_position_data[self::$_read_data_position++];
  }

}