Polylang / Enfold incompatibility inserts custom_class=

thank you, I have sent details below in private content.

Thank you Ismael. How strange it was on an older version as I use the Theme update function. I have manually re-uploaded to the latest version and the same problem exists.

Thank you Ismael for looking into this. It is certainly a mystery as to why this custom_class is being added.
I have checked your changes and unfortunately when moving this function to live (and flushing the cache) the issue remains and the pages appear broken. So I don’t think this is filtering. The page you prepared was down to manually removing the custom_class in every page element.
Can you suggest any further ways we can look into this, as obviously having to go through every page element to remove custom_class in the ID is not practical going forward. Any thoughts you have are appreciated…?

Many thanks

Thanks Ismael,

You said that you manually cleaned up the code, so when I added it to the live site, I was seeing the same issues as before.

I am now just testing the following, which appears to be working, but did break the nav builder when I first ran it, so filtered this so it would only work on pages and posts.

I will update as to if it works fully.

Thanks

/**
 * ============================================================================
 * POLYLANG + ENFOLD CUSTOM_CLASS ISSUE FIXES
 * ============================================================================
 * 
 * Problem: When Polylang duplicates/translates pages, it incorrectly converts
 * custom_class attributes into id="custom_class" or id="custom_class=" in HTML output.
 * 
 * Solution: Multiple filters at different points in the translation/save process
 * to catch and fix the issue wherever it occurs.
 */

/**
 * Solution 1: Fix content after Polylang processes it (Primary Fix)
 * This runs after Polylang has translated the content but before it's saved
 * 
 * CRITICAL FIX: Handles unclosed custom_class=' attributes that break Enfold's parser
 * IMPORTANT: Excludes nav_menu_item to prevent menu structure issues
 */
add_filter('pll_filter_translated_post', 'fix_polylang_custom_class_issue', 20, 4);
function fix_polylang_custom_class_issue($tr_post, $source_post, $target_language, $data) {
    if (!$tr_post instanceof WP_Post) {
        return $tr_post;
    }
    
    // Exclude menu items - they don't contain Enfold shortcodes
    if ($tr_post->post_type === 'nav_menu_item') {
        return $tr_post;
    }
    
    $content = $tr_post->post_content;
    $original_content = $content;
    
    // Fix 1: Remove malformed id="custom_class=" or id="custom_class" in HTML
    $content = preg_replace(
        '/\s+id=["\']custom_class(?:=["\'])?/i',
        '',
        $content
    );
    
    // Fix 2: Fix unclosed custom_class=' attributes (THE MAIN ISSUE)
    // Pattern: custom_class=' followed by space, closing bracket, or end of shortcode
    // Replace with custom_class='' (properly closed empty attribute)
    $before_fix2 = $content;
    $content = preg_replace(
        "/custom_class='(?=\s|'|])/i",
        "custom_class=''",
        $content
    );
    $fix2_count = substr_count($before_fix2, "custom_class='") - substr_count($content, "custom_class='");
    
    // Fix 3: Also handle custom_class=" (double quotes, unclosed)
    $before_fix3 = $content;
    $content = preg_replace(
        '/custom_class="(?=\s|"|])/i',
        'custom_class=""',
        $content
    );
    $fix3_count = substr_count($before_fix3, 'custom_class="') - substr_count($content, 'custom_class="');
    
    // Fix 4: Remove custom_class='' or custom_class="" if they appear as standalone (no value)
    // This cleans up empty attributes that might cause issues
    $before_fix4 = $content;
    $content = preg_replace(
        "/\s+custom_class=['\"]{2}/i",
        '',
        $content
    );
    $fix4_count = (substr_count($before_fix4, "custom_class=''") + substr_count($before_fix4, 'custom_class=""')) - 
                  (substr_count($content, "custom_class=''") + substr_count($content, 'custom_class=""'));
    
    // Fix 5: Fix in shortcode attributes - sometimes custom_class becomes id in shortcodes
    $before_fix5 = $content;
    $content = preg_replace(
        '/\[([a-z_]+)([^\]]*?)\s+id=["\']custom_class(?:=["\'])?([^\]]*?)\]/i',
        '[$1$2$3]',
        $content
    );
    $fix5_count = substr_count($before_fix5, 'id="custom_class') - substr_count($content, 'id="custom_class');
    
    // Debug logging (only if WP_DEBUG is enabled)
    if (defined('WP_DEBUG') && WP_DEBUG && $content !== $original_content) {
        error_log(sprintf(
            '[POLYLANG FIX] Post ID %d: Fixed %d unclosed custom_class=\' attributes, %d unclosed custom_class=", %d empty custom_class, %d id="custom_class" issues',
            $tr_post->ID,
            $fix2_count,
            $fix3_count,
            $fix4_count,
            $fix5_count
        ));
    }
    
    $tr_post->post_content = $content;
    return $tr_post;
}

/**
 * Solution 2: Clean content when post is saved (Backup Fix)
 * This catches the issue at save time as a safety net
 * 
 * CRITICAL: Fixes unclosed custom_class=' attributes
 * IMPORTANT: Excludes nav_menu_item to prevent menu structure issues
 */
add_filter('wp_insert_post_data', 'clean_custom_class_on_save', 10, 2);
function clean_custom_class_on_save($data, $postarr) {
    // Exclude menu items - they don't contain Enfold shortcodes and menu structure is in postmeta
    if (!isset($data['post_type']) || $data['post_type'] === 'nav_menu_item') {
        return $data;
    }
    
    if (!isset($data['post_content'])) {
        return $data;
    }
    
    $content = $data['post_content'];
    
    // Fix 1: Remove id="custom_class=" or id="custom_class" from content
    $content = preg_replace(
        '/\s+id=["\']custom_class(?:=["\'])?/i',
        '',
        $content
    );
    
    // Fix 2: Fix unclosed custom_class=' attributes
    $content = preg_replace(
        "/custom_class='(?=\s|'|])/i",
        "custom_class=''",
        $content
    );
    
    // Fix 3: Fix unclosed custom_class=" (double quotes)
    $content = preg_replace(
        '/custom_class="(?=\s|"|])/i',
        'custom_class=""',
        $content
    );
    
    // Fix 4: Remove empty custom_class='' or custom_class="" attributes
    $content = preg_replace(
        "/\s+custom_class=['\"]{2}/i",
        '',
        $content
    );
    
    $data['post_content'] = $content;
    return $data;
}

/**
 * Solution 3: Clean content right after Polylang duplication
 * This runs immediately after Polylang creates a sync post
 * 
 * CRITICAL: Fixes unclosed custom_class=' attributes that break Enfold
 * IMPORTANT: Excludes nav_menu_item to prevent menu structure issues
 */
add_action('pll_created_sync_post', 'clean_enfold_content_after_duplication', 5, 4);
function clean_enfold_content_after_duplication($post_id, $tr_id, $lang, $strategy) {
    $post = get_post($tr_id);
    if (!$post) {
        return;
    }
    
    // Exclude menu items - they don't contain Enfold shortcodes
    if ($post->post_type === 'nav_menu_item') {
        return;
    }
    
    $content = $post->post_content;
    $original = $content;
    
    // Fix 1: Remove malformed id="custom_class" issues
    $content = preg_replace('/\s+id=["\']custom_class(?:=["\'])?/i', '', $content);
    
    // Fix 2: Fix unclosed custom_class=' attributes (THE MAIN ISSUE)
    // Replace custom_class=' (unclosed) with custom_class='' (properly closed)
    $before_fix2 = $content;
    $content = preg_replace(
        "/custom_class='(?=\s|'|])/i",
        "custom_class=''",
        $content
    );
    $fix2_count = substr_count($before_fix2, "custom_class='") - substr_count($content, "custom_class='");
    
    // Fix 3: Fix unclosed custom_class=" (double quotes)
    $before_fix3 = $content;
    $content = preg_replace(
        '/custom_class="(?=\s|"|])/i',
        'custom_class=""',
        $content
    );
    $fix3_count = substr_count($before_fix3, 'custom_class="') - substr_count($content, 'custom_class="');
    
    // Fix 4: Remove empty custom_class='' or custom_class="" attributes entirely
    // Enfold doesn't need empty custom_class attributes
    $before_fix4 = $content;
    $content = preg_replace(
        "/\s+custom_class=['\"]{2}/i",
        '',
        $content
    );
    $fix4_count = (substr_count($before_fix4, "custom_class=''") + substr_count($before_fix4, 'custom_class=""')) - 
                  (substr_count($content, "custom_class=''") + substr_count($content, 'custom_class=""'));
    
    // Fix 5: Ensure custom_class attributes with values are properly formatted
    $content = preg_replace_callback(
        '/\[([a-z_]+)([^\]]*?)\s+custom_class=([^\s"\']+)([^\]]*?)\]/i',
        function($matches) {
            // Ensure custom_class has quotes if missing
            $value = trim($matches[3]);
            if (!preg_match('/^["\'].*["\']$/', $value)) {
                $value = '"' . esc_attr($value) . '"';
            }
            return '[' . $matches[1] . $matches[2] . ' custom_class=' . $value . $matches[4] . ']';
        },
        $content
    );
    
    // Debug logging (only if WP_DEBUG is enabled)
    if (defined('WP_DEBUG') && WP_DEBUG && $content !== $original) {
        error_log(sprintf(
            '[POLYLANG FIX] Post ID %d (from %d): Fixed %d unclosed custom_class=\', %d unclosed custom_class=", %d empty custom_class attributes',
            $tr_id,
            $post_id,
            $fix2_count,
            $fix3_count,
            $fix4_count
        ));
    }
    
    if ($content !== $original) {
        wp_update_post(array(
            'ID' => $tr_id,
            'post_content' => $content
        ));
    }
}

/**
 * Solution 4: Clean content on frontend display (Final Safety Net)
 * This ensures broken content doesn't display even if it got into the database
 */
add_filter('the_content', 'remove_custom_class_id_from_html', 999);
function remove_custom_class_id_from_html($content) {
    // Remove id="custom_class=" (malformed with extra equals)
    $content = preg_replace('/\s+id=["\']custom_class=["\']?/i', ' ', $content);
    
    // Remove id="custom_class" (literal value only)
    $content = preg_replace('/\s+id=["\']custom_class["\']/i', ' ', $content);
    
    return $content;
}